Part 40 - cd3wd440.zip - Offline - Small Scale Recycling of Plastics

Part 40 - cd3wd440.zip - Offline - Small Scale Recycling of Plastics
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REFERENCE
LIBRARY
A project ?f Volunteeis
in Asia
Small
of -Plastics
Scale
Recycling
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Intermediate
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Avai 1able Tram:
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Publications
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9 ‘King Street
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London WC2E 8HN
ENGLAND
Reproduced
by permiss ion.
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SMALL SCALE RECYCLING OF PLASTICS
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BY
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JON VOGLER
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TECHNOiOGY PUBLICATIONS 1984.
IliThMEDIATE
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Acknowledgement
The author wishes to express his 'gratitude
to the
Overseas Development
Administration
Iof Her Majesty's
Government for fi-naneial
support
for the preparation
of'this
book but to stress
tha't the views expressed
are entirely
his own and do not necessarily
repr.esent
the views of O.D.A.
*
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Intermediate
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Printed
Technology
fiblications,
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London.
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n CONTENTS
CHAPTER
*
9
u
4
1.
Why recycle,piastics?........;.............ti.l
.’
l
.
‘The plastics
industry
- its processes,.,
[email protected] and structur%............'....".....
2.
*
4
N
-.
_
y-.---Giving
the customer
4.
Collection&f
5.
Processing
what he wants...........18
plasti~cs
,
waste.....l.:.....:*..yl
. . . . . . . . . . . . . . . . . . . . . . . . . . ..k.....
+.
Manufacture
and sale oftismall
articles
r‘
from reclaim . . . . . . ..I.......................
6.
0
79
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67
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APPENDICES
7
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Ik'f(
.
About,plastics"
- their
chemistry
and
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
structure
.
index. . . . . . . . . . . . . ". . . . . . . . 88
,
Manufacturers
of plastics
recycling
.a -'equipment .a.......................ti..........
90
'%
II.
*
'
' ' Test
III.
l
for
melt
flow
*
‘t
1 L
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. BIBLIOGRAPHY . . . . . . . . c ..,....:
%
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LIST OF ILLUSTRATIONS
COVER P,ICTBRE:
'& Plastics
Recycling
Projectestablished
a
4%
TITLE
.-FIG..
1
._ 2
3
4
5
6
7
8
9
10
11
12
13
14
'-15
16 ,-"
17
18
19
20
21 v
22
23 '*
24
25
26
27
in Kenya.
by the Author
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PAGE'
.
t
...5
.
The principles
of Injection.moulding
...........
...5
The principles
of Extrusion
....................
The principles
of Blow '?noulding............... ...6
..c ..............
.............
Blown film extrusion
7.
..i .............
13
Objects made of LDPE ..............
..s..., ..... 13
.
. Objects made of HDPE...................
*,.. 14
' Objects made of PP .............................
:A ..
..?-a
:. .......
14.
Objects'made
of PVC..................
15
Objects made of PS ...............................
15
Objects made of ABS.. ..p ..........................
Objects made from mixed plastics
was>te...........2
9
............................
40
Washing scrap plastic
............................
40 .
Testing by floatat,ion
"42
ej.
Testing
by burning ...............................
Cutting
scrap on a circular
saw.;.................4
2
. ...........
-(horizontal
axis) ......
Granulator
0
axis) ;.........;........5
Granulator
- (horizontal
axis)................,......5
1
Granulator
- (ver,ti,cal
Homg-made Granulator
(vertical
axis).............5
4 '
Bags of flake from granulated
film....;.......;...5
4
The Foliolux.Crumber.......;.................~...5
6 .
..5
7
Crumb - a hard, beady material .................
"{
..c ..... 58
....................
- pelletizer
' Extruder
60
............................
Extrud,er - -pelletizer
68
Small injection
moulder ..........................
73
Small mouldable
objects ..........................
9
Rig for measuring
melt flow index...............;8
5
..4
.
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CHAPTER 1:
WHY RECYCLE PLASTICS?
,j!
*
The subject
of this book is how to create empBbyment by recycling
Although
it
is primarily
intended
for
use in'
plastics.
developing
countries
the principles
are universal
and may equally
the, quantity
of
Indeed,
be applied
in industrialised
.na.tions.
suse is far higher
plastic
products
which are thrown away after
population
has a "consumer"
life
style,
so
where the whole
opportunities
may be greater
in such countries.
.,1 i
It describes
the collection.,ef
plastic's
waste that has been used
once-'in-the
world outside
and can be col1ecte.d
and processed for
return
to the factory
and remoulded for a second-service
life.
The book does not cover recycling,
by the plastics
industry,
of
much of what is
scrap
produced
within
the factory,
although
The techniques
and equipment
used
included
may be applicable.
and the skills
available
in the factory
situation
are more comj_
plex than the simple machines and procedures
covered here.
1
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In an' age when worldwide
unemployment
has reached
levels
not
previously
expected,
it is not necessary
to justify
any book that
introduces
employment creation
opportunities.
The opportunities
offered
by plastics
recycling
appear attractive
and have not been
.developed fully.
The reasons have been explained
in "Remoulding
They" are an. important
the, Future"
(Ref.1).
warning
of the
mistakes
and failures
of the past, but are too lengthy
to repeat'
here.
‘The reasons why recycling
offers
good job creation
prospects have been discussed
in "Work from Waste", (Ref. 14).
Some
further
reasons,
peculiar
to plastics,
must be presented
here, if
only to persuade the reader to continue.
They are as follows:1
/'
'
Some recycling
activities
are not pro'fitable:
they cost more than'
they earn.
'
In general'those
are most profitable
that deal in
high value materials.
' d
For example the recycling
of high grade
waste
paper,
such as computer
paper,
is usually
far more
profitable
and less problematl?c
than that of newspaper and card',I
board which have low value.
Pxastics,
which are mkinly
derived
; '
from petroleum,
are expensive
materials,
at least
in terms of.:
their
weight.
This means they &an be recycled
profitably;
but
caution!
.
?\
One reason why high value is important
js that
transport
costs,
normally
dominate
recycling
economics
- if
the value
is high
compared with the transport
cost then a profitable
operation
is
frequently
possible
and vice versa.
Transport
costs depend not
\
only upon weight but also on volume.
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It is no use having
a high value if the volume is so high that
even though the ratio
of value to
transport
costs are excessive,
This is,why
so much attention
will
weight may be advantageous.
.
be paid to volume ,reduction
throughout
this book. _,'
Recyclability
'
0
Some materials
are naturally
recyclable,
others
are no?.
of the same
example, scrap copper can be melted to produceYingots
Waste paper on ,the
quality
as ney copper,
smelted
from ore.
other hand can never be restored'
to its initial
quality
no matter
Plastics
are near
what care is taken in refining
and purifying.
the better
end of the recyclability
scale.
If they are properly
cleaned
and foreign
matter
is removed,
the quality
of some
plastics
can be almost as good on the second use as on the first.
Not always however.
PVC for example can suffer
seriouslyduring
the recycling
process
unless
care is taken.
For explanation
of
.
see
Table'1
(Page
IO).
"PVC" and other initials
m
.'
b
'
Labour intensity
,
, 4
5
.
The recycling
process
can be broken down into different
stages,
The initial
stages:
cblleotion,
some of which are optional.
labour
intensive
and
sorting
and cleaning
of material
are all
require
little
capital
equipment.
The work .is suitable
for those
who have little
skill
and the sorting
"and ‘cleaning'may
be done by-"
people with certain
sorts of disability.
.
Investment
progression
FThe later
&ages do require
investment
in equipment,.which
may be
bought using the profits
of the earlier
stages if outside
fina,nce
is not available.
This
pyevents
complex
developments
before
early
stages
have .been learned
and consolidated.
L For those
lacking
previous
industrial
experience,
this may be es‘sential
to
ultimate
-success.
However this
is a slow process
and) to have
capital
ready from the start
may be more-attractive
to those who
are 5mpatient
or Lambitiou&
although
it 'does increase
the risk
.
6'
a
and &zale of failure.
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benefit
I
2
Bee&se
it degrades
slowly
under‘the
effecfs“of
wind,
sun and B
'rain,
plastics
waste is one of'the
most objectionable
kinds of
; litter..
It lies
around streets
and open spaces 'for
weeks or
monthsrafter
it has been dropped.
“It
'may .bec&e
coated with
,
other,
objectionable
wastes,
provide
a harbour
for vermin
and
insects
and block up drainage
systems.
Any process of recycling
-+ ,
that
places
a
value
upon
this
material,
so
that' there is a finan-‘
'd
‘
cial
advantage in preserving
it rather
t$an discarding
it,
is to
. ,D
be
welcomed.
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is greater
in poor urbaneareas,'
where even small
The
will
be seized,
as these are the, districts
earning
opportunities
east thorough.
where municipal
cleansing
is frequentForeign
exchange
improvements
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Although
the manufacturing
of plastics
products
may be well
developed,
few developing
countries
make their
own raw materials.
If the products
are not exported
These are therefore
impo'rted.
Ry
recycling
local
.scrap,
these imports
r foreign
debt is created.
Where
plastics
feedstock
is"
and hence the debt, can be reduced.
produced
locally
recycling
may still
save energy
and raw
petroleum.
Low cost
I
raw materials
With good quality,
low cost,
secondary
material,
plastics
goods
manufacturers
can cheapen certain
kinds of products,
without
loss
Even a small margin may be the difference
of functional
quality.
competit"lve
price or loss leader,
or may
between profit
or ~Qss,
enable plastics
to be chosen in preference
to metalor
glass.
a
A chance for the urban poor
_
Finally,
a vigorous
plastics
recycling
industry
can hrovide
to earn a small income by
unique QR'portunities
,for the'poorest
collecting
waste materials
for sale to a recycling
plant.
No
may be passed from one to another with
capital
is needed, skills
little
difficulty,
so this
can provide
a catchnet
against
the
consequences
of extreme poverty.
.
This chapter
has mentioned
benefits
for the community,
for the
nation,
for industry
and5 for the" individual.
Involvement
of's0
many may be one reason why few initiatives
in plastics
recycling
are taken. Another
reason is the mystery
of the subject
and, toremove this,
Appendix I considers
what plastics
are, why they are
Readers
used as .they are and how products
are made 'from them.
may prefer
to study
Appendix
I before
embarking
on the next
i
Chapter..
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CHAPTER 3:
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THF: PIAS'kX
TNDUSTRY.
PROCKSES, PRODUCTS.AND STRUCTJJRR.
Manufacturing
I
F-
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Processes
;
I
Although
the recycler
may never
perform
any plastics
manuto know the-processes
used by the industry
facturing
operation,
The industry
is the recycler's
principal
market
is essential.
and only by understanding
the uses of 'the material
he produces,
will
marketable
quality
and best prices 'be obtained:
A company
that advertises
"Manufacture
*of all
types of' plastics
products"
%: +
may actually
perform mainly' operations
that cannot use recycled
For example food and drink
containers?are
produced by
material.
heat forming
thin pblystyrene
or ABS sheet.
This process cannot
use- raw material
in any other
form and although
reclaim'can
be
used to manufacture
the sheet,
its
use for food packaging
is
ruled out or-i health
grounds.
The following
descriptions
which
provide
indicate
polymer.
of the main manufacturing
markets
to the producer
of
operations
recycled
,
Large volume processes
0
'The four types of operation
that follow
use a greater'volume
of
polymer
than all
other
industrial
processes
andi all
can use
recycled
material
(or "reclaim")
if i$ ,is clean and pure. 'These
descriptions
are brief
but pro_cesses that can be performed by the
recycler
will
be described
in greater
detail'in
Chapter 6.
:'
Injection
moulding
(Fig.
.
I)
,
'
~
1)
~f
.
9
Injection
moulding
and extrusion
(below)
.are the processes
that
use the most raw material.
Pellets
or powder, are loaded into a
hopper which feeds it (by gsairity)
into the cylindrical
barrel
of
the moulding
machine.
It'is
forced' down the barrel
by rotation
of the spiral
screw
and becomes
heated
and "plasticized"
'
(softened)
in the process.
The temperature.
is controlled
by
electrical
heaters
or water (or air)
coolers
round the barrel.and
it is forced,
under high pressure,
'through .a specially
shaped
nozzle into a strong,
split,
steel mould.
The mould is kept cool
so that
the object
quickly
solidifies,
the *mould opens,
the
object
is removed and the mould closes for the next shqt.
Ther"e;
_
*
are“also
machines that use pistons
or plungers
instead
of screws.
The process is similar
to the pressure
die casting .of'non-ferrous
=
metals,
from which it was developed.
l
Extrusion
(Fig.
. This
is similar
no'zzle discharges
Q
$
.:
i
.
..
except
that
there
is no; mould.
Instead
the
"through
a die:
a steel
plate
pierced
w<th a
-4-
';
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1
Heating
elements
and
cooling
coils
c
Clamp
holds
mould
shu$
I
I
L-lSpiral
CJ
I
cz
cl
0
/
screw
FIGURE! t:
The principles
of Injec$ion
,I
moulding..
0
I
..
’
:
Mandr.el
aI front
supported
end
Die
/
.
Tubular
expands
leaves
product
as it
die
I
Spiral
screw of
val;iabl%
diameter
'
I
*
FIGURE 2:
The principles
.
of Extrusion.
.s
.,
>
s;
.
I.
7
-
.
..*
* /--=A
.e..
parallel
hole
which
determines
the" &a
of the,,continuous,
The extruded
material
.is
stream of plastic
that emerges ,' om it.
c
cooled and solidified
in air or a water bath or on a chilled
being
wound onto a reel
or' cut
into
straight;
drum, before'
Pressure
in the cylinder
bengths.
is applied
by one or more
like the extrusion
of
The'process,
continuously
rotating
screws.
originated
ifrom the manufacture
of spaghetti!,'
metals,
Blow moulding
(Fig.i.7)
,
_
R
' .
Bottles
and other hollow-objects
with a neck narrower
than their
body cannot be injection
moulded without
costly
complications
in
Blow-+&ding
is used instead.
It
the design
of the mould.
takes place in two stages similar
to the blowing
of glass.
First
a parallel
walled
tube,
called
a parison,
is extruded.
It is
then transferred
to a split
mould which has' been' shaped for the
final
object,
whose two halves
nip the end of the parison
to
close it.
Air is bl&wn into
the open end to expand it to the
shape of the mould.
The mould ,is kept cool and the finished
' article
solidifies
and is removed when the mould opens again.
The overall
thickness
of the article.may
be varied.,
'D
I
i' .''b --*
F
.
Mould
-+*.+ ‘: stage
-b
clqses
at second
to mi
‘en_d ofMRS
I
shut
P
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%
“? ’
Hollow
inner
I
:
mandrel
%
forms
of bottle
surface
l”\
Extruder
.a
and,
”
die
as
.
above
..
The principles
9
film
i
*
FIGURF: 3:
'_ _
--
,
Blown
mould
extrusion
(Fig.
4)
.
of Blow mou1din.g.
.
.
'"
."
L
',
This is a form of blow moulding
but the parison
is continuouslay
extruded
from a ring-shaped
die,
u,sually
vereically
upwards.
Air is. blown through
the centre of the'die
to expand it to a tube
of thin film.,
As the tube rises
it is cooled and .e+lidifies
and
at the top is folded
over and,flattened
between chilled
rollers,
thus preventing
air
from'escaping
out .of the. "bubble".'
After
t,
-
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:+
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3
41
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3
further
cool'ing
the 'collaps&d
tube is wound onto reels.
produce sacks or bags, the coils are fed through a machine
seals
the bottoms
and chops them off
in one operation.
produce flat sheet the tube is slit
down one side.
To
which
To
i .
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.
p
.s
I
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FIG&
4:
Bl?own film
.
extrusion.
9
i
4.
Less com.Son processes
The plastics
industry
operations,
in which
the raw material.
Callendering
c
also employs the following
less
common
a percentage
of reclaim
can be m$;tced with
'I
Jf
-:.
.-
This is another
way of producing
wide she.ets: .,-A- hot dough is
made from the raw materialWin
a heated mixing machine.
The dough
is squeezed through successive
heated rollers
to fo.rm a sheet of
the desired
thickness;
then through cooled rollers-and
reeled UP.
a
6
i
.
Special
grades of PVC can be* mixed cold with liquid
plasticis&
.This is formed into articles
by pouring
into a
.to form a paste.
split
mould which is rotated
so that the paste covers the inside,
.it is then heated.
ASter cooling
the rubbery solid
is peeled off
The process is slow but can use cheap
the inside
of the mould.
for
production
of small
number%' of
moulds ,and &, suitable
objects.
The paste can- also be used to coat cloth
(:'leathercloth")-or
to make washable wallpaper.
\
Slush
moulding'
*
'
Rotational
mouTding
_
.
.
quantities
by using
a .
Large hollow
objects
‘are made in small
low-cost,
low-strength
mould, into which a predetermined
quantity
'
of thermoplastics
in powder form is fed, followed
by rotation
(in
two directions)
in an oven.
The powdee plasticizes
and covers
the surface
of the mould evenly.
Rotation
continues,
during
1 cooling.
.
&$‘z
.
.,r
I
Coating,
s
.1
Plastics
may be. applied
to the outside
of other ‘materials,
.particularly
paper,
textiles
and metals,
to protect
them from
moisture
or chemical
attack.
Coating
can be done by roller,
by
spraying 'or by dipping.
Special
forms of materials
are available
for these processes.
Porous materials
may be impregnated
with
ar
0
plastics
in similar
ways.
. ,
IM WITHOUT PRIOR
THERMOPLASTIC PROCESSES THAT DO NOT USE
J
PROCESSING
.
0
I
1
Film
Casting
'used* to produce very acc&t~,.'high,quality
films,
for example
those used for photography.
, The material
is continuously
cast'
onto,a
smooth, flat,
moving beltOtto
form a .continuous
layer
of
perfect
smoothnesd and clarity
and unifo
Quality
is
more important
than cost and reclaim
*fro
outside
the plant
is
not used.
-
IS
a
”
.
.
0
./-
Thermoforming
d
d
Flat sheet is heated and formed, either:by
vacuum suction
into a
shaped mould or onto a shaped former or by squeezing
between male
,and female dies.
I-used
to .make cheap food and drink
cups
and trays
from
contipuous
coil
and large
parts,
such aa
refrigerator
lininge,
from..s,$ngle
sheets.?, Reclaim can be used* if
it is first
formed into.'&heets ,?# b& ONLY for'products
that do
'
come into contact'wi<h
food-.
) c
>I
.-. I' .
. '
L
,C
1
1
*
.*
?'
,L
\
%43-.
9
,,
not
”
.
.
3
\
I
!
3
?:
’
0
.
\
.
,
~~
__-.
__~
-....\
-
-_
c
;
f
L
P
4
l.
\
I
,
.
~
I
,-
*
.a
.
Fabrication
,
-_
/.
.
and other material
forms are cut, shaped
Sheets,
rods, extrusions
to make a wide
and- joined
by' screwing‘,
welding
or aaesives,
Fabrication
is mainly used when quantities
variety
of products.
are too small or the product
too complex to.justify
theYcost
of a
Qffcuts
can be recycled'into
small fabrications-:7
mould.
*
'_
Machining'..
ail
.\I
L’
t
.Plastics
are used in engineering
in the same way as
wood and *can be turned,
milled,
drilled
and planed
shapes.
The process
.is used where small numbers of'
are required.
Nylon is extensively
machined in the
cindustry.
i
Heat
sealing.
_
This
is used-to
convert
i
1
SCrinking
plastic
,
film
into
'
bags and packages.
r
Special
.film= are avai?lab,le
for "&rink
wrapping".
is loosely->:fsrapped
in' film
and heat. applied
to
controlled
temperature.
The film
shrinks
snugly
, .
object but is not melted.
Foam manufacture
J
metals .and
to required
parts
only
engineering
i
The article
a 'carefully
around
the
/_
'
-
:
'This is described
in Appendix 1.
There is no [email protected] 'reason
why reclaimed
polymer
should
not be used for foaming
but the
amount of polymer
used in foam production
is small
and most
producers 1 buy the material
ready
prepared.
Appendix!
III
includes
'the
name of one, of, many companies
that
recycle
pol‘gyurethane
foam into
foam groducts
and may be .willing.
to
licence
the process elsewhere.
v
/
"Thermoset
1' =
.
.
manufacturing
These will
be listed
to the recycle::
_Manuf&&ure
.e ,. .>.
moulding,
jet
Products
5-
i
operations
for
completeness-
,
but
are
'
1
1i
_
,L
*
of littlej:interest
1i,
of lamina,tss,
compressiou
moulding,
:transfer:
mouldingi
manufacture'
of reinforced
plastic
products.
of the Plastics
Industry.
2'
_
'
,
.
P
.
Table 1 and Figures.5.
most common polymers.
to 10 illustrate
the products
.
made from the
_\
?
P
.
.-
'
_.
.
.'
TABLE 1 COMMONRECYCLABLE PLASTICS
.
TYPICAL PRODUCTS -'
(Figs 5-10)
(Not'necessarilg
Recyclable.
Note that the
*same product may be made
from many materials).
c CHARACTERISTICS
POLYMER
:
,----------------;-----------,-,-----,,,--------------------------Low density
* Soft,
flexible
<polyethylene
Easy to heat seal.
Only -glass clear
if
(LDPE >
very thin;
thick
sections
are milky
white (or coloured).
r
3
g‘
I
I
.
Film bags, sacks 'and
sheeting.
blow-mouldedbot!t&&-1-m.
Food boxes
Flexible
piping
and hoses,
-household buckets,
bowls, . I
Cable coverings,
. etc.
usually
te3ephone cables.'
.
--------------------------------r----r----~------------------------~---Medium density
Intermediate
between
Squeetie bottles.
.')
,polyethylene
LDPE and HDPE.'
a
(mm)
------------------------------------------------------------------.G
High density
Tough, stiffer
than
'High strength
film for .
polyethylene
LD.Even thin film is
sacks and'bags.
Larger '
~ r
bottles,
buckets,
crates,
milky (or coloured).
(HDm)
..
jerry
cans, pallets,
dustbins
and other
household,objects.
'
.I
-----------------------r--------'------------------------------~PolypropyLike HDPE but harder
Chairs
and other furniture.
lene (PP)
and more rigid.
Can
Best quality
homewares .and
_
be bent-sharply
other strong mouldings,such
'
without
breakiw.
as car battery
housings,
other car and domestic
*
appliance
parts,
jerry
cans, wine barre,ls,
crates<,
.
pipes and fittings.
Rope, '
string,
-strapping,
tape and'
.woven sacking and carpet
*
,backings,
netting.
Heat
!.;riented..
hfib is
.:,,
sterilizable
surgical
1.."
-<
tough and very clear.
'.goods.
I
”
.
e
\
~
,
II
‘A,
---------------------------------------------------------~~---------~---
.’
1
I
‘\
a
Rigid
polyvinyl
chloride
('PVC>
Hard
I
and
rigid.
its unplasticiaed
form.
in
_. ..-_
.Wa$er-,and-
.~r~~~~~ion..p~pe~-.--,.,,
and fittings.
Gutters
and,,',
rainwater
pipes, window+, 1
building
panels.
L
“.
~_ ~~.
,
?.
,
TABLE 1 - cont.
TYPICAL PRODUCTS 5
CHARACTERISTICS
POLYMER
------------------------------------------------~------~---------------------Sports and toy balls,
Soft,
flexible,
Plasticized
inflatable
toys and boats.
rather
weak.Can
be
PVC
Toys,
dolls,
noveltiesi'
highly
transparent.
7
Hose, cable'coverings;'
Easily
bonded to
i*
Suitcases,
handbags,
other
textiles,
metals
etc.
,
luggage.
Shoes, .flooring,
raincoats,
shower curtains,
,
l
liquids,
,pallet
.
.
---------------------------------------------------------Polystyrene
.Easily
moulded,
but
brittle.
(PSI
Can be crystal
"
'c,lear .
I
\
clear
covers
--T--.e------.
radio
cases
,, --'we-----Impact
modified
,
PS
Less brittle'but
no longer clear.
/
8.
'Refrigerator
and other
mouldings.
take-away
heels.
--,---,,,,,-,-,-,-,,,,,,,,,,,-----,---------------------------------Expanded PS
Very lightweight,
expanded foam
white,
- not economic to
\
recycle.
---------------------------------------------~-----------~----------~~-Acrylonitrile,
Tough, stiff,
easiiy
Butadiene
moulded ‘to give
Styrene
shiny surface
finish.
' (ABS‘) "+
Good resistance
to
afood, oils etc,.
.
’
interiors
domestic appliance
Vending c'
food trays.
Ceiling
tiles,
insulation,
packings,
padding.
",,
5
_'
l'
Y
'.',.,
\..
Food (especially
margarine)
containers.
Teleppgne handsets & other off?36
equipment,
came% housings.
__ ~.-- ~~~
Domestic applianoe
parts.
Electrical
hand tools.,
rj '
Toys.
-------------------$--------------------------~-------------------------
Polyamides
(Nylons)
b Strong,
very tough,
machinable.
Slippery
low friction
~ Engineering
uses such as
gears, bearings.
Domestic appliance
parts,
pipe fittings.OTextYle
~ yarn,
fishing
-line*,
netting,
hose reinforcement'
brush bristles,.surgical
i tw-iae ta .~e.q~&-&gngs-.
_
1
,
.
1
The following
occur
e
.
.
TABLE 1 T cont.
.
POLYtiR
'
in lesser
.
,
quantities:&
,
' .
CHARACTERISTICS
'
TYPICAL PRODUCTS
‘\
I
.s
Polymethyl
Methacrylate
(Persper
or Acrylic)
;
4
-
Rigid, ~transparent,
Illuminated
display
signs.
' attractive
when
'
Glazing,
esp. of airoraft.
colou,red.
Excellent
Automobile;Light
and
residance
to
optical
lenses.
. .
weather.
Telephones,
furniture,
---.piano
keys.
+
e
""------------?----'--'-""-------------------~--------------~---------------Polygthylene
,Tough,
clear,nvery
Polyester
te%tile
yarn.'
Terephthalate
strong.
Exdellent
Magnetic
recording
tape.
'
(Polyester,
electrical
properties
Transparent
."oriented"
Terylene,
Can be shrunk for
film for packaging.
c
.
I . Soft drink bottles.
PET)
3
packaging.
Photographic
film base.,
.
Industrial
strapping.
-----------------------------------------------------------------------Polycarbonate
Very strong,
rigid,
Lenses for strong electric
I
heat resisting,
‘lighting,
Baby feed,
_
(PC>
.
tasteless,
bottles,
Tools, Glazing,
stai
resistant;
,Heat resistant
kitchen
/Landa2 resistant,
ware.
/can be crystal
clear.
.*
.
-------,-i,,,--_ ---""--'----'-----------r---l,,---,,,,-------------: !/ Flexible,
Polyurethane,
rubbery,
As foam for furniture
1
(PU)
i with good insulation
;
.
. fillings,
packaging,
\
/ properties.
insulation,
sponges.
As solid
for tyres,
shock
'
-..
.
n
> iI
mounts, roller
coverings,,
I
sees.
With textiles
.for<-,.,
I
I
.c E othing.
---,------_-____________________________---~"~---------l
.-
-------.
----
+L.---
I
i
.
/
.
j
j
i
*
I
q
FIGURE 5:
f Objects
FIGURE 6: 1 Objects
made of 'LDPE.
made of HDPE: '
\
,
/’ ’
_-’
/
.;
--I
a
l
\I 6
FIGURE 7:
Objects
made of PP.
\FIGURE 8:
Objects
made of PVC.. 'i
.
,
.
FIGURE 9:
Objects
m&de of PS.
FIGURI? 10:
Objects
made of ABS.
'
STRUCTUREOF THE PLASTICS INDUSTRY
l+
The would-be
recycler
the plastics
industry.
general but there will
, Raw Material
’
i’
also needs to understand
the structure
of
The- followings
pattern
is likely
to be
be some!ivariation
from country
to country.
' -1
Producers
These are (usually
large)
chemical
and petroleum
companies who
produce
"virgin"
plastic
feedstock,
(sometimes
called
resin
or
The main influence
they have on the
polymer)
in huge quantities%..,
availability
of virgin
materials.
recycler
is to fix price&.&d
that determine
the
It is these, not the co$$ of his operations,
price
a recgcler
can chnrge for "secondary"
material.
Qirgin
material
is delivered
in powder or pellet
form,
in plastic
or
paper sacks of around 20 kilos
weight,
in large cardboard
drums
that hold many times that quantity.or
ev'e"n by road tanker. .
.*
Compounder3
a.
.
These specialist
companies,
usually
small,.stock
various
polymer3
and provide
the manufacturers
of plastic
goods with
technical
advice
and the most suitable
materials
or mixtures
for
each
individual
need.
In addition
to basic polymer,
the compounder
stocks
plasticisers,
anti-oxidants,
stabilizers,
accelerators,
colouring,
and other additives.
The*compounder'is
often the best
market for the recycler
because he possesses
superior
technical
knowledge and has a large volume throughput
of virgin
material,
in which small percentages
of reclaim
will
reduce cost without
seriously
affecting
the quality
required‘by
the moulder.
,,
.
Stockists
These warehouse3
stock
polymers
and compounds
but neither
manufacture
themselves,.
Thky
nor provide
a compounding service.,
may be agents -or subsidiaries
$ f the produoer
'companies or de+
partments
of companies concerned,@th
the supply of other materials such as chemicals,
rubber or“paper.
They! may b," willing
to
stock reclaim
alongside
virgin
materials,
especially
if
these
are
,
' ..*'4
in short supply.
$ ,
Moulders,
-. 1 f. 1
These buy 'their
raw materials
from compounders.
If they do their
own compo-ding,
or,if
the material
is used as produced and does
not need comWpounding,r they may buy direct
from stockists
or
producers.
The term "moulder"
is used generally
to cover those
that extrude,
callender,
cast or thermoform
as well as injec&on'
moulders.
They are specialists
in plastics
and do not 'perform
other types ,of manufacturing.
'
Specialist
*
I’
Y
.
c
+q
Manufacturers-or
"
6
,
~
\
t.
\
,
\
:..
I
’
cl
.’
\.
~
.
1
.\
‘,
I-.
I,
\
sheets and extruded
sections
to be
Some companies produce rods,
They may be a&attractive
market to the
used by fabricators.
recycler
because they,operate
at high volume, but rarely
have .as +
.
much flexibility
to vary product
quality
~$3 moulders
who know,
accurately,
the final
market for“the
product.
'r
,'
.
.I
Other
a
Manufacturers
specialists
but employ mould',Lt g'
Many companies are not plastics
For example
operations
in the manufacture
of some other product.
shoe and 'boot makers use plastics
extensively
and may carry"~out
the various
plastics
moulding
operations
in the same production
Many
canvas,
rubber
etc.
sequence' as the work in leather,
manufacturers
use plastic
packaging
machineh
at. the,end
of a
production
operation.
.
.e
Fabricator8
The plastics
'
-4....'--
.
.
These firms cut and join sheet,
rod or &xtrueion
to manufacture
a'
They
have
no
opportunity
to use reclaim.
(
variety
of products.
P
Machinery
and Tool Rakers
=a
/
mention
industry
justifies
One other
sector,,'of
the plastics
The
makers
and
suppliers
of
although
not customers
for rec$aim.
plastics
manufacturing
machinery,
tools,
moulds and dies are well
'informed
about who does what, who makes what and who uses what
who is
They may advise
industry.
within
the local
plastics
likely
to buy material.
.
.
c
f
?
!?
L
c
trade'.press
+
e
,I
.&.
i:
3
There are mar?y'magazines
about plasti&
Most accept advertising
for the buying. or sale.of
secondary material.
Anyone,considering
'industry
should
read these (ip
entering
the: reclaimed
plastics
., If
the local
library
"if
a subscription
is too expensive).
material
cannot 'be sold through
other
methods,
a small' aa've.rt
"Work ,:f$om
offering
secondary
polymer
is a good investment.
.Waste" includes
advice about the wording of such advertisements.
.
I
P*
*
The Bibliograp&
includes
a list
*
-,
4
of plastics
'i
E
trade'journals.
,
' -
-'
-
.
1
’
a
.
.
.
7
.
,
GIVING THE CUSTOMERWHAT HE WARTS
CHAPTER 3:
whatever
the price
charged,
Some;business
markets are "captive":
Public
companies
that
the customer has to pay or go without.
electricity
or
mains
water
are
in
that
fortunate
3upply
gag,
the
In other businesses
the reverse
'may be true;
3itua"tion.
customer
has--a
satisfactory
alternative
product
available
and
Recycled
plastics
are
needs strong
persuasion
to buy yours.
Only by offering
a reclaim
that
is
definitely
of this -kind..
substantially
more attractive
than new or. "virgin"
polymer
can
,the recycler
hope to obtain
and hold a market.
. This chapter
considers
the difference3
between virgin
polymer and reclaim
and
~0
what ia needed to make the latter
marketable.
l
-..__
.
e
.
'0
.
Price
.
a,.br
.
The main, often the only,
reason why.a customer buys reclaim
is
The use of reclaim
in the manufacture
of
because it is cheaper.
either
capture
orders which
a product.or.material
means he will
he would otherwise
have lost
or will
make more profit
from the"
sale.
The factors
that
determine
the price
of reclaim
are,
therefore
of the greatest
importance,
L
The price
can be set either
by what the customer, will
pay or by
The latter
can only be 'used for
what it
costs
to produce.
captive
markets;
the former rnu3.t be used by the r?cycler.
It
can be calculated
@'follows.
r
4
The amount of persuasion
the customer will
need to use reclaim..
can be expres'sed as the Reclaim Price* Advantage
Ratio:
* -.
r
9 = Price
Price
REPAR
+
p aid
paid
for
for
rec1aim.x
equivalent
t’,,.
1
,
i
_
‘@
..a ,
‘:
r
virgin
I .
-1n-
h
material
'
.’:
P
(
*
-(
.
.
I i
_a':
~
.
fi ‘,
‘:
.,
.
:a
100%
It is found by experience
and by study of the market situation
and of the quality
of the reclaim:'
If,
the
for
example,
customer's
process needs 'great
purity
and reclaim.is
likely
to
cohtain
occasional
particles
of sand or dust, then the REPAR must
be rather
low. ‘If however the reclaim
is almost as satisfactory
as virgin
polymer a REPAR approaching
l'OO% is possible.
Indeed
if the virgin
material
"cannot"
be obtained
at all then the REPAR
may even exceed 100%: 0a situation.
not uncommon in developing
countries
with strict
import
controls.
Normally
the REPAR will'
vary between 40% and SO%.
,,. )
b
The price that the cuetomer,.would.have
to pay for <irgin
material
F
can be found from stockfats,-or
compoundersJ
1'
._a
'h 1
- I
1:
. .'s
1a
. *
3
*
k
,,3
,‘.-y
FI :
.-
I
.
The price
be:
that
Selling
the
.5
recycler
will
ask from
= REPAR x price
loo
price
the
of virgin
customer
wil'
then
resin
This is not dependent
on the recycler's
production
costs and if
these costs are greater
the recycler
.is faced with a diffiqulty.
either
he can ask 'the customer
for a higher
He has a choice:
knowing that
it is not likely
to be given
(unless!
his
price,
,estimate
of.the
REPAR was too low,) or else he can decide not to
A "third
collect
and recycle
this
material
for this
customer.
option,
to sell at less than production
cost, should not norm&lly
be accepted.
(*,
J
‘*
Example
.
.i' **.
'a;
',
'
,
.I'
/
Because the product
is large
and of low quality,
'&th
thick
the
customer
will
not
suffer
technically.by
using
a
sections,
and will
make large
saving3
in his
high proportion
of reclaim
Therefore
a [email protected] of 70% .a /
material
costs? which are substantial.
could be tried,
giving
a selling
price of $600 x 70$%= $420, well
/
above the .recycler's
costs.
a.
.? /
'.
Example
.
/
A customer manufactures
polyethylene
shopping
carrier
bags on a
What price should the recycler
ask'
blown film extrusion
machine.
if virgin,materia'l
sells
at $700 a tonne and the recyclor's
"costs
are $350 a tonne to produce clean,
reclaimed
pellets..
'
.
.r
Because the film blowing
process is sensitive
to the presence of
tiny specks of dust or grit,
and material
costs are low compared
with the very expensive
machine costs,
and because some of the
'film
may be used for high quality,
printed
packaging,
a
low as 25% ~$11 be needed. fo tempt the customer.
The
price will
be.$700
”
.,
Y
A customer manufactures
low cost polyethylene
buckets
on a large
Wpat price
should the recycler.ask
injection
moulding
machine.
if virgin
material
sells
at $600 a tonne and the recycler's
costs
'are $300 a tonne, to produce clean,
reclaimed
pellets.
"
.
'-.
' _'
x
25
1.00
‘T
=
-
c
I
.
$175
.
,
1 .
F.,.
n
it
and this
is 30 far below the recycler'.s
cost3 that
worth dealing
in this
material
to this
customer.
However #the
recycler
may like to calculate
what RE'PAR is necessary
for such a
,
deal to be profitable
and-it
will
be:
\
.
-
Minimum
REPAR = Cost of reclaim
x 100
.
, Price of virgin.
/
.
-19-
I
‘.
:.
‘Y
i
0
*
/
,/
i
;
”
.c
.a
In
this
example:
-.
,
minimum REPAR = 350 x 100 = 50% which
’
would
700
.I
‘.
only
very
0
__
be achievable
under'these
difficult
to obtain.
conditions
if
virgin
-s-
%
*-
D
Availability
'i --..__~
The situations
-
('.:
'-
/
in'which
'
t
. B
ti'rgin
f
c
J
material
is not
material
J
I
'
*
“
/'
.
.
Where' the
product'.
cus'tomer
gets
unexpected,
heavy
a
,I
.\
.’
..
are,:(as
etc.
l>
‘.
I
to
Where customers
are remote from‘ suppliers
of material,,
transport
is unreliable
or delivery
times lengthy.
sr
.
.\
Where stockiats
or compounders are unreliable
or simply
run out of stocks.
-
5
1
\
available
Times'of
real or imaginary
international
oil crisis
in 1973/4) due to war, oil producer 'pric^e cartels,
*
G
I. , '
'Times of national,
import
restriction
due, usually,
foreign
exchange pressures,,
war, etc.
were
.
i
.
:
,\/
.I’
,/I
demand for's
,
The reclaimer
should,be
constantly
alert
to such situations
and
exploit
them.
In l/973/4,
following
the OPEC crisis,
reclaim
was'.
selling
inBritain
'at.a REPAR greater-than
100% for a short time J
.political
situations
common in certain
and in the turbulent
countries
such op,portunities
may occur frequently.
/
A----7
1% is also:!:,."
Availability,
however,
is a two edged weapon.
necessary
for the recycler
to prove to hi-s custom&
that he L&I
have material
available
in adequate quantities
when it is needed.
This. may make itnecessary
to collect
and produce m-ore than can
be sold at ,one time and stock the balance in order to offer
rapid
deliveriea'when
these are called
for.
Be .will'ing
to deliver
small .quantities
on a trial
"basis
if a, moulder
or compounder
temporarily
runs out of virgin
materiali
If he is satisfied
with
he may then order
it -on a regular
the quality
of the reclaim
basi3,
initially
using very small proportions
in his compound but
slowly
increasing
the3e to progressively
cheapen- his. product.
Only if he is making his o,wn moulded producta.
(see Chapter 6)
should a rkcycler
consider
production
of less than one tonne of
reclaim
per week:
\"
3
.
.
d
,i
'-
---
.'
:.
.
:
‘,
- Definition
Quality
The two previous
matters
have been,essentially
commercial.,
The
The recycler's
objective
is to
remaining
ones concern quality.
produce-reclaim
to satisfy
the customer's
needs, and thereafter
maintain
both quality
and 'quantity,
at an,economic‘
cost.
To
achieve this he will
probably
need to produce reclaim
as near to
the quality
of virgin
polymer as is consistent
with low costs of
production.
1
The first
essential
is that 'the material'be
clearly
de-fined,
so
that the customer
quickly
appreciates
.what uses it‘might
have.
The definition
may be provided
in a number'of+diffsrent
ways:
:
Source
a)
.
What were the producis
and preferably
rho made
-3.. .
them in the first
place?
.
-a
It may be sufficient
to say what w-as the source
of the secondary material.
This"should
include:
..
Where were they
How have they
-
JI
obtained?
been subsequently
_-
-
-
processed?
Thus a satisfactory
definition
might be:
"PVC
sold
in
cooking
oil
'bottles,
as
Supermarkets
in Manila,
Philippines,
washed,
granulated
and free from caps or labels".
b)
Material
4
It
may be ;betterto specify
the material
composition.
This i$ not always possible
b u t
if regular
quantities
of a few standard
wastes
are coll\ected
it may be possible
to trace them
,back to the moulder and obtain
the.information
'-from him; indeed he may be pleased to. buy the
A ztisfactory
definition
of
reclaim.back.
*
/'
this kind might be;
‘.
./
.
.
"PVC containing
30% nitrile
2% dioctyl
tritolyl
phosphate,
and .2$ titanium
diqxide
pigyent".
c>
-,
Properties
.
./-
rubber,
,3O%
tin
stabilizer
Finally
it may be possible
to define a material
*by its
propertiesand this
is often
what a
is specified
compounder does. The basic resin
by name but the effects
of other
ingredients
may be simply reported,
for example:
,
I
"High density
polyethylene
of specific
gravity
tensile
strength
386
Kg/sq.cm.,
0.957,
elasticity
.9100
Kg./sq.cm
;and MFI (melt
.flow
index)
0.5Gm/lO min. at 2.16Kg load".
, ~
1
i;
.
-
-2!-
f
’
1
c
.
To d%ine
a &iterial
have a good technical
laboratory.
-.
in
this
w:y it
understanding
3
is obv?&sly
and access
n&essary
to
to ,a testing
T
..--.
':
The less experienced'recgcler
will
'begin by using the definition
and expertise
may venture
by source and, as he gains confidence
It is worth remembering
into more scientific
procedures
later.
that many small moulders
do not themtives
know anything
about
the materials
they are using but ~rely- on a supplier
or compounder
to provide
what is correct
for- their
need+
b
In many small factories
reclaim
will
be defined
Trial
and
'd)
.by whether
or not it produces an adequate proerror
r
Thereafter
the only
duct
without
trouble.
definition
will
be "the same as before".
Purity
i
7'
The -second
essential
One single
Npureti.
or non-thermoplastics.
is that
reclaimed,
type of thermoplastic
This is because:
.
polymer
needs
,free from other
to be
types
,
Impurities
can.spoil
the properties
of the product
leak
re-'
resistance
to
chemicals,
strength
and toughness,
The harm
appearance.
visual
especially,
sistance
-and,
resulting
is more than just 'one or two bad articles
or even
the inconvenience
of having
to replace
the defective
item.
It is the damage to the moulder's
reputation
for quality;',
as
a result
of which he may fail
to get future
orders,
may be c
inspection
of his goods when
subject
to unduly
stringent
delivered,
forced to reduce his prices
etc.
.
l
Blockages
can lose production
time
- The ,main problem
is
obstruction
of nozzles
and screens
(fine
wire mesh strainers) by non therm0 plastic
impurities
such as i'grit,
sand,
=.j paper,
especially
Labels,
adhesive
tape and paper labels.
variety
used in supermarkets,
'are
' the tiny
se&f adhesive
because they are so small that
among- the worst
offenders,
for example
Metal foil,
sorters
may easily
over$ook them.
tops'of
milk annd cream cups, is also troublesoge:
Althoughcdn be removed they .play
havoc with
the
such blockagee
economics of the production
proce-ss.
_/._- -- _--.
Pt is aimed at
Plastics
moulding
is a modern industry.
exploiting
the incredible
advantages
of plastics
over other
ease of moulding
complicated
materials:
lightness,
thinness,
shapes, bright,
varied
colours,
speed of prowon
and low
labour
requirements.
These are achieve&-y
designing
and.
building
manufacturing
equipment
of !enormous sophistication
and complexity.
,'
_,_
,
,
,
_).(,/
.
/.
'
_
>..
-22l
i.
I
I
.i’;\i
.
‘,‘..
I,(,,_
Such equipment
is very expensive
and can only
"earn
its
'keep"
and produce
at low cost .if
it
is
kept
running-continuously,
often for twenty four hours a day, seven days
a week.
Thus an obstruction
or breakdown destroys
efficient
manager.
He
- operating
economics and annoys the production
would rather
increase
the product
cost by 55, by using a
safe raw material
that
is 50% dearer,
than increase
the
costs by 15% by having his machine out of operation
for four
hours a day while blockages
are-cleared.
r
Impurities
&A interrupt
p reduction
in other
ways than
blockages-:
The most common occurs
in the production
of
It has been expl'ain'ed how the film is
extruded,
blown film.
If a piece
developed upwards in a tall,
continuous
bubble.
_.
of grit- or e~B~~-pnnct~~t~~u~b~e
itm%ybuit
and
Thick film (e.g.
the whole operation
must be set up afresh.
fertilizer
sacks)
is less sensitive
,than" thin
(e.gd
shop
bags).
'
- ~~ ---
,
~'-_.----------
__
.-i
G--.
1
___.________"________
- .-Plastics
.-maohinery-Permanent damage and wear. tomachines
is designed
to handle 'soft.
solids
and fluids
under high
pressures
and moderately
high temperatures.
In these conditions
hard grit
or metal can score or wear moving parts
and have serious
long term effects
on the'efficiency
of the *
machine.
(I
."?
,
Cleanliness
In many ways cleanliness
of a material
is the. same‘ as purity.
However the consequences
of material
being dirty.may
differ
from.
those described
above.
For example oil or food residues
may be .
absorbed into scrap plastic
and, altho gh they may not cause any"
of the problems described
above they
or
P ay spoil, .the appearance
create. a.n.unpleasant
smell.
Because it is impossible
to know how
they have been contaminated
reclaimed
materials
from an-unknown
source
toys
fiFshould
NEVER BE USED FOR foe-d packaging,
children,
kitchen
utensils,
drinking
water pip&g and tanks .or
clothing.
I
.
._. r.
.~
5
:
-s
-
I -Y----.....
Quality
Reduction
r ..
a recycler
has supplied
a customer
of reclaim
and knows him and his needs
to reduce quality,
purity
or cleanliness
harm to the customer's
product)
in order
When
This should be done~ cautiously,
attention
to the customer's
any problems as a result..~
If
the customer
demand reduction
is aware
in price.
._.
"
a
._...
a little
at a time, paying close
reaction
and whether he encounters
of
reduced
.&
.
with several
quantities
well,
it may.be possible
of the reclaim
(without
to save costs.
,
q.uality
he I will
.__I._II--_. . ..---__--_. ..r-
usually
_I__ .__. -.. ...I....,.' '.-
,
.
Particle
size
'
and shape
Virgin
polymer is normally
sold either
as pellet
or as powder.
The pelleti-are
of uniform
sizeand
'shape~~about~the
tie-of
The powder is of consistent
grain size.OConslstency
ma"i.ze grain.
the density
of the material
in
is important
because it decides
which in turn d,e,ter&&es
the-Qen&tp
w---:'
the moulding
machine,
Particles
of different
dizes and shapes
strength
of .the product>.
1
or areas of incomplete
fusion
result
in-air
spaces;' gas bubbles
Solid plastics
scrap
(due to unmelted material)
in the product.
that has been passed through
a granulator
tith
a grid size of 4mm
.or~6mm will
be equivalent
to virgin
pellet
and will
mix with it,
The main
even though the granules
may be irregular
in shape.
Granulating
this produces
/"problem
comes with thin film or sheet.
it- is not dense enough to .fall~
--e--light
flake
whichx~3Eause
freely
down the sloping
sides
of a moulding
machine
hopper,
causes the machine intermittently
to run out of material
and feed
It is necessary
to turn.
often with probfems of overheating.
air,
such material
into
crumb or even cylindrical
pellets
and' these.
operations
will
be described
'in Chapter 5.
SmaZl particle
sizes
are economical
materials
occupy more space and are
store.
to pack.
expensive
i* ~.~
~~
:
L
I
-
rm
.~ i
'i
:
i
2
4'.J'
Large particle
to transpw,an&-+d*/
‘
/
Colour
When they
are produced
from
raw materials,~~~~pol~~Ps~-ar-;1~Their
final
c,olour is obtained
by
colourless
or fa.i%tly
yellow.,
mixing with heavily
pigmented masterbatch
which is expensive.
By
colours
it
is
possible
to
sorting
plastic
scrap into
separate
. produce a coloured
reclaim
,whose use can save the moulder subThis adds ~to the competitiveness
of
stantial.
colouring
costs:the recycled
material,-i&re&ses.its
REPAR and the price that canbe asked for it.
Such advantage
is only gained if the recycler
liaises
carefully
with his customer and adjusts
his colour
sort'Products
that are black,
dark
ing to match the customer's
needs.
i grey or dull
green or brown are very likely
to have 'been: made
Refuse sacks,
garbage -cans,
a from reclaim
of mixed
colours.
---.
buckets and jerry
cans are common examples. --- -----
~---
.
'
'.
_..... ----
I~ ~~-~ ~.~~
---
*
._.~ ~..----------
'
_.
Pa-eking'
Having produced a clearly
defined
material;,of
good quality,
the right
price
and available
in the necessary
quantity
at
right
time, the recycler
must not forget
about'the
packing.
only is it good commercial
practice
.to make your product'look
good (the packaging
industry,
biggest
user of plastics
in
world - is based on that principle)
but'packing
must;-.
"\
be strong,
so that it does not break'open
during'transport
or storage.
#
f
1.
.
.
.
._-^.
--
,_____
_* -.....-.___--.----
--.-.‘---..--..-.~,
----..
-241
_____
1_
-__._
___.lll-F--
-___._
.
-.---
.
._..
_--^
_.....-.
,
at
the
Not
the
~..
.." . . . ‘.^
(
. . . . . . .,.......
.
_,.__....
. . .
41
).
-’
__-..
_-.
._..-.
I-
--
---
,
9
f
a
.
.
.
b
D
so that nq'product
Be leakproof,
other , contaminants
are kept out.
-7
-_
__~
lost
and water,
dirt
or
_~
-_.__
/
~___~
so that the customer and the recycler
Be of standard weight,
have no argument
about the qu-a-ntity
of material
thatbas
1
been delivered.
'
-
___
-~-~
is
':.--
~.
._ _~
-'
.,
for
ease of storage
and transport.
*> SacksBe stackable,
should- be fairly
flat .so that
they can be stacked .ten or
Drums should have flat
lids for stackIngi
'*
twenty I+gh.
0
_~ ~~~.
~.
\
commercial
prtacCarry the recycler's
name.
/',
ional
and bueinesilike.
cI'
tice,‘lmakes
the company 1
_.l-..,....
...".
_~
-,_&
-~
I I_nd polymer
sacks':
Initiallyi&may
.be sensible
"These can ei.ther
often a customer will
be able
or, *'better,
heat
be stapled
at the top to 'aVeal them securely
Later
Simple heat sealing
machines are not expensive.
sealed.
._..-., _. . _ .___.__
"printed
investing
in new sacks,
it
is worthwhile
with .' tk .-.._, __. _
,( ,,,.
plus the weight and description
recycler“s
tradename and address,
,,,. ..I.
The businesslike
appearance
is worth the extra
,,, ,,,,,,., ,.
of the material.
cost.
I
I”
s
’
a
I
’
.
*
.
.,,
’
e
.
..t
I
,
;w
:
‘,
.I ? .
.
I
‘. ,I.
.I-‘-‘-’
,
‘. ..+.....
..
I
‘I
#’
.
r.
‘“;
1.
._
WHICH PLASTICS TO COLLECT AND RECYCLE
_
'-r
i
structure
and~proceaaea
of
Kaving'\studied
the polymers,~-prod-u&a,
.,~
the lo&l
plastics
industry
and, the conditions
under which it
*"
be able ..to d.ec5d.e. .. .,"... .' -'
w+
which plastics
to collect
and :proceqa.
It is stressed
that all
rules
are.generalizations;
.._..
may .,,.c.!e33ei...them,. FM..
local...situat.ions
,
example. Rule '.j would
not apply
if
loc%l
facto-riea
discarded
I, *
=
plastic
foam s~rap(e+g~~&om
=$%rG&r*&~hd
loca*--:-+=
.-- ,_
,,,I,,,
I ,.,
induatriep
existed
that could use it e.g. ,toy_or cushion making,.
*
t
.
'
plastics
bonded to fabric,
Do not c!oll,ect
laminates,
Rule 1
paper or metal or reinforced
with glass fibre
etc.,
or
/
thermoseta.
To teat whether a plastic
is a thermoaet,
see page 43.
,).,-,_,,,
,?~
..__...,_,.._..
,,:..,,.!.?.:';'::':':'I
\-_,(,,,,, .., ,'.-'.' ,., . .-....,.
.I _._...___I
;‘,
\, \, , I /, \, /, sI \ 1, ~, x\; /',', %I, ~\ \ >
Do ,not corlect
articles
TQhich:.
RuTe 2
2
:---
iccep
pee
_
a>
b)
.Have the plastic
mixed with,
plaatica'so
that it is difficult
e.g.~ carp&g,_-blister-packaging.
or
joined
to; norito separate
them:
T-P
7-
~--
Are made of plastics
that are hard. 'C o'identify
expensive
items such aa'those
in the / th,ird
column of Table 3 on page:72.-
mainly
c>
---I-
-/
-Rule 3
Are commonly
articles.
'for
.
': goada.~
-
soiled
babies,-
or unhpeipic.
and__.an-i-or
~.-~
-
'such' as
hospital
*_'.
~.~
, ~~-
The costs
.
Do not collect
foamed or expanded plastics;
of transporting
these high volume materials
will
not,.
be recovered
by the value o sales.
The oniy excep4
tiona to this
rule are where there.ia
a clear market
to use them in the foamed o expanded state
e.g.
as ._ ~-I.- * ~.__,,
Even-then,
, tl ,fillings
for
so,f~~l:.goads...os-.as-insulation.
,_
,__._._._,_._.
G
_
_
-.-.-.
_
_
_,_,_.i._._
___- - -.-.-___-.,
--'-'--'-"~'-'-"'-- check carefully
that
the I&ice
offered
is enough to
c
cover all
transport.and...col$ection
costs and';-sell 'by
volume (cubic
feet or cubic metrea) not by'weight.
:
Rule 4
DO not
collect
film
scrap
unless
you (or
your c
customer)
have the apecialiied
equi,pment for crumbing
Eveg
f&n ,,‘c,-,....
_,_._
,_-.
..:... ...-.-...‘...-...-‘-.-.~-.....i
or "agglomerating"
5. _,.,...........
it~. ,...-'see
I-,-(-.-,_,_,_
. .,.. . . _. . __._._,_...
I... . .Chapter
..
. . I . . . _,..
remembe,r-.that-'f~~~.~Aaa
great
surface
area for little
~'
weight;
this
means that
the area which can become
.dirty--o-r
eontamina&ed,
-,
. ..carry
adhesive
labels
or,,tape,
--is very large
so there may be-more' of'_~~these- trouble
'.
___~~
---Bomi7iiiipuritiea
per-kgof?lymer
th&
is the case
,,,,,....,
,..,....,
,.
.
Moreov&,...bebauga
..film. frequentlywith ahid
'toes
.:. &."' ...~.c.~+p~ ~.-.
,,.,__.,,,.".._
,._..,.. . . . .~,_,..r
,.s,l,P,,,ll-l...~.--‘
--_-~-2--.~
_
form &-bagi~
and- sacka, there 'will
!co~only
,
_I-~
- ~.~_.. ._ =
be residues
of the former contents
left
inside.
~,.__~
.i_~z ---i-.
@I
All
such"'impurities
must
time consuming and costly
yield
some small reward-if
be--reused o-r sold~.)
.
Rule
Rule
5
6
4
be removed before
sale,'
a
procesb (which,
however may
the residues
themselves
can
'.
~~.~
-.~
'*
~~ ~-
Collect
only those grades and polymers for which.there
The next stage is therefore
to check out
is a market.
and the whole business
of
what markets
exist.
This,
is covered in some detail
in "Work
marketing
wastes,
only be outlined
here:"Work
from
from Waste" and will
a detailed
case study of p&a-atica
Waste" also contains
recycliclng..
%ind (from the telephone
directory,
Ministry
of Inmachinery
suppliers
or other
sources)
which
dustry,
companies in your district
use plastics.
Then assess
wheth-er
they
are likely
customers.
This
may be
for example by conversation
possible
without
A visit,
with
a plastics
machinery
salesman
who knows the
1:
c territ,ory.
It may be necessary
to visit
one or more
factories
and discuss
with
the manage&.
Then-~ch,eck .:.‘, %,.,___,. ~~I,_ _,
the kind
list;
Table 2 (~70) may -be used to identify
of factory
which is likely
to be a good customer.
.a
/,- . ~~
'.,.
,
'Collect
materials
that are abundant
in your area.
In
particular
consider:PVC for sale to manufacturers
o? flexible
hose and
plaaticiaed
pipe.
These
low grade,
thick-walled
of polymer.
Manufacturers
are '
products
use, a lot
pleased ,-_~Lto use __.
a high percentage
of reclaim
for the
~- TCYwt?F
j%lce .anrquaIFty
rapge if they can overcome the I
technical
difficulties.
Common wastes
that
are
suitable
are:.
a
Soft, flexible,
plaaticised
PVC, from footballs,
ladies :.
Suitable.
wastes
are:
luggage.
handbags,
and other
a clear
amber (yellow), _.cooking
oil
bottles
- often
shampoo and other pharmaceutical
bottles
(transparent
bottles
with sales appeal).
1.
2.
?
Unplasticized
PVC for'manufacture
of rigid
irrigation
and drainage
pipe,
gutters
etck Again a high percentacceptable
for
the lower
is often
age of reclaim
quality
product.
\
j
.,f
,/
I
!il-'\,
1
!
I
i
3.
.
High density
and low density
polythene
'from a wide
range of housewares
such as buckets,
bowls,. brushes;
~- (Gut out the bristles)+laundry
baskets etc. These are
.I
contain
good
discarded
by hbusewives
when
__.~~
~.broken,
~~-----i----weights
of poiyu66,
i'r%y-from
-adhesive
labels,
met<?--..
caps or .otheri contaminan&.
___ _, I _,,,.....I
'-"-'.
?\
I
1
/
9
,
‘__~~~~
.
?
:
b
I
’
I
The manufacturer
can reuse them to' make similar,thick
low-quality
with
a market
among
products:
low-cost,
the poorer people of the community.
4.
Low density'
polythene
bottles,
distinguished
because
they
are a pearly
white
colour,
translucent
(not
Also opaque,
white
or
opaque but not transparent).
coloured
bottles,
of the "squeeze"
type;
~_ 3-.~;~~~~~-~or-~u~~~~l~.~-~-~neaeof high
density
polyethylene
rigidity
despite
the thin
or c.oloured.
_
opaque, nhite
6,
to give
walls-and
.\
...__._._.___.__......
.I..
are -made--btrength
and
:
ar'e bright,
,
\ .
\
‘I
White polystyrene
tubs, cups, plates
and food contain-‘
'"
ers,
such: as used by fast-food
stores.
These' are
thermoformed
from polystyrene
sheet
and cannot
be
recycled
for this
purpose but can be used for other.
such as ladies
shoe heels.
They
polystyrene
product3
are very thin
and occupy a large volume but' can be
or
one inside.
another
or can be crushed
stacked,
.' shredded
by hand during
collection
to reduce volume
'and cheapen transport.
~~~.~
-~ ~Crystal-clear,
BET drink'bottles,
often large,.usually
7.
with
a -base of black
polythene
or other
material.
' These are widely
used in Europe and U.S.A< and may be
recyclable
for 'manufacture
of polyester
fibre
(e.g,
fillings
for sleeping
bags) when the base,
cap and
1 :
( labels
are removed.
~~
8.
Some types of industrial
scrap.
.
Recycling&&-mixed
$3
plastics'waste
'i
,.
r
'
1
ng the past ten years
a significant
technology
has been---.
~. -de eloped .Fn Europe and Japan for 'the recycling
of mixed and
dirty
plastics
baste into large products
of<low quality,
such as
building
boards,
cable tiume and pallet3
(Fig? 11). In
fencing,
general
it has not been commercially
successful
and further
development
is needed.
A variant
of this
by a German company,
Remaker, has been more successful
but the machinery
is very ex- "
pensive by comparison with the equipment described'here.
A full
description
may be found in the Bibliography
-%Ref. 13.
v
z
*
la
’
a
Figure
Other
jl
11: Large
dirty
plastics
products
of low quality
made from mixed and
plastic
waste by a Japanese process.
recycling
technologies
Ref.
15 describes
many other
plastics
which have been developed
but none has,
application
as the methods
used to reprocess 400,000 tonnes of scrap
!:C?
recycling
technologies
widespread
are
ic perannum.
such
pla,
'
TABLE 2
:
CUSTOMERCHECK LIST
DEPENDING IN WHICH COLUMNTHE ANSWERLIES:
[email protected]
----_-_______-_-------------------------------------------------L
-. PROSPECTBUT
GOODPROSPECT, ASK
TRYiBETTER
THE NEXT,QUESTION
_a
ONES FIRST
__i_________________-----------------------------------------------------------How close is
Far
Close
their
factory?
%a '
~-----------------,---^---------------------------__--__--___-----____~~~~~~~~~~~
Compounders,
'&at kind of
.,
Stockists,
factory?
Moulders,
- Converters
POOR-PROSPECT
Very- far ._
Raw
material
producers,
fabricators
1
'2,
\
',',..
_____________-______________,________,__---------------------------.-------------~
'fiat materials
do they use?
Thermoplastic
powders/pellets.
,I
--w-w ~-------------------------------------------------------------------------1.
Plasticised
PVC
Common thermoWhat <polymers do
i
Less common'
*
plastics
ie. HDPE '.
they:use?
thermoplastics
LDPE,PS,Rigid
PVC
ie'.PP,Nylon,PC
1
_1
Others on ~12.
-------------------------------------------------,------------------------------Blown film
'i?hpt processes
Injection'moulding,
extrusion,
do they operate?
Extrusion,
5
Blow moulding
i Callendering
sasting
1
.
I *
.Others on p8.
-----L------------------------r-----------------------------------------------What kind of';
Non-food contact
' and other products
products do
they make?
'
without
health
risks
-------~-----_--____----------------------------------------------------------What colour are
Black, dull green,
products?
brown or dark grey
----^-------------------------------------------------------------------------Domestic or
.
What quality
of
product?
commercial
quality
IF STILL IN THIS
COLUMN YOJJHAVE
A GOOD CHANCE TO .
SELL TO THEM
q
.'
Thermosets,
Thermo-plastid
~ ',
rod, coil, .%heet,
extrusion.
Other O1
specialized
polymers
Thermo-forming
Heat sealing
Fabricating
Machining
! --Food Packaging
Drug containers,
Toys,
'
Surgical
goods
hospital
goods
Crystal
-
clear
High
quality
'7
or specialised
1. i
!
CHAPTER 4:
COLLECTION OF PLASTIC WASTE
Almott every establishment
used by people is a source of plastics
streets,
shops,
factories,
hospitals,
schools,
homes,
scrap:
Sometime3 it lies
loose as litter,
parks, beaches and many more.
sometimes
it is collected
together
,and stored
in a container.the sources from which plastics
waste
This chapter
will.discuss
the methods used-for
collection
and transport
can be obtained,
and the cost of the collection
process.
It is summarised in Table 7 (~72).
SOURCESOF PLASTIC SCRAP
Homes and Households
The main wastes
-:_-
5 to 10. Usually
of HDPE or
Broken housewares - See Figs.
LDPE but top quality
may be nylon or PP, lower quality
PS.
Rottl&,
-
usually
Food containers,
Film,
-
are:-
Bottle
but if
sacks
mainly
and bags,
9
.
of LDPE or HDPE, PVC or PET.
HDPE, LDPE, PS, ABS.
mainly
of LDPE, .HDPE,PVC, Polyester.
be of HDPE, PS, PP, or even thermosets
caps -‘may
difficult
to identify
the polymer,
leave them out.
Damaged household
cooking utensils,
appliances
- fridges,
telephone
May contain
many polymers.
etc.
sports
Damaged handbags
and luggage,
footballs
etc.,
and leather
imitati'on
plasticised
PVC.
goops,
clothing
handsets,
especially
mainly
of
",
most
Shoes and sandals
'- often
the sole
is plastic,
commonly plasticised
PVC but also polyurethane;
sometimes
the upper is plastic.
If it looks like
leather
(but does
not smell of leather)
it is probably
butadiene
- qtyrene
copolymer.
Waterproof
garment3
cyclable.
If
of
easily
recycled.
-
may be of
plastic
coated
plasticiged
fabric
they
PVC', and reb
cannot
be
Toys - may be of any,polymer.
.
I
/
.
TABLE
3 -RECYCLABILI'l?Y
bF PLASTIC PRODUCTS '
*
The following
list
is neither
dcanplete nor unalterable
but indicates,
'D j
*
"sources
of waste plastics:
3
4 >
-I
Qbstacle
to
These products
These products
2
,
recycling
not generally
.
generally
recyclable
Source
, recycled
because:
if clean.
--"‘.'-""""""""'"-"
-------___-----------------------'--"f""-"'"-'
Blister
packs
9~ Plastic'mixed
- ,iri Shrink wrap,
Packaging
with other.
home or store bags,.
materials.
food containers
i
-4
and tubs, drink and
.
/
e '7
(I
n
,other bottles..
I
__________-_________-----------------------------------------------------------Smali
"
Camek as; radio,
T.V.
Housewares - buckets,
In the home
quantities
and recorder
oabinets
wastebins,
bowls,
of varied
\
brushes,
pans, baskets.
plastics
*
mixed
with other
Parts o-f domestic
Tableware and cooking
_c
materials
appliances
r
utensils.
Telephones
!‘
I,
Jewellery
','
'
Fabrics,
yarns and
i
clothing
(but these
.
L
may be better
re-.
\
cycled as textiles).
Babywear
' diapers,
\
4
Handbags,
luggage.
’
footwear,
Toys - building
balls.
bricks,
t
i/
Gramophone
Photographic
audio-visual
and film,
.
records
and
_
tapes
u,
P
s
.
‘r
--------------------------------j------------
--c-----------------------------------
Outside
home.
- plastDc
pants
Soiled
cot sheets material.
bibs,
I
Furniture,
foam fillings,Mixed with
other materi
: carpets,
matting.
\
\\
b
','i,
'\
*
.?
\
\
;
~..:. \
models,",
Wide variety
[email protected] -' dolls,
\
of piastics.
g'iunes
used. Hard t
*4
<
I identify;
often mixed
with other
,;:* materials
0bti.cs ? spectacles,
. binoculars,,,
telescopes,'4
I
*
the
and tape
Rope, string
Office
and school
equipment.
-*-"'-"""----""'"-""-"'--"-^'-'-----~---------~.~-----------------------51
8, Pro,teotive'
clothing'-crash helmets,
gqggles,
visors,
gloves,-boots,
.'
*
II
*
i
TABLE
:-.
3
(cant.)
>.
1.L
:
These product3
These products
*.
not generally
generally
recyclable
S>urce :
\
recycled
because:
if clean
A,--_________-__--------------------------------,m ----------------Sport3 equipment homeSports equipment Outside the
raquets,
padding',
skis,
'
footballs,
bats.
home.
diving
.gear,',surf
boards
Ii
k
P
.
Inflatable
boats.
4'
‘\,
Hosepipe,
plant
..
--_^-_---_----
Industry
pots,
*
’ . m----e-
-----‘--“----------
Pip&work,,
packaging,
formers;
cable.
Container3
and
handling
units
pallets,
crates,
stillages,
bins, boxes
drums, barrels,
jerry
cans.
-------------'-"-"~--"-'-----------,---------Water pipes,
fittings
Building
and gutters,
wall.and
A
; roof panels,
skylights,
light
fittings.
%
\i
- I
I
Boat gear - buoyancy
.aids, sails,
masts
& rigging,
fittings.
.
.
,
Ii
---“‘-‘-“,-““‘-“‘-
--_--__-----------
Industrial-equipment
tanks, vats, vessels,
-
U
~
Electrical~fittings,
Signs, advertising
Adhesives,
coatings.*
_
'paints,
metal
Laminates in furniture
fittings
and paneling.
foams.
i Agriculture
Tanks,
*'
'
\
'
-a---_
--mmMixed with nonplastics.Thermoseta.
._.
m
*'
Boams
.
i*-------e-e-,
Permanent
',
-L
'structures
t
i
---7"
_I
- .Mainly
'$,
thermoseta
'.
greenhouses.
Thermosets:'
Permanent.
*.Bonded to
non-plastic3
-,-,,,,,-,---j---_,,,,,,,,,_,,
Reinforced
structures.
Insulation
Irrigation
piping,
hoses, .sheeting,-.sacka,
I
rope, string,
Jerry.,
cans, drums barrels.
-,,,,--------~----------~------------,-~*--~----~----------
. VY
'Workshop tools - handles,
drill
bodies.
"
.
Automobile,
train,
and aircraft
bicycle,
parts.
' 9
i,\ ------------r----------------r--------------------------i b
\
I
a
Garden-tang,
%e'furniture,
stakes.
fittings,
cable.
1
---------e--M-.
Wide variety
of plastic3
used: hard-to
identify,
often mixed
with other
* materials
1,
8
',
Electrical
:lioxes.
Electrical
Sacks.
Obstacle
to
recycling
-,,,,-----A---->..
;
5
-.e
- Hotels and Restaurants
_ ;
These are often disappointing,sources.
r ,[email protected]
Bottles
Film
The main wastes
and jerrycans
Food containers
,
.
- LDPE,>HDPE, PVC, PET.
'\..‘,
- HDPE, LDPE, 'PS, ABS.
are
'
me
a
sacks and bags - LDPE, HDPE, PVC!.
Drinking
straws
- LDPE, HDPE, PP or PS.
*
'..
.
Drinking
tumblers I- PS.
I
0
I
,
Factories
and warehouses
I
These may be extreme 'y-fruitful.
Never let anyone at the -source
of supply know what / is done with,their
waste or they may try to
The range of wastes '
recycle
it themselves
or charge you for it.
can be very large but some principal
ones are:._ I
7
I
Process scrap from manufacturing
operations
that
plastics(in small quantities
that are not worth
trouble
to recycle).
May be any polymer
but
manufacturer
usually
knows which.
use
the
the
Damaged crates
(bottle
usually
HDPE or PP.
_.
.
'.
a
Damaged. or undamaged
bottles;
barrels,
etc.,
usually
HDPE, LDPE, PP, PVC. There is
often
a good market
for
reuse iof
secondhand
containers,
katch
out for
'
so prices
may be high;
poisons,
acids and other nasty contents:
..a-, :
r "
Overwrap film - Many goods arrive
at the factory
over
,)
wrapped with
polythene
film
to protect
them.,
For
L
example bricks
may be transported,
loose on, a pallet'
with shrink
cover.
Small items are often mounted on,
11
a card then overwrapped
with film wh ch is, shrunk on
to ma
ateridl
may
be
'I
_I
I
firm
package.
Such
-4f"
excellent
for recycling:
thic L-f-J
, ree fro? impurit$es.
.
.
4
and of large quantity.
PVC is sometimes used.
Polyurethane
foam or expanded polystyrene
padding -'
do not collect
unless an economic,' profitable
market
has been identified.
I-.
‘.
Rope or string
- if it looks like plastic
it
PP.
Nylon rope does not hook like plastic',
where the end‘:may have .been melted)'.
I
will
be
(except
.
Damaged
clothing
or undamaged
etc.
bowl 9,
'-
buckets,
‘
protective
'
Shops and Supermarkets
,.
Shrink wrap film - this may occur in huge quantities
if it is used for packing
cans and bottled
goods -c
LDPB or PVC.
Beer and beverage'"::can
skeleton
1 HDPE, LDPE.
Hospitals
and clinics
holders
-
the
"Six
pack"
P-
,.
Hospital
wastes must be approached
with care as they may contain
However in many countries
the
dange'rous or unhygenic
materials.
dangerous
wastes are collected
separately
for burning,
so the
remainder
are typical
,of any large residential
institution'
(3ee
Homes) with the addition.of:&
, . . . . . . . .
'
T
In addition
to the plastic
this
carries
X-ray film.
silver
bearing
emulsion
whose
value
justifies,
reclamation.
(See Work from Waste).
The
separate
plastic
that remains is usually
PET but was formerly
cellulose
acetate.
There may be an extra coating
of
other polymer.
+-
'
Autoclavable
holloware
- many items
formerly
of
stainless
s'teel,
such as ,dishes,
mugs, buckets,
urine
made
of
bottles,
bedpans
etc.
are 'nowadays
In
the
hospital
procedure
they
are
polyp+ropylene.
sterilized
before
reuse by washing
and autoclaving
(heating
to high
temperatures
in a steam vessel).
They may be collected
for recycling
(and PP fetch'ea a
higher
price
than many polymers)
PROVIDED they are
put through the washingand
ateriiization
process for
the last ‘time,
before
collection
by the recydler.
Hospitals
may caloulate'
that the cost of this,
leas
the scrap value will
be no greater
than the coat of
safe disposal
by other means.
It is stressed
that a
without
who
items
recycler
collect3
such
sterilization
exposes his employees andfithe public
to
grave risk of disease.
Streets,
parka,
‘beaches
etc.
,
c, *
*
'.
.
.
Waste in such places
is litter.
How much and what kind will
depend on the habita,of
the community and the municipal
cleaning
services.
It will
usually
be dirtier
than other wastes,
having
collected
sand, soil and dust while lying,
but these may be easy
to remove.
Collectors
may p;efer
to avoid these materials
or to
-wear gloves.
Litter
that, has lain
some time may have been
degraded by the effects
of sunlight.
This is mainly
a surface
-
s
4
. _,
-35-
,.
;
.
the product
from being
effect
and does not prevent
for the sorter
Where it goes deeper it may be necessary
brittle,
part :and throw it away.
off the affected,
recycled.
to break
\
and schemes
,'
To collect
from the above soarces needs transport
to and from the
location
where the,waste
arises
and this ,,is costly
in time and
Some communi,ties
will
bring
their
soiled
wastes
to a
money.
such as a "skip"
located
in the car park of a
central
.place,
Often
they will
wash them beforehand,
a double
supermarket.
Such schemes have been- fully
-dealt./with
in "Work from
benefit.
Waste".,
with the problem of tibtaining
sufficient
For plastics,
they can
weight‘ of material
at acceptable
cost and cleanliness,
be good if correctly
operated.
*
Refuse dumps and transfer
stations
Special
%
collection
centres
can usually
,be found at the'
Great quantities
of scrap plastic
It
is
not intended
to
refuse dump or garbage transfer
station.
discuss here the merits
of refuse separation
schemes, nor whether
the co-llection
o$ materials
from such
one should
encourage
These should be municipal
decisions.
In
unhygenic
locations.
developing
countries
the public
may not support,
collecti.on
centres
but municipal
dustmen often
earn extra, income by sepArmies of
arating
recyclables‘during
their
collection
rounds.
either
in the streets
or from t%epoor peop'le live by gcavenging,
refuse dump, and purchase from them may be the cheapest source of
They may be prepared
to wash it for a small
plastic
waste.
but a second,
careful
wash will
still
be
in price,
increase
0
," 'r-r
necessary.
It may be satisfactory
for one scavenger
to ,ait as middle' man
The price per
with the help of a small cash float
to start
ulj.
unit
of weight
(lb or kg) that he will
pay his fellows
must be
agfeed by tall
and he receives
a small
extra 1 sum (which
may
increase
by steps with increase
in the volume of'material,
he is I
Such material
may be purchased
on a "weight
able to obtain).'
produced"
basis;
collectors
may work leas hard if paid by time.
,
'
a
.
.
t
%
.
METHODSOF COLLECTION
3
.These have -been fully
In general:
“>
\’
,
.
-
discussed'in‘"Work
from Waste".'
*
.
%
House-to-house
cheapest with
8)
."
b)
ji
collection
a handcart.
.l
near
the 'processing
depot
is
.
_
House-to-house
collection
far from the processing
depot may
ii
need a vehicle
or animal drawn caft. .
_)
Collectors
work from it,,
carrying
'sacks and return
to it
when the sack is full.
.
Moulded or extruded
plastic
goods are very light
for their
Any contaigey,
,' ('&-,,m .-...._.__ .,,,
contain.more
air than plastic:
volume,
have its volume
sack, a cart or the back of a lorry),;will
used up before ite weight
limit
i&reached,
,which makes the
As the material
is sold
cost.per
unit of weight very high.
It.. f.s...ae!F.&sarg. to -.'.. -' -. .- ( ...!__.....-this becomes unprofitable.
' by weight,
to use the fdll
weight capacity
of
"densify"
the material,
the container
at all times.
This can be done by hand, with
a chopper
or other
implement
carried
on the collection
in sorting
However, this may lead to difficulty
. rorunii.
I
see page 46.
_~
0.
c)
-.-
Travel
by bus or minibus
is practical
for coliectois
carryand tough).
ing two or more sacks,
(which must be large
They should
chop up large
pieces
an& aim to collect
not
less'than
40'lbs
(20 kg) per day per collector.
Collection
from the .refqe..
concentrated
sources should
time, by high-sided
lorry.
will
hold greater
weight.
d)
other..
dump., from,..f&tories~or.
be not less %han one tonne at a
A lorry
fitted
with'a
mesh cage
8
. ,_,..:.
s
I
' ECONOMICS OF COLLECTION
**
s
To:
Profits
to be made by recycling
plast-its
are rarely
large.ensure that [email protected] earn sufficient
for their-needs,
COST of allactivities
(startling
with collection)
must b% carefully'checked,
Methods used Jo calculate
and compared with the value of sales.
costs have been carefully
explained
in "Work from Wastell, Chapter
..n
18.
*
Yield
.I
_I
-
.__.-. --
.
;--
,.,.
l
-.
~_ -4
,.,.,._. I"..I.y -....,..,
.II
'
:
.~
.
2
,
.pr
Because selling
prices
are per tonne (or per kg or per lb)‘ all
However. the $eight
to the, same basis.
.~_ ~~-co9 ts are *converted
than
that
collected
because
some
delivered
wit11 be smaller
material
is discarded
in; the .sorti-ng--I.~~ocess...
The. processing
t.
J
I.
"yeild"
'is equal to
.,l,,,
,,.,,.,
_,j
_(,_,
1,1
_,,_,
I, -,l-lllk11-1,-1~,y,-'-'-,\,
I,,. : ,,
s<
. ..
Weight .of material
delivered
'to customer
.‘,
.
Weight cQllected
to yield
this quantity
.
a
*
Costs should be -expressed as "per.tonne
delivered". --L-. Where costs
~ -are for tonnes collected,
they need to be divided
by the yield.
//
I
.fo-r-:... i ....-I-___*,I_-.....:;
The ..' a
h
".. ... .. ... ,,
.
..,,
_
j These .may be calculated
on-a daily;--weekly
or monthly basis,
each collector
individually
or for the whole team
.~...._ t0gethe.r'.
-.- -..- ..-. following
should be included : ./"-. -..-----.---.!.. ..
i
Ij
Cost of labour (wages)
~ i
__..... .-----
* Labour overheads
supervision,~-etc.2.~
d
'(clothing,
~..~
.
Transport'
f-bus fares;
Publicity
etc.)
-(advertising,,;
%suran&e,
lorry
pension,
fuel,
leaflet.
5
prin-fing.
c
distribution
.
Dgpreciition
of equipmen< (cart,
lorry,
etc.)
.d ~--.. .iL---.
- .~_ ~_ z ---. ~.>-':x..T=-.
L.
Interest
on loans to buy equ'ipment.
1
...
*
’
:
a-&
Collectibn.cost
tonne delivered
L
_~_
~.,
_-~--
I
/
-:
:-
.' -
;
~-cost
x Ylteld- .--- - - .- -^ ---. I
c
_. ’
--1
.-a-
_‘,
1..
1
.
*
..
,
‘:
-.
.
*
.>
>
\
.
..-,.-‘-
0
-.
~-.P
t
I
a.
., A-
i
t
-~ . s
~~.
= ~Totai,co%Iection
---~46a-i-ghtico-~le~ted
per
1 ~_
~~~~.__
. . a.4
a
a
_
,,
,-
,;,,.,,
.,
.,
,<
.,
.,
,,
,.,
,,.,
,.
,,.,,.,,.,,
,,.,,.
,,,.,..,
,,- ->“,-,‘i,“,‘,;
,y/,.,,
/ .,..,
-,~-,Y,
,r,rlr,r,L,_l”,l,~lr,“~-~-~”
0
7.
..”
4
*
1
.
n
I 1
..
”
_(
a,
_.,.___..
_...
3
v-
,.-
....--
-__ __L
..
5
1 -~ --------
:
--~-
..!?E
”
--....
_.-..
*I ( ___ .__._- -.A - ...__ WL.
‘.
1
‘?
I’
~_~.
~~~
,
,
‘
,
,
,
,
.
:.
PROCESSIRG ,-:
:*\
-:
_ ----- .,
.
,. ,..,-,-..
,.,. ,..,
~._.
.._..
..~
__._
-. --- -This
chapter
discusses'
processing
scrap
plastic
to obtain
a
granulate,
crumb or pellet
suitable
for moulding
or extrusion
processes
(which are explained
later).
The following
operations
are involved.
The
order
must
be
decided
locally_;
-'-.- -~
~ ~ ~~ ~~
/If cleaning
be cleaned.
._~ _..~
If sorting
unplea3ant
sortkng:
Size
.,
.
(T-~&.g
is done first,
c
is done first
for thesorters.
.
_._
-.
Tm
_I
Bagging
_.
Cleaning
unwanted
material
.,,’
-.
Brushing
I.
I
pashing
.- ._---5
--~
,
.
-
-~ Y-2~~~ -*
-
- ----
~~~..~~-~.
.* .-.._1 - --.
._ _ _______..
-...-.---
and
.-. --Delive_ry_.
~~ _
-
.~~~
.
-.
-.
with
are 1ist.e.d ,. in,,,order
o.f=..&eaning
the results
are good enough.
a soft'brush
to remove dry sand,
in plain
cold water,..with
a brush
ti
Washing in water with detergent.
Powder
cheaper than liquids.
The cheapest way is
few drops of liquid
in each scrap- detergent
add more if necessary.
.---
~~, --.--
,
grit
a
__..~
__
_---_
'.
"'
~~~- --A.
/ -~
__-~
.------
~.~_~ .- ~~~
‘c
etc.
detergents
are
to use the last
bottle
and only
-:
---~-
-.rYF.-m=-.+=Z
power:........-.:......:..,.f’~::,[
a
--
Washing
in hot caustic
soda solution.
This
should
be
avoided if &ssible
but may be necessary. to remove 'oil or .'
grease or heavy dirti
It-is
essential-that
sto
length,
rubber gloves,. free from . holes are worn.
from ~si.ippliera'~of~
prote&ive
industrial
clothing.
Those
sold by supermarkets
or. hardware stores
are rarely
strong
or long enough.
Caustic
soda can normally,be
bought in a
1
:
)I
hardware store.
.
!' :,
~.
.,
-.
3
2
.,
may
-1
it-may---be~unneeessarily
.
The following
methods
work down the list.until
~ I?,.
,--,-.:. ;”
., .,
~~-.
~ ~--~-
,
~~~~-~
~!&ater%al--de?ivered-e-the
~3uFiZ%mer~$~.b_e
_fr~..~fro~..d~rt-.-80---.~----c-i-_
-.___.
_
-..-.-__
.____..__. __-_.---"'.'--; ..-.. -- -.. -- 7-i- -.
every piece should be cleaned but to achieve maximum.production
from a given number of workers
keep
washing
(Fig.
12) <to
the
.
minimum.
P
4
._T
., .,
-.
Pelletization
d)
1.
reduction
Granulation
b)
.,
-
CHAPTER 5:
--
Cleaning:
,
~~
._... ._,.-.-.-.. -- -.
~
~...
--A--
-L-
*
i
h
/
----_
_..__
-..
.-I..
I ___.
.*
,,__
FIG’JRE 12 :
-
c
For all
types-X
brush is useful.
at a comfortable
cleaned quickly
e)
- - --L
.
--
wasning a mop, cJot& .or ny~Br~tl.ed
Cleaning
baths‘or
tanks ,should be placed
Throw away"objects
that can?& be
height.
and cheaply.
___~
._,..__11_
Cut off ‘impurities
that
cannot
be removed by washing, I
of -metal
or.
rings
plastic
and paper labels,
r especially
It is easier
to.
abound bottle
necks etc.
ot$er plastics
-crr+*~~fA~
a :,&k .rsmdtt---a label'is
removed are
amounts of glue that remain after
usually
acceptable)
~ .
I.
To save time (that means cost) and waterdonot
rinse.after
Place objects
.to drainion:
a
washing unless
unavoidable.
taking
care that no sand .or\ dust
sheet of polythene
film,
can blow onto them. 'When dry, store in a drum or carton.
Testing
for Different
_-
i
Polymers
&
p,,
Although
attempts
have been made t/o develop
automatic,,
none
has
so
far
I
plasticscrap,
ways or sorting
mechanical
succeeded commercially;
the only sure method,is
.by eye and hand.
As many different
polymers look identical,
considerable
skill
is
This is gained by practice
and by
needed to tell
the difference.,
a..
Even testing
is not easy but the
testing
when doubt exists.
">
following
system works reasonably
in pr,actice,
.
_-~-_
,__
__
,._
_____._.,_
___..
"
_.__,__.
_
-.---..-.-------I...--.(__
_
_
-. - .._
--.-.
i
for diff;rent
polymers,
Yorkers
are trained
td,earry
out tests
'
and
build
up
experience
of what
' using locally
collected,material,
different
products
and different
brands of the same product
look
like.
After working for a few days in this way they will
be able
The .remainder
8.
to distinguish
90% of all polymers by appearance.
The rule is "If in doubt test.'
If still
.in doubt,
need testing.
4
throw it outW. '
The tests
explanation
a>
b)
are tabulated
in Table '3 but the follo?&g
further
is needed.
I*
\
PE that“'has
been
Finger
nail
scratch
and flexibility:
exposed
to the weather
may have hardened
and
'Very
thin
mat
rigid
and brittle.
unscratchable,
any polymer may Beem flexible;
very thick
of any
rigid.
II
(Fig.
13) This is---very useful\ to.
Flotation
test:
between
high..,.d.en~si.ty ..pol
difficult
distinction
(~especially
iI! ittlias~6ee.n
hard&id
by exposure to
Also
between high
and.' low density
and polypropylene.
polyethylene.
A mixture
of water and alcohol
isinade
up of
'exact density,
80 that one material
will
sink and the other
float:
L
!
f
?l
-41-
:,
.
.
'
_.
~_____.
-.
../
1
FIGURE 14:
:
Testmg
by; burning.
%
.I
9
,’
.:
_
1
-!
‘.
.
i
Cutting
scrap
on a circ
1
.I
,’
,
i
:
P
\
.
L
i
If pure alcohol
(ethyl
alcohol
- density
available
use iso-propyl
alcohol
(also
Mix
about 0.78).
Propan-2-OL
- density
(range
0.9 to
and use a "hydrometer"
A density
of
.density
of the mixture;:
that
poly-propylene
floats
and HDPE
A density
of
density
PE) irill
sink.
distinguish
HDPE from LDPE.'
about C.79) is not
called
Propanol
or
the two thoroughly
1.0)
to test
the
0.925 will
ensure
(or
even a medium
0.93 is better
to
_‘
I
.
I
1
* /
I
1
,:I
Flotation
tests
between polypropylene
and LDPE cannot be
done wit.h certainty
because ,their
densities
can overlap.
Use the fingernail
test and visual
appearance instead.'
Q
/
Once made up the mixture%
can be kept,
p>rovided they are
/'
securely
capped to a.void evaporation
.or checked
with
a 1
Flotation
may be affected
by
hydrometer
before
use.
avoid
by adding
a couple
of drops
of 1
surface
tepsion;
'washing
up liquid
to the water or mixture,
or by carefully
pushing the sample under the surface
and swirling
gently
to
remove any air bubbles.
a
I
c) ..
(Fig.
14) cut a sliver.5cm
long and lcml
For.the
flame test,
to a poiht at the other end whicq
wide at one end, tapering
Hold over a sink or stone,
away from the body and
is lit.
The drips will
only burn as
clothing
as samples.may
drip.
I
they falleif
they drop from within
the flame..
I.
d)
.-
.,. .,
e)
.
’
/
PVC can be confirmed
by touching
the object
with a red h{t
copper wire and returning
the wire to the flame when St
Burn off all residue
qf mate,rial
before
;
will
burn green.
(Other .polymers
repeating
the test
with
theTame
wire.
that
contain
chlorine
or fluorine,
such as PTFE orholyvinlyidene-chloride,
also give a green flame in this
test
.
but they are rare).
L
_,_. .
. . . ; ( ., .
Thermosets
can be tested'with
:a 'piece ofiwire'
.just
,If the wire penetrates
it is a thermoplastic,
red heat.
I
.not it is a thermoset.
beloti
i?
I
*
C’\_
.
_,
.
. .
w
e
,
- *
.
r;
Readers
referred
,..
requiring
'more complete
to Ref.'16
and'l7.
.
,. /
tests
to
identify
plastics'
_I
are
I
TESTS TOiDISTINGUISH
TABLE 4
1,; Smell on
I-Relative
-\ Burning
Ii/ Burning.
1 'Density
I
I
I
\I
I
,
Polymer-~
.-{
Flexi, bility
I
I
1.: In-1 Water
I
I
I
I
I
I
? I
/
o
---------------------------------r-----------------------------~----------------------------------------------------------Lou Density.
1 Very
1 Floats
1 0.91-0.92
1 Blue flame
I'\ Like
I
(a with yellow
Polyethylene
/flexible!
Icw=
I
II
LDPE
1
tip:melts
and
1'
I
I
\
drips
burning
1
/
I
j
\
i
>
I
droplets
;I
I
3
I
I
I
1
I
I
I
I
POLYMERS
1
1' Scratches
1
\ with finger
I
nail
1 0 1
I
I
f
I
candle
I
I
IS
I
I
1 Yes with
1 'difficulty,
I especially
1 when cold
1 weathered
; No
/
i
1
I
I
-------------------------------------L-------------------------------------------------------~-----------------------High Density
ditto
Much
1 0.96
ditto
I Floats
I
Polyethylene
less
1
I
3
HDPE
flexible;
I
I
than
(
I
LDPE
1
I
Y
I
Film
1
I
I
crackles;
I
I
I
I
when
I
I
I
i.
1
bent
4
Iu
I
I
I
1
P?
I
b
I
II
/bend bptl
idoes not\
1 break
]
I
1 when
I
! bent
1
1
I
1I
1I
1
I
1
1
I
flame
with blue
base.
Can
drip burning
droplets.
1 Ditto
I less
1
1
I
I.
I
I
feel
Iexist
Very tough,,
Hard to
tear
;
,1:
1
.,:)r.
1
.;‘
*
,,_,,,,__,,---~--,,,---,-,,,,,n,
T\
; No
j
I
.-
8 .
I
I
I
I
but
strong
'
.
.
I
1
I
I
J’ I
I.
-----------------------------------------------------------------------------------------Polypropylene
IHard to 1 Floats; 1 0.90-0.91
1. Yellow
or
Notes
\Has a na;y
1 No
I
I
I
I
I
I
1 Yes
/ Easily
I
I
I
b
+.
I
Can it bej
perfectly!
transj
parent.
1
I
-
i-X 1 No
I:
!
1
I
I
I'
I
/
i
IVery strong
IForms an
'Ialmost
Iunbreakable
" \.hinge if
I-folded
------------------------------i-------------------------------------------------------------------------------------------
Polyvinyl
Chloride
PVC
Rigid
PVC is
brittle
Plasticized
PVC can
i.-tje ~VSl's
I
I flexible!
i
--e---T--m-E--ma-
1 1.2~i.6
/ Sinks
11
I_
!
1
1
I
,'
,I
I _
I
I
I
I
I
-. i
1
1
1
/
'1
I
1
I
Yellow,
sooty
smoke; does
not continue
to burn if
removed from
flame.
,. .(.,,_,__
_ ,_(
I
I
I
I
I
I
---“T-‘----“‘-----------------------------------~:~-----------------*--------~-----~
I
1
1
1
\
j
Rigid PVC No I
Flexible,
'
plasticised
PV; - Yes
I
,
,.,..I..,.,
.,.._..,.
.,_.~
._._.... ._,_,_,_,_..l..~
“I‘
I
I
Pungent
h;r'drochloric
acid.
DANGER
do not inhale
.:
( Ye.s
I
I
1;
1 //
i
1
Touch with a
red hot copper
wire 'and hold
wire to flame.
i Green flame
‘1 indicates
I PVC or other.
polymer
i containing
I chlorine.
--4 ___-- i, ---- ---mmd
1:
.,
..
,
Polystyrene
P-s
[ Very
- !~Rigid'
; and
ibrittle
1 Sinks
,
1
I
I
! _
,-,,,,-----------------------------------~----------------~-~------------------~-----
Acrylotnitrile/
Less
Butadiene
I rigid
Styrene
ithan PS
'ABS
I
--------_______-____----------I
Celulose
I
I
Acetate
I
Ch
I
I 1.0-I
I
I
I
I
1
c
Polymethyl
Methacrylate
(Perspex,
hc6yld.c)
Pmu
7
,I_
Sinks
I
I
I
I
.I
I
I
I
I
i
I
I
I
I
.:
1 Sinks
I
I
I
I
I
I
I
I
I
; 1.1
I
I
I
I
I
I
I
I
I
I
I
I
I
1 Sinks
I 1.4
I '.
I
I
I
I
I
Q I-*
I
I.Often has s.i,lky',
lgurface
fir&h
0
I!No metalic
Ging
”
*
j.
lwhen dropped" " 1
--w-M-------es __--_---_------l
I
.
/Weak
*
j
I Yesi
I,
I
-1
* 11. . I
I
1
’
\
1 Does not .drip
1
1
1
1
1
.\
.I
I
I
Blue flame.
Melts .& drips
Does not
continue ‘to
burn if
removed from
flame.
I
.+
1
I
'
lI
Strong yellow
flame with a
little
black
smoke.
I ‘A
*
I
I
I
I
1
I'
I
i Sinks
i
I
I
I
Thermosets
I
\
I
I
I
I
I
I
I
I 12
'S
I
I
-w
I
I??
‘~,,__,1----~----------,~------------
0
*
-
I
I
. . I
‘/
cl
1
XI.
1
,Yes
!
? 1
1 No-unless
1 very thin
‘I \
(
\
v
I
,_..
\-‘------&---
ITough and
1flexible.
IShiny surface
1Crystal,,dlear
’
T
' P
I
7 i
I
i Sweet
,
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
J
.i
/ .
/
I
.
I
’
I
/’
..
‘i
.
*
.
-“i------------------------------..
i V-7
Tough
3.
w
\
_---------------------------------’-----~--------------------------~--------------------~
Polycarbonate
'PC
I
_. <. II i ::’
,
I
.
I
.-
",I
_----------
-e-e--
. !Very tough
'land flexible
.INo
I
9
I
------:‘-‘-“--’
'1 Ng
I -'r
-
,
I
c
1
I
i$tqong but.)'
lbrittle
butlwill
Ibreak if,bent.
IDoes not ring _
0
-
.
-----i--d--
--e--m
I
81
j Little-sdell
, butter.
1
I(
---------------
I
I
L
\ ,Yes
I
-m-e--
%I.L\ike- burning
1 hAi';- .._,
\,
I
.
/ . i
'
.
I
I
‘I
I
I
I
___-_________--____-----------
---_---____--_______--------------------
1 Very
IFlexible!
0
b
1 No -
m-e---
I
m
---------‘--‘f”“’
,1
1 Fruity,
sweet 1 No1 Yellow flame
1 like, flowers
I
1 with blue
4 *I1
1 bas'e. No smoke;
I
____________________-----------------------------
I Very
\Flexiblel
3
4---_-----------
I
I
------______________------------
I
I
I
I
I
I
I
I
Polyethylene
Terephthalate
I
I
) 1.0-1.1,
1 1.2
IMakes
\metalic,ring
-Iwhen dropped
Ich a hard surface
1 Yes
1 No
,'/ Burns stronglgj,Sweet
i ,,x with yellow
I
/I 1 sooty flame.
I
; I
: 1 Leaves no ash I
----------------------““--“---‘------------~--~--
[ 'Brittle!
_j
Nylon
N
.l
1 No
, 1 Rubbery
1 Ditty
but
I
:-'lea+ks
some
1
I
I a
I
I
1 ash.
I
. :!
I
i
I
I .
I
+
I
I
‘.
’
__--__--___----------------,,--i---------------------^----1 I;5
/
-i Woody
. ' -j.No*
i Like paper,
1 Sinks
I
I
1 not if flame
I
I
0
I
,i
I
*
.
_
1 is removed
I
I
I
I Sinks
-1
1
-------_____________-------------------
1
‘
n
aI
I
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.
I.
'
\Can be bent jwith
,pli%rs)
without
Ibreaking
I
IHot wire
will
not
, ‘IIpenetrate
,
4
.
Sorting
zorting
is easier
if objects
have not 'been chopped up as this
Organise
sorters
so that the
destroys
the familiar
appearance.
and the best sorters
sort'each'
least
skilful
sort into
colours,
colour
into different
polymers.
In household
waste there tiill
be little
materia,l
'other than PVC,
These can be,accurately
sorted while all
H,DPE, LDPE, PS and'ABS.
container
for
are thrown
into
an additionalother.
polymers
an adequate
quantity~
has been
further
so.rting
later,yhen
collected.
* ,
Sort into labelled.
conta?ners.
Use the largest
containe&rs
for
-
and orange
.
black and green
.
.
'
v_
7.
Blue
.
I$
1
.
1
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. I'
.
'
,
I,)
.. .
,
> .-
0 -.
,
,
.
'.
-ii
T = *'
=
* -
.' .
I a
*
. ..
',
,
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'
R'.'
transportatio
volume.
7.
Size reduction
during
coSlecting
reduces
Size .reduction
at‘ t Pe depot =
but may make sorting
difficult.
,helps transportation
to the customer and .feeding. of material
to
i'
-.
the granulator.
..I
I
\
The easiest
method, is w%th'g'circular
saw,. such as is used in a 1
for
cu,tting
plastics,
are :* q
woodwork
shop - special
blades
~
available.'
Saws are difficult
to guard and can.take
a finger
off
just as'qui'ckly
as they can cut through a.lump of glastic.
51
.
Size
reduction
h
I'
‘ ,*
--_ -
Red,'yellow
Brown,
..
Heaps on the floor ,get mixed.up.
the large volume materials.
Establish
a ,foolproof
system
of quality
control.
- The best
checks every container
when full;
If
or the supervisor,
sorter,
the
whole
container
should
'even one wrongly sorted item is found,
.
.be emptied out and resorted.
il
<>
8'
"
Place twenty 'different
examples of
It is easy to test‘sorters:~
number
,tliem
and
'ask
the sorters
-broken polymer around the room,
19 out of
who can correctly
identify
to list
them. I Only sortprs
_ .~, Y..
. .
1 .
20
'ghould
be
employed.
'I
B :I
.-- . ..
s_-.
.
;ic-'Sk
colour
asa&eed,with
In. addition
to-sorting
by polymer, .sort'by
Not
all
colours
need
be
sorted;
perhaps
five
the customer.
'
,9 .,
such as:'- '
groups will
be sufficient
L
Clear
,
.
should have hair
Operators
should be trained,
clothing
such as scarves or sleeves-tucked
in.
worn to protect
the eyes.
in
6hey should vwork.where they cannot be disturbed
or'interrupt:ed
by,!
This means working
in isolation
and is unpopular'
other workers.
Frequent
breaks for a chat and relax!:,
but essential
for safety.
conce tration.
.C
ation will
help the operator
maintain
\
f7
The object
to be cut should be held in both hands Which pass,
either
side of the blade (Figm.
Feeding sh&ld
de
well clear,
to force
the object
through
the
with
a firm
steady
pressure;
and the hands being drawn into
blade may result
in "snatching"
the blade.
Thick leather‘gloves
offer
protection
but'may
not be
acceptable
in hot climates.
e
The saw operator
should know exactly
how small
Cutting
too small is costly
and unnecessary.
be.
A
.
a cap and 1,oose
Goggles should be
objects
9U
.
,"
...
nee,d to
If a saw is ‘not available
a hatch,et
and a solid
tree trunk
or
, block may be used., -The object
should not be held Chile striking.'
The hatchet
swing should be ,from above the head in.'the
direction
exactly
between the widely
spaced legs so that'a
small deflection
of the hatchet
when it hits
the object
will
not result,in
injury
to the legs.
Safe'ty spectacles
'should‘ be worn to prote-ct
the
eyes from fragments.
J"
.
*
:. A handsaw, with the object held in a bench vic,e can also be used.
-
The size for material
which is to be sold without,
being granuNo rules can
lated>must
be judged against
the cost of transport.
if obje,c'ts 'are made flat
'the
be laid
down except
to say that,
best densificdtion
has .been achieved;
further
size reduction
will
not yield
the same benefit.
-*
_1,
+
,
'
Preparation
.
'
,
D
7
'.L
"'
.
.
for
Moulding
.Before scrap can'be",ied
-izto an, injection
.moulder or extruder
it
must be- conver tl ed into
a' "homogeneousn,
free
flowing
grain,
* powder, pellet,or
crumb.. There are three ways of achieving
this,
J .
, depending on the cost and quality
requiged:
*.
+.,
--
~,
, I
Granulation:
This
chops
irregular
shaped pieces.
-solid
material
0Y
'
into
'regular
'
.. '
If
,
sized,
-.
Crumbing:
After being, chopped into flakes
thin film is.converted
7into .a heavy crumb,
dense enough to"feed
'into
!a moulding
or
extrusion
machine.
This, is sometimes called
"aggldmeration".
Y
1
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.
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-
.:
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r
Pelletizing:
Granulate
or
crumb is. melted,
dirt,
and made into pellets
of a given size.
i
These fm&rtant
operations
will
be described
.~
-----_
screened
to
remove
*,.
.
--.
in detail.
II
-1
GRAN&TION
This is performed
by a simphe machine called
a granulator.
One
type comprises
a rotating
cutter
mounted on a horizontal
axle
*
(no,t unlike
the cutting
cylinder
of a grass mower, but with
straight,
not spiral,
blades),
which- chops the material
against
stationary
blades.
(Figs
16 and 17).
Usually
there are..,,
fixed,
three or four rotating
blades and two fixed blades although
other‘
comb&nations
are used.
The blades
are replaceable
and can be
reground..
The rotating,blades
are bolted
strongly
to a solid
rotor
shaft,
with
a bearing
at'. either
end and a pulley,
belt-driven
from an electric
motor.
The. fixed blades are bolted
to the cutting
chamber and have adjusting
screws at either
end,
to move them in *or out until
the rotating
blades just
fail
to
touch them.
Good quality
blade steel. is important.
Another
kind of granulator
has a vertical
axis with
rotating
in a cutting
chamber shaped like
an upright
flat
circular
base of the drum is drilled
with holes
grid.
The drive pulley
is below the grid.
See Figs.
This type is less, efficient
than the horizontal
axis
much cheaper to make.
_.
6
flat
blades
drum.
The
to form the
18 and 19.
machine but
Material
enters
through
a hopper-, 'a steel
box'-mounted
above the
cutting
chamber.
For safety,
modern hopper design,makes
it
) ,impossible
to touch the blades while
the hopper is in position.
The hopper is usually
hinged
to allow
access to the blades for
cleaning
and resetting
but a device should be fitted,
to prevent
the blades
turningc'when
the hopper is open.
It, is extremely
dangerous
to interfere
with this device or have the hopper open
when the blades
are turning.
The hopper mouth is sometimes
fitted
with a rubber'curtain
to prevent
fragments
'spi 4 ting'
back
at the operator.
.I
,
.
,
Beneath the blades is the grid,
a strong. steel
mesh of regular
holes,
often
curved
to fit
the rotary
blades.
The hole" size
determines
the size of the granulate.
Small enough material
can
fall
through,
too large
material
stays
in the path of the i
rotating
cutters
until
cut smaller;.
A grid * _~_---.
size of 6mm to .$nm
(l/4"
to Y/8") 'is common, but this
should, be agreed‘ with the
customer.
Granulating
costs increase
for smaller
hole sizes;
if
the customer is usingdarge
moulding
machines he may be content
to have a larger
size of granulate.3
.
.
D
.
vr
I
A bin beneath the grid catches&he
fa'lli~-granu~&~-.,--Someti~letil~-~a mesh guard is-set
above the bin so that it is impossible
to'
poke a, finger
through
the grid
into
the" moving blades,
from
below.
*).
'
I
>
-.
~ -48-
* !.
c
----l
3
'A
fragments
'
Three
rotating
-
6'
\
bladed
-Strong
f ram&
ang e iron
-Perforated
gr
d
Y
‘Drive
belt
'
.
0
[email protected]
60
- co1 .ection
bin
.
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,
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FIGURE 16:
Granulator
.
:
\.
;
- (hor$zontal
.
axis).
L
-
.-.
.\-
FIGURE 17:.
.Granulator
‘1
- (horizontal
axis).
lectrfc
L
0.Y
motor
Hotating
* knife
Static
kriife
Perforated
grid
_C_
pulley
Strong
ariyle
iron
trame
\
Collection
bin
7
' &
FIGURE 18:
Granulator
~__
- (vertical-axi&)',pim
~~_~ I
-~
,,.
1 ~~.
- -----------t
0
*
P
,.
_r
,,.,‘,
-51-
. ,
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, , , , I,
I r
1,
-#
ii
a.p.1 ‘-lv,v...
:
.,,
.
1
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-.
are strongly
belts
and pulleys
that d-rive the rotor
The motor,
no .&article
of clothing,
mounted and should
be guarded
SO that
The motor needs a switch
fuse
can be caught in them.
hair etc.,
'All
granulators
shouid have'
"
and large motors'may
need'a starter;
I
stop button.
a large,
red, mushroom-shaped
I
machines
and in some countries,'
by law,
Granulators
are noisy
1
they must be sound proirfed
6-r~placed-iia-a'~souridIjroof~endl~sure;‘.
.Both are expensive
but employers
should be aware that prolonged
;
At +
can damage an operator's'
hearing.
exposure
to loud noise
least people working near such a machine should be given ear pro-,+_
tectors.
.~
_-~ ~~
~~-~
~~~ ~~ ~-~
Selection
of a granulator
An important
depend on:
decision
is
the
size
.
0
.
-,
This'will
required.
What kind
of plastics
and $roducts
are going
to be
granulated?
Tough polymers
like
nylon
or . .polyester
need..,..... .,.,...,.
. . _,.,_._....
pol~&~y-&~&
-.. -. mo.re. .p;ower. -than....po~.gs.ky~~~~...br.,_........
s-.--50.
What rate of pro'duction
is,required?
.
What size
of piece
is to':l;be
fed into
the machine?
The hopper mouth size decides-%h?s.
-2
2)
d
3)
-_.~____._ ~~--.
.,...........
_ -.~ ~.-
.'
o-
tlow continuously
wikl.it
operate?
For continuous
operation
a larger
motor is desirable.
For inter-mitten.t
operation
a
smaller motor .can be used as it has time to cool.
-'..___
',
For the activities
described
in this
book, 5 H.P. 4s an
i absolute
minimum.
A. 10 or even 15 H.P. granulator
should
'be obtained
if
possible.
Manufacturers
who can 'supply
information
are listed
in Appendix III.
1
.
*
Buyers in Third World countries
and U.S. manufacturers
are far
This is for thre.e reasons:
li
.
I
to buy the machine?
How much money is available
._.....
and power
Y...
-
Indian
machines
features.
Indian
I robust.
machines
are
will
find
pricesfrom European
higher
than those from India.
.
less-sound
less
expensively
manufacturing
0
.
”
.
._,,.
II
..
0
i
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t
Ik I
safety
finished,
but
no less,
.
(, 1 I !
, ,, .,y, _
I :,,
_I, ‘,‘,:.:
.: .,’
:‘““‘-
.
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0
and
costs are cheaper.
-2-_- A., '
, ' ~,_~~~__~ ----=-
.
.',
-
* 0
proofing
:
Indian
/
,
have
,.
y.
:
‘I
0
. _, ,,, ;..:\:’
.,
f
.-. .I .
. 'P!r~~. --- _l__
-e, ,
.,
‘y’::,:
.,,,
,,
,
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_
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&--.
_
I
\in the rough conditions
of the Third World, with
For operation
labour
less used to ope&?ing
and ma\ntaining
machines, ,Indian
machinery
from the
equipment
may be more suitable . than pricey
.__, . ...... ..
"North".
.
.._
D
2.
t
,
I
<When purchasing
.
a granulator,
1 or 2 spare sets
with fixing
bolts.
1 or 2 spare
sets
Alternative
customers.
include:
of
fixed
of drive
of
sizes
.
--
and rotating
belts,
grid-
blades,
motor bushes etc.
a
required
for
different-mm
if
‘machcine
it
details
of the
_
I-'X
frequency;
is 'it
a)
Mains
b) :.
Mai~~~~~oltag~,i.i,~.~it~l10
I
1
matter3
to check
?
is necessary
to
electrical
supply
50 or 60 cycres
.220
240
440
Any
.J
Other
.
-;(7-
~- -
.
,
When specifyingkthe
manufacturer
full
'This involves:-
,
complete
volts,
volts,
volts,
volts,
other?
single
three
siigle
three
per second?
phase?
phase?
piiase?-.
,
.
:-.'..I-
phase?
. '
‘1
.._..
._
- ...-Y-_ .. .._..._
_
_~_. .,-.. '.".
.,.I
I ranulator
when selecting
give
the
available.
are:
.I ,.I
t \
!.
.,.C-:- -.a_-
--.cJSI
.
l
Will
the machine be static
in&on"i
mobile?
-Does it need wheels?
"
Y
s
placeT
or
should
St
*
be
9
s
.,_,_,.,.,.
i-r,
,,.,.,.,.,.,.,.,.,1.?-1-*.,-,
, ,_,_,_)_).(_,_1.(_,_~.,.,.,...~.,.~...~-~.~.~~'~'~'~~~~~'
How easy
is.,.,.,..-..i.,.'"""
it to clean?. ..,.l.r.r.l.,-,.,.~-..~~~~~~~~~~~~
.,_,_,.
.
) se
0
i
What facilities
exist
for repairs
and, 'serv,icb
if it goes
_ ;
Does the manufacturer
have an agent
in .your
wrong.
'-3%
district
who will
give it expert service?
1
c
r'
* I
v
.
To order
machinery
from
overseas,
an import
licence
and
First
write
to
permi33i .on to send money'over3eas __~ "may be needed.
_
yeveral. manupacturers
for quotations'fbr
the macpine and spares.
c-.
"IThis
means
that
-~
Ask for "CIF" the cargo seaport nearest
to' you-.
,:,,i,
insuring
and transpordting
the goods to that
'
‘t&d cost of' packing:
*
You will, still
have to Day:
'port is pG.d bg'the
seller.
a
The cost
of cleeiring'them
Any custom3
~
An+The cost
machine
of
through
import duty
. *
_ - _____.
transport
a
,
,.
from
customs
1.
_the
at your
,...
home port
-
~
~-~
*
_ .-:.::___....
.- "
r
._ I
'port
to where
you want
the-.'
n'
The cost
of unloading
The cost
of installing
The cost
of electrical
it
from the lorry
d
it
-.>
connections
Allow for all
these when planning
purchase
of such a machine.
They may well come to 50 or 60% on top of the manufacturer's
catalogue
price.
..
-b.
'W
L
..-II-.,_.t .'".
Making your own granulator
‘1
,
I ,
,.*
It is neither
uncommon nor difficult
to make your own granulator,
if you are a competent mechanic.
In such a c&se the simplest
design may' be a vertical
axis machine as shown .(home-made)
in
\
Fig.19.
FI
_- _-.--FI GURE
19:
Home-made Gral nulator
(vertical
axis)
,_..---x.~--
Bag-s of flake
from granulated
film.
l
e
;I.*:
.\
I
.
.
I
1
.‘
advantages
of
a)
Far lower
capital
b)
No problem
your own.
with
cl
No problems
of importing.
The disadvantages
are:-
granulator
1
cost.
spares:
you .*will
always
be able
I
to
make,
,'
d*
-2-m
5
are:-
Home made machines are less
cost of electric
power will
This
b) '
Home made machiines
are
have such a long fife.
be so robust
Cl
Home made machi_nes are not likely
to be as safe:
if you
decide
that
it will
have. every
make your own machine,
your
health
determines
your
possible
safety
feature;
so
dangerous-money-saving
makes
poor
econability
to earn,
omics.
Time will
be spent
on. other things.
.I. .,.,.,. ., .,_,., .,
:
own
a)
d)
A
your
'making
The
making
.I
efficient.
be higher.
9
not likely
to
means &hat
the
!.
‘\5
'\
or
\
to
the machiSle which could be spent
,f
.,s,
./ ./...,~I.,.,.,,.,,,.,.,., ., ,, :, ,( ,, f., .,
The decision
whether
to make or buy. is a local
one; it will
or that of local
workshops
and the
depend on your own skill,
A good policy
for a
distance
and price of' commercial
machines.
group working
in a developing
country,
where such machines are
might be to home-make the first
.granulator,
a
not manufactured,
and use profits,
earned with it to
", small one with a 5 kW motor,
purchase a larger;more
power.ful,
imported,
'factory-mads&machine
at a later
date.
,@
A;
\
,:
>>,
ra o
'.
,''
Crumbers
‘
-I
20) is too light
and bulky to fesd'hto
an
F Granulated
film
(Fig.
\
It does not feed free1k.i.n
the
extruder
or injection
moulder.
L hopper .oc down the screw-.
It can .be converted
to freeflowing
'\\ material
This is like a
<n a machine called
a crumber (Fig.
21).
the
II vertical
axis granulator
but there
is no pe,rforated
grid;
material
stays
in' the -path of the rotating
knives
and; while
The volume of th,e
being chopped,
is heated to melting
point.
material
decreases a.nd, ,at the right
moment, water is admitted
to
the cutting
chamber. . The molten plastic
explodes
into
a hard,
dense, beady crumb, (F i g ure 22) irregular
in shape and size but
Large.
suitable.
for 'feedibg
down 'the barrel
of an extruder.
amounts of water vapour are produced and sucked out.by a fan.
/
,..
.f.1.1.1-,./
.,.,.,,,.,.,.,*,~,
',".1.'.'%
,.,,,.
r,
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..
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.
FIGURE 21 :
The Foliolux
Crumber.
'f
Starting
of film;
machines
from cold it takes abo~ut five minutes' to plastify
once the machine has warmed up.
half
this'
further
shred the crumb to improve its unaformity.
a load
Some
., .
Crumbers are not cheap;. the smallest
Italian
machine sells
at
about US$20,000 for an output of 60 to 70 kg per hour, but so far
no other method has been developed for such effective
reclamation
of film scrap.
The Foliolux
machine shown in Figure
21 is the
clhe apest available,
made by Plastmachines
of W. Germany.
,
One type of crumber incorporates
a washing plan&q&hat wiil'clean
To date3
soiled
wastes, but is extremely
expensive
snd complex.
no Indian
co-mpanies appe,ar to be producing
film crumbers.
Some
instead
use granulators
and add water in measured quantities
by
hand.
@
Like granulators,
crumbers can
introduce
water and a fan to
fit.
Vital
parts need to be
galvanizing
or paint.
Rubber
rotor shaft enters the cutting.
be home made; a pipe and valve to
exhaust
the vapour are simple to
suitably
treated
against
rust;
by
seals need to be fitted
where the
chamber.
,
Y
Drying
they absorb moisture
slowly,
and
Some polymers are “hygroscopic”
they can be successfully
extruded
and
need to be dried
before
Drying
can be done by blowing
warm air through
a
pelletized.
by stirring
in a shallow
trough in an
rotating
drum of material,
’
out on a clean polythene
sheet in the sun
oven, or by spreading
FIGURE 22:
Crumb - a hard,
beady material.
bryiong normally
dust and grit
are kept ozt.
the sun, provided
and
90 C but lower
requires
between 2 and 3 hours at between 70 C
time can be used’ for sun drying,
temperatures
and a longer
especially
if there is a slight
wfnd.
Polymers that particul,arly
need drying are nylons,
polycarbona-te,
ABS and high impact polystyrene
and cellulose
plastics.
.*
*
.
.
-/
.
.,
-
,
-w
,
.
I
‘,
EXTRUDER- PELLETIZERS
h
..
An,extruder
is a machine normally
used for producing
plastic
Lmaterial
in long,
continuous
rods,
sheets,
shaped sections
or
It can also. be used to produce pellets
and c.omprises
pipes.
(Figs 27 & 24).
,
A Fiopper into which crumb or granulate
may be fed.
-:
'1
able
to
contain
the
high
pressures
A strong steel barrel,
applied."
1
a>
ps
3,
'I . c>
.
‘_
_
i'
Electric
heaters and air or water cooling
pipes around the
barrel
to egable the temperature
of the material
entering
the nozzle to be precisely
adjusted.
’ d)
A nozzle?through
e)
rJ'hich the plastic
is forced
into:
containing
a hol'e whose profile
is
The die - a ' steel plate,
the desired cross section
of the-material
to be'extruded.
For pelletizing,
a "spaghetti"
die is used; it comprises
small circular.holes,
about 3mm diameter,'
arranged in one
.or two horizontal
lines
to extrude
tnultiple.
strands
of
or. fifty
on a
as many as forty
polymer simultaneously:
a' dozen on small machines.
powerful 'extruder;
“
. A system to clamp the die :to
the nozzl,e against.
the‘
pressure generated by the screw.
?
03
f)
d
h)
,, j) *
A'
/
,
_
down the
One or more screws,r designed to force the plastic
The design of the
barrel
and heat it at the same. time.
screw profiles
is critical
and they 'cannot be home-uiade for
this reason.
.
A motor and gearbox to drive the'screw.
4
This
A mesh screen .to strain
out non-plastic
impurities;
is fitted
between theabarrel
and the no zle and the-melt
isd
i
forced through it under high pressures,\sot f its design must
be robust.
The screen must be'. changed' when it becomes
,'
clogged with impuri,ties;
thi"s is.done
ia, one 'of two wags.
'.
A continuous
coil of screen on a reel at eitther end (like
a,
typewriter
ribbon)
passes through
a holding
frame and is
wound on (by an a,mount equal to the diameter.of
the barrel)
at-'intervals;
Alternatively
unit screens can be fitted
in
'
a double screen changer that can.be flipped
from side to a
* side (like
the- slide
holder
in an old fashioned
photographic
slide proj*ector).
This system,is
cheaper than the
Passage
continuous1 type but less effective
and takes time.
through a 's'creen, to ensure that there are no impurities
in
the reclaim,
"is the main purpose ,of extruding
and pelletizing plastic
waste granulate
or crumb.
.
I
*
a
I
r
k)
.
*
.,
P
I!’
1
p
l
A cooling
trough - info which the extruded’ strands drop as .
It is long. enough to ensure complete
they leave the die.
The strands leave it through a:
cooling.
/
’ /
r’
A pair of simple rollersor “tractors”
Haul off system.
whose” speed matches’ that of the extruder
feeds the strands
to the next
stage without
over-stretching
(leading
to -_ 4
breakage) or holding
back (leading
to tangling).
,I
Finally
the strands -feed into a rotating
chopper,
,,
Chopper.
a bin below.
short
pellets
and drop into
are cut into
Alternatively’
the chopper can be mounted on #the front face
requires
less power to chop, the, hot,
of the die, .which
is determined
by the
soft plastic.
’ The length of pellet
speed of extrusi,oa
and speed of the chopper.
1)
c
m)
.,> . .’ h<,’.,.*!,‘LI1:\,$
I’
\
1
’
%
(I
,
I
t
T
Selection
FIGURE ?4:
.
,Extrtider
of an E]xtruder
- pelletizer.
- Pelletizer
c ’
- 1
I
It may be worth-while
variations.
There are many, possible
consulting
your customer or another
producer
who is operating
plastics
machinery,
before committing
a large sum of money for an
The following
points need particular
extruder-p*elletiier
system.
attention.
”
/
’ :.
1
L
I.
b,
.
/
.
.
*
r60-
,
,’
0
4
_.
.
m
l
5
QQ’
a)
b)
c>
The output of the complete, line must match your intended
production
rate,
with
a margin
for
breakdowns,
screen
changes etc.
:
G . .
Each componehextruder,
take-off,
chopper,
must be
matched for speed. --.. .,,
'I
..
--._.
Motors and -other
electrical
iarts
must be rated' to the
see page 57.
electrical
supply available;
ii
"
'.
*
v .,
*
\
.
d)
I
The screw must ‘be suited'to
the polymer you are proposing
to handle and the form in which it will
be received
(e.g.
etc.)
The manufacturer
will
advise
on
crumb, granulat&
. .
this.
' Extruders
can be very complex machines but the complexity
lies in
the controls;
to achieve high output and good dontrol
of product
quality
every feature
may be electronically
controlled.
FOP
reclamation
extruders
this is not necessary.
P
i
1
It, is essential
.to see the machine
hembnstrated,
on the
application*
you have in mind.
A machine built
to,,,extrude,.PVC,
hose-pipe
may not be suitable
for pelletizing
high density
polyD
ethylene.
I(
Your order purchasing
,the machine should
'criteria
'that must be met by the machine
* payment is made. For example:I
.
'
lay down performance
before full
and final
,
"Shall
receive
polyethylene
waste granulpted
to a ,6mm mesh and
shall
extrude and chop into 7mm long pellets
of 7mm diameter
at
the rate of 100 kg per hour and continue
to operate under these
conditions
for a continuous
two-hour trial
without
interruption.:'.
+
\ 1
Bagging
i ' .'
.
Having
taken trouble
to produce
reclaim
of high quaIity
and
reliability
it is worth the cost of packing
in a professional
fashion.
This needs a small scale,
capable of weighing
at -least
20' and preferably
50 kilos.
Fill
every sack to ,the same" weight
and take care never to go under weight.
“45
*
/
,
i
IT
.
,
,
\
0
-61-
..
. v
\*I
.
e
‘r
r.
..’
1
1
rLt
.
\_
r
.
“i ~\
~~~_~~
.-_..:
,?
_’
‘j
b a,.
i
/f'.‘ $>
-i;T "'Is" ,":; a,
L.!\,Ia,
,>;; 'S
:'.
1.
. ' ..,': j \;
'r
\c'::.
':6::$'.$
a/.\I.
.‘# j. \p$
i '
:$
4.
Secondhand
sacks are suitable
~,for granulate‘
but pelle:tisad.,-;
material
justifies
a new sack or at least a neti-label
st&,@v.e%':
the o1.d one.
Label every bag with precise
details
*of-'..&6 conPrinted
self-'adhesive
labels
'.look professional
and
tents.
justify
a higher price than scribbling
with a felt pen.
The sack
ten be folded two or three times at, the top and stapled
firmly.
Use a rugged stapler
and strong wire staples \ or obtain
a heat
sealing
machine for polythene
(or polythene
coated paper) sacks.
This applies
pressure
and heat to weld the sack closed in a neat
\ 'straight
line
across the,top
and totally
prevents
entry of dirt
or moisture.
II
'l ~.
From time to timecheck
with your customer that the packaging is
satisfactory,
and that no bags have burst or split.
\
'
OPERATING,PROBLEMSTHAT MAY BE ENCOUNTEDDURING PROCESSING
.
DANGER!
In each of the following,
sw"itch off
disconnect
from electrical
supply before opening
ing or making adjustments.
;
the machine and
machine,- clean/
Circular
Machine
slowly
Y. -_
Saw
cuts
too
- Saw teeth
broken:
resharpen
or replace.
- Motor lacks power: ha
motor
i
%
serviced
or, if necessary,
>
I
Granulator
Motor overheats
cuts out
.or
- Saw clogged with
motor and blade.
plastic
cleaned
swarf:
- Cutting
chamber, clogged with plastic:
* open machine and remove-: Restart
feed more slowly.
._
clean
and
3,
d
:z
L
Machine
cuts
slowly
u
-
Knives blunt
fixed or rotating
-
Clearances
wrong:
slacken ,off
fixing
bolts,
adjust
stationary
blades, using
adjustment
bolts,
so there
is only a
paper thickness
between rotating
and
fixed
blades.
Re-tighten'
'fixed
blade
.
securing
boltp.
8
,
s
or chipped:
knives.
resharpen
D
,
that blades are not clogged. Check no
drive belts are broken o'r.stretched.
burlfing'
Machine
- Knives blunt
or material
tough for power'of.machine.
stalls
Crumber
G
Any of the faults
addition:-
or
to t e crumber.'
t '.
In'
F
of the granulator
"*
may apply
Some'material
not
crumbed, remains
flakey
,
- Water added too soon.
Material
wet
- Too much water
comes out
Crumbs adhere
other in&large
too thick
to each
mass
- Insufficient
.
added.
water
added.
EFFECT OF RECYCLING ON POLYMERS
In Appendix
1 it is explained
how certain
polymers
degrade at
temperatures
at or near those
required
for moulding.
,The
operations
of recycling,
especially
of crumbing and pelletizing;
of degradation
and
involve
actual
melting
and
care.
The following
certain
other changes must be watched
notes cover the common polymers:
Polyethylene
The only problem is possible
change in melt flow index - recycled
polyethylene
may have lower melt viscosity
than new material.'
Material
should
be reprocessed
at
the
lowest
po&bIe
temperatures
and held at these temperatures
for as short a time
as possible.
Reclaim should bg tested for melt flow index after
processing
(see Appendix
II)
and differenoea
allowed
for when
I
blending
with virgiq
material.
*
,
-------p
Polystyrene
Slight
yellow
discolouring
can be reduced by, keeping
recycldng
temperatures
and times down.
High impact polystyrene
should be
dried before reprocessing
as it absorbs water in service.
I
-65
:
Polypropylene"'
Melt flow changes may be g~r&&er than with
polyethylene,
so
It is less
testing
of melt -flow after
prge&tiing
is recommended.
.'Fin the event
of degradation
stable
than~lyethiy‘le-na_and,
a thermal
stabilizer
would need to be mixed with the
occuring,
granulate
prior
to crumbing or pelletizing.
,
ABS
.
Drying before recycling
may ..&a necessary.
properties
of reclaim may [email protected]
virgin
Melt flow
material.
and other
PVC
Both plasticized
and rigid
PVC,qre sensitive
to heat and may have
poor stability
at moulding
temperatures,
depending on the kind of
stabiliser
present.
Keep temperatures
as low as possible,
for as '
short a time as possible.
A further
problem with recycling
PVC ispthe7-presence
of a wide_
variety
of stabilizers,
plasticizers,
fillers
etc in large and
(usually)
unhow~~ quantity
in different
products.'
Normally, such
materials
can only be used to manufacture
low,grade
prodycts.'
However, if scrap-can
be sorted into -similar
categories
(cooking
footballs,
flexible
piping,
oil
bottles,
cable sheathing
etc.)
then the material
is likely
to be suitable
for blending
in the
manufacture
of similar
products.
A sample should be tested to
0 check %eat stability
and, if decomposition
occurs,
advice on a
suitable
stabiliser
should be sought.
The other properties
needed for the proposed use can also be checked.
Polymethyl
_
_
t
methacrylate
,. "
1
The colour
and clarity
of reclaimed
material
is slightly
than that of virgin.
Contamination
by other polymers will
weather resistance
and spoil appearance.
less
reduce
Polycarbonate
This material
in service.
must be dried
.before
recycling,
as. it
.:
,
.
absorbs
>
water
*
'
* ..':,-...
>'
.-?I,.
The-differen&?&,$&
Nylons require
drying before processing.
nylon have different
melting
points and other, characteristics'and
As most sources
of nylon
scrap
should be kept separate.
0
industrial
this is possible.
.,
..
PoSyesters
.,
:
". 0
5
--__.~_
of-pI
are
-, '
;_
,,High purity
'is
essential;
?onfamination
reduces
clarity
and
and requires
high
and
'strength.,
-Reprocessing
is difficult
Material
should
be dried
carefully
controlled
temperatures.
- before processing*
Q*
a
r.
,
Cellulose
acetate and other cellulose
plastics
These materials
need drying
before
recycling.
'
/-
CI '
Y
COSTS OF PROCESSING
when---talc-ulating
~~~ Thefollowin~ctors-willneedto
be included
If
material
passes
through
-4the total
cost of 'processing.
sequence of processes then costs of eachbmust be ,added.
,,;;*<.-c
Total
labour
Total
overhead
Cost of all
soda, gloves;
cost
for
that
Cost/oof'any
-
I
labour
involved
consumables
brushes etc.
'Cost 'of electric:power
.
a
in
or other
or
'L
to machines.
stabilizers
washing
c
_.
cleaning;
'
i
I
I
*
.
additives.
'.I
.Depreciation
'
*
of machines:+
.\'
Interest
on loans to purchase
1
Rent and rates on premises.
I
*
/
I
machines.
,
.:-
Where different
materials
are collected
and processed on the same,
premises it is useful
to calculate
the costs separately
so that
the profitability
of each can be calculated.
(See "Work from
.
Waste", Chaper 18).
"
SAFETY IN PROCESSING
-
0
The importance
of safe working methods and how to achieve them in
a recycling
operation
have been fully
described
in "Work from ,,
Waste".
Some of the main.hazards
of plastics
recyling
must, be
pinwiated
here
as
well:
(1
.
.
:
?
-65-
,
.
Almost all
plastics
Lwill
burn.
Every possible
care to
prevent fire-should
be .taken.
Smoking should not'be allowed. Electrical-machines
shouid.be
unplugged or isolated'at
the end of each day's work.
Fire extinguisher3
or -buckets?-k+*.
:
of water or sand should be kept available.
41'
Granulators
and' crumbers. are powerful
rotating
machine3
which can. cause serious
injury.
They she-uld- be treated
with
and 'never
re8pect
cleaned
or repaired
until
the
electric
supply has been cut off and cannot be accidentally
restored.
The same applies
to.-saws, extruders,
in fa&all
+ ---1...
electrical
machines.
All
electric
machines are potential
sources
of ,electric
shock, especially
in the presence of water.
Care should be
taken to ensure they are correctly
installed
and earthed
and' never repaired
unless electrically
isolated.
Workshop
floors
should be kept dry.
Injection
mouldefs and extruders
generate temperatures
high
enough to cause severe burns.
-Hot plastics
will
stick
to
the skin,and
burn horribly.
Suitableprotective
clothing
must be worn by operators.
Scrap plastics
can carry dirt
or chemicals
that may cause
disease.
Hands should be washed before eating or returning
home after work.
Plastics
can give .off poisonous
fumes when burnt.
Avoid
breathing
such fumes during tests (p.43):
Leave the building quickly
(closing
doors and windows to slow spread of
fire" if possible)
if an accidental
fire
occurs.
Do not
dispose
of plastic
waste by ,burning.
Ensure good room *
ventilation
wherever plas.tics
are processed.
.
‘_
<--
.
-a_
..c-.
.LI_.
~
_
.
MANUFACTUREAND SALE OF SMALL ARTICLES FROM RECLAIM
~---~C'HXPTEr
Recycling
in the manner described
in the last chapter can convert
worthless
scrap into-material
worth between US$400 and US$60? per
tonne (1982 prices)'.
If this material
is moulded into a tiny
product weighing perhaps 5 gms., it may wholesale
at perhaps,f20,
equivalent
to .US$40,000 .per tonne!
There will
of course be
additional
costs,
some of them quite high, which are listed
at
the end of this chapter.
None of them is large compared with the
extra'
income to' be. derived
from moulding
This
to enter the
chapter
describes
the equipment and' skills
'moulding
industry
on the smallest
possible
soale and make far
'
greater
profit.
*.
2
Injection
Moulders
- (Fig.
,r
.
...+
25)
These machines
have an electric
heater
Pressure is,applied
not by a screw but by a
'by turning
a capstan
Heating
time
simple, timer and a .le cycle
(charge,
eject)
takes between
and 45 seconds. ,
limited
to' not more th
a thousand items.,in
around
the. barrel.
plunger,
forced down
is controlled
by a
heat,' inject,
cool,
Production
is thus
an eight hour day. l
These machines are ve
all which limits
the'size
and weight of
the product:
For examp
the SPl"made by the Small Power Machine
Company can plasticize
up to 1 kg'of polymer 'per'hour,
making 120
shot3 in that time, the maximum area of the mould (and hence of
L-.-"
--the product)
is just ZiYier 40 sq cm and the maximum dimensions of
the mould are 1Ocm x 10,cm x 7,5cm._
'
. j
.
"'
Most companies offer 'a range of dies off the shelf and a service'
for making those not included
in the catalogue.
Moulds are made
in aluminiumand
are expected to have a life
of at least 20,00d
components. They cost about US$200 each but could be made cheape 8
in
,., worksho~a.............,.,...
....I_
_.,,,... ,,, ...(local
.,,. ..,._
_
A,range'of
components' Citable
for moulding on a machine of this
size is given in Table 5, and illustrated
in Fig. 26.
.::
0
:
,
1
1
'
' It is not intended
to ,deal with any of the industrial
machines
described
in Cha ter
7 with
their
expensive,
complicated
electronic
controls.
many books are available
for this.
Cheaper *
altsrnatives
are ava'
L
ble.
The kind of extruder'
described
in
Chapter 5 is available
fr_om‘ Indi,a at about US$8,000 at the very
cheapest.
A range of hand;operated
injectilon
moulding and blow i
mouldkng machines exists
that cost less th n US$2,000 '(or less
4
than US$l,OOO from India)
and are therefoire
within
the price
range of a small project,
fhat 'has spent a Jyear collecting
and
granulating
scrap plastic
and has managed to save some cash -for
I
1 ‘ e
.further
investment.
Small
.
_
- =
~:,
-X
".
!
?
.
,'.
0
-
4.
FIGURE: 25.:
Small
injection
-68-
moulder.
Small
scale
blow moulding
Blow moulding is reported
type
by coupling
a simple
to be possible
with a machine
foot pump to the die.
Selection
Small
of Products
for
The following
technical
selecting
products for
Scale
Injection
of
this
Moulding
I
matters
must be taken into account
small scale injection
moulding:
The weight of the product
weight of the machine.
must not
exceed
when
the maximum shot
/I
The size of the product,
both area facing
the nozzle
maximum di&nsions,
must not exceed those specified
for
machin:.
.-
The material
must be a thermoplastic
?%ost of
for injec'tion
moulding.
'
Table 1 are suitable.
_-* :
and
the
of suitable
the materials
properties
listed
in
The shape of the product
must be such that
withdrawnfrom
the mould.
Thus hollow objects
narrower than their
base are not suitable.
it
can be
with a neck
.
!
Items with a screw, such as bottle
caps, can be moulded but ,,
will
need to be withdrawn
with an unscrewing
motion.
I
i
Items with holes through them, or with metal ins'erts
(kg. a
screwdriver
with a plastic
handle on a steel
blade)
need
special
methods but these are not necessarily
difficult
if.
the mouldmaker knows,his
job.
In addition
conaidered:-
the
following
commercial
factors
need
to
'\ .
:-
-
price
in the shops?
.- _.,. .
Are they already @made'in the country?
Are they imported
.
which case you may get a big advantage?
Is
q*ua>ity
there
a public
y-o
.
be
i
do such items
--Cm4ieve-a
.
I
t
fiat
'
fetch
as good aso‘ther
demand for
these
Q
in
producers?
Ttems?
How should you package them to obtain widest sales and the
best price?
Mount them on printed
card-? Blister
-pack?---------Pack in .a polythene
bag?
Sell
in small
boxes?
An
attractive
pack can easily
double the price
you will
be
able to charge - and will
provide additional
emplo;vment.
:
;
i
_.
"4
3
I
/
What price will
you charge?
Study the prices
of similar
items in, the shops and ask retailers
what they pay for
them, before
them supplies.
You can dim to
'
you offer
charge a price just below what wholesalers'
pay at present
if 'your' quality
is just 'as good, charge less if your .,
quality,is
inferior.
If there is a shortage of these items
in the country you may be able to charge even more than'the
current
price.
/'
a
./ ,
*
Try and sell to two or'three
dif%rent
outlets,
not to just
one.
Then you can chop and change -.or drop ~a bad phyer
without
difficulty.
For details
of the selling
of waste
materials
see "Work from Waste", Chapter 15.
.
An impoirtant
decision
is
whether
to
sell~ough
wholesalers
or retailers.
If you sell
through
retailers
you will
get a better
price-through
wholesalers
you will
find
it
easier
(less
work)
to sell
large
quantities.
Wholesalers
may not buy from you if you also sell direct
to
retailers
in their
area;
Probably
the decision
rests
on
---.
the matter of quantity.
If the number, of items you can
produce 'will
only
satisfy
the needs af two' or three
retailers
then sell through them; if it will
feed twelve or
more then sell through a wholesaler.
,'
I
*_
I
Work out the difference
in price between the two and calculate whether it is worth the trouble
and cost of distri- --bution
to the retailer
in return
for the extra price you
receive.
I
Operation
-
.
l
of a Small
Injection
Moulder
1
1 _
.on to hea t UP, 10 to 15 minutes
The machine is switched
is requirfd.
1
r
:
The mould:bis closed and clamped.
before.
E
it
..
Material
iis placed in. the hopper and a measure3
into the garrel,
where it is heated'.
< .._.........
amount
,
,a
droppedI
-’
After
a -spe~ie~eu~t~~~~e_~~t~ndle
+=tuI-neG
furc*-plastified
'material
through
.the nozzle and into the .d'ie. --Thepressure
is held for a short "dwell
time",
to'ensure
additional
material
flows into the mould to compensate. for shrinkage,
then
released.
After
a' further
pause the mould clamps are released
tind steel pins used to ejectthe
moulding which is now sdlid but
_. _.-..:-L- - --c;I.
still
hot!
.
The next cycle can take place immediately.
4
I
.
,
.
, :
-7O-
q.
;
,I
---
.._
.
,
~;t'
*'F
49-
. as
.
*
.
.
;
Y
1
A, More Ambitious
.
11
/
.-
Machine
A more ambitious
small sca.le injection
moulding machine is widel,y
Although
the material
is injected
lusing
a
used in Egypt.
electric
motor
and
hydraulic
powered
by
a
5h.p.
hydraulic
ram,
has a 7kw electric
heater,
the die clamping
'Pump? and the barrel
system of links
and levers
is done by hand, using an ingenious
The cdst is around US$l,OOC and promoved' by 'a long handle.
ductidn
rates can be achieved that are, not much -less than, those
'of fully
automatic machines'
_
Proh.lems,that
may be encountered
during injection
moulding:
,
Moulding is short or has holes in it or a rough surface
- Mould
is not totally
filled
- press harder on capstan,
operate capstan
If the trouble
persists
it may
faster- or hold pressure
longer.
be necessary
to increase
the size of the gate .- the opening in
the moulYd that allows the plastic!
to enter.
I
Flash - a thin layer of plastic
escapes .around th_e mould - Check
are securely
mould is tightly
clamped to noz4zle, moyld halves
joineq,
if mould is worn'or
damaged. If flash oqly occurs on one
batch'of
material,
its melt flow index may be too high.
-.
.
'Discolouration
of
thin paper between
--, plastic
enters.
material
- reduce
Stabilizer
to the
the moilding
- may be due to
the two mould halves to allow
With PVC it may be due to
amount of heat, or duration
of
polymer.
Place .
burning.
air to escape as
decomposition
of
p
heating
or add a '
\
.
Misshapen
product
'-, product
ejected
from mould before
cool
Too short dwell time fails
to
enough. Material
not homogeneous.
,'top up' heat shrinkage.
-2.1 -)
\
Cracks or defects in moulding - heating
period too short,
po\ er
. did not all melt.
\ F
,,\ ' L-r \
.’
I 5
_--“-.
:
:
I
---x.....-
”
\
*
;;
~,
._-
\
.
I.
,
o--
.
I
’_ _
:.
.;
1
0
:
‘1
u
n
r
.
*
>
*
.
,
.
‘
I-
;
\
'-71-
..
,-
-a
/y
I
*
,
,
L
’
I
TABLE 5
a
Air
.
&all
Mouldable
:e
’ I
freshener
Plastic
.*
Key'tags
holders
Magnifying
Mobiles
School rulers
arig set squares
Screw-driver
handles
YelT-adneslve
coat nooks
Shoe heels and insoles
'Soap dishes and boxes
Spools
Spinning
tops
Statuettes
and models
Su5tcase and briefcase
fe*ert
=.
Tap,washers and hose fittings
Tap spouts and hose aozzles
Thimbles,
darning mushrooms
artificial
o
-
.~ -.
and
Pencil sharpeners
Plastic
flowers and
fruit
I_.
Plastic
wall plugs
Plugs and ca.ps for.
tubular.steel
furniture
'Pbp-on necklaces
h
Replacement petrol
filler
caps
Desk pencil- stands.
Doorstops~and
door
wedges
.'
Draughts or Jacks
,sL
Electrical
components, simple pl*ugs
a
glasses
Office
equipmst
sundries
Cable joints'
Clothes pegs - without
.springs
CoJlar stiffeners
Gombs
Cosmetic boxes
Cotton reels
Crucifixes,
medall'ions
Cupboard knobs/drawer
handles
Cu%in
hooks,rings
and
runners
.
Cycle handlegrips,
pedal
u
rubbers
.
';
'I
(See .Fig 26) -
I
D
Badges
I.
Bangles and rings
*
Basin and bath plugs and
other plumbing
Battery
filler
caps
Beer mats
Bobbles
a
Bo"%X%lids
and caps
Bra buckles/clasps
and
stiffeners
Buckles
Buttons
’
Objects
>
,.
#'
>j'
!
.:
'*
Wall ornaments - fridge
~-ornaments wfth -m&gnets-:-------;
X-ma3 :.--.-----cI.
tree ornaments
- ~~~ __ _ .,
.). Yoyos
eic
_L- ~.--- ---
.
A
/
+-
I
Y
e .
‘5
,/i"
;
i"
.
.
..
\
I
.
. '
. .
D ..
m
s
c
\-72-.
I
.'
-
I
I
-
F
>
:
:
%
.
.
i: .:-
FIGURE 26:
Small moulda6le
objects.
"
.
L
. I
-,
-
i
APPENDIX-I
'ABOUT PLASTICS - THEIR CHEMISTRY,ANC STRUCTURE
t
r*
v
.!.
' The meaning
of "plastic"
, ,,
1
into any fo,rm".
Piastics
do not
"Plastic"
means "can be-moulded
"plasticity")
at all
times;
most
possess this
quality
'(called
at room temperatures
they are
are on1.y truly
plastic
when-hot;
back ?if bent or stretched
solid
and either
break
or- spring
greatly.
,$
,
”
Monomers and polymers
x
..
Plastics,
are mainly
man-made, by chemical
processes
that *start
frequently
petroleum
oil
but also
with various
raw .materials:
basic
material
non-minerhls
'such as cellulose
(the
of plant
cells)
and even milk.
,I
P
Their
nature
-and behaviour
is
considering
their
detailed
structure:
of which they are made.
‘.i
’
.
*
8~ &L;;$j
,-
most,. easily
the "atoms"
understood
by
and "molecules"
-e
0
L
.' n
which are
The plastics
in common * use are based on "polymers"
compounds know-c as ~monomerstl
. either
formed, from simple organic
or by combinations
of chemical
compounds which on their
own do
not make
polymers.
An
example
of
a
monomer
Qs
the
gas
ethylene,
b
obtained
from crude petroleum
oil.
Each polymer, molecule,
is
made.bg joining,
thousands of monomer molecules
together
in a long
chain by a chemical process called
"polymerizatibn"
Each polymer
is quite
different
from-,the
monomer from which it is made: for
example polyethyl,ene,
made by the polymerization
of ethylene,
is
a fl.e+ible
solid
at room temperature,
quite unlike
the gas from
which it is "formed.
_
>,
- .’
Carbon atoms and bonds
'Carbon (symbol C) is #-I "element".
found in nature in different'
forms:
as coal, as graphite
(pencil
lead) and even as diamond.
Although
too small toll be seen, an atom of carbon has a stryctur‘e
. _
py i &id with one"
like a four-faced
'c
arm sticking
out fro
each corner.
The arms can be imagiL
ashaving
hands with which they can join onto
any other atom that has a free hand.
,<y.
-.:
\ 1
_e_ .
1
I
.
The joint
.between two
atoms is called a bond.
It can be thought of as
the two arms and the
clasped hands where they
@~-.&5f--+fij)
c
~~~~sa~~~~~~~~~~~~~~
..,
,
,
.
other atoms in a vast
number of different
ways.
P) .
.
Hydrogen (symbol H) is an element which
exists
in nature as a light
gas
(explosive
when in contact
with the
An atom of hydrogen
oxygen in air).
has only one arm so four hydrogen atoms
can join onto one-carbon
atom to make the
simplest
of all organic
compounds:
well bown
the gas methane, which'is
as the main ingredient
of biogas or
natural
gas.
For simplicity
i
is drawn on flat
paper like this:
t
H-C-H
u
i
It should not be
forgotten
that it is
three dimensional
and
some of the bonds should
actually
be pointing
out
of the paper.
As well as'joining
onto different
atoms, a- carbon
onto another atom of carbon, either
wPth ea-&atom
of its four arms, which is called
.',.
a single
bond:
."
or with‘ two
aihns each (a
double bond)
.
.
atom can join
using only one
b
:"
or with a
.L
%-iple bond . i . '
..','
1
n
.
:
r
An example of a compound in which
two carbon atoms are joined
by a
double bond is ethylene
(chemical
can 7
formula C2v ) whose molecule
be represen ? ed as:
The simplest
addition
polymer
r
,
i
L
- polyethylene
A molecule whose carbon atoms'are
joined by a double bond can
still
be joined to other molecules
if the double bond is replaced
by a single bond, leaving
two arms free.
Such a molecu le is
called
"unsaturated".
J
a
In the case
of ethylene:
.H
;1
:
becomes
c=c
A
-[
H’
I
--'[-
A
H’
G!
I.
’
H
Consider
a container
that holds a monomer gas or liquid.
For
molecule
with
two free arms, the nearest
available
=lY single
atomsto
which to join are those of other,
identical,
unsaturated
molecules.
conditions
exist
to start
the
so, pr,ovid-ed certain
process,
the monomer molecules
join
together
to form a chain
molecule.
It may be extremely
long,
often
several
thousand
atoms; and not every molecule
in a polymer has exactly
the 'same
length;
when speaking of the length or weight of a polymer molecule it is th.e average that is considered.
For example, ethylene
polymerizes
into a‘ chain molecule of polyethylene,
(also. called
polyth_ene)
in this way.
The process,
of simply adding one,
. monomer molecule onto another,
is
called
addition
polymerization.
,I
Jt
I
/I
Because its 'structure
is light,
with no large groups
atoms, polyethylene
is a lightweight
plastic,
of specific
between. 0.91 and 0.9&T which floats
on water; .'
R
I
H.l-4
I
I
or heavy
gravity
I
H
I
M
I
-;:I
I
*
I
,
A
c
An addition
polymer
without
hydrogen
- PTFE
Although
hyd.rogen is one of the most
common elements to which carbon joins,
For example,
it is not the only one.
the monomer tetrafluoroethylene,
which
is like ethylene
in structure:
'
but with fluorine
atoms (symbol F)in
place of hydro,gen, can be plymerized
into polytetrafluoroethylene
better.
whose extremely
; irnown as FTFE, a plastic
iow friction
has many uses besides the
I familiar
coatings
for, non-stick
saucepans.
-I=
I. FI -IF ! ‘I
-i-;-;-c-c-\;- I
F
F.F-F
_
.
q
Other
polyvinyls
Ll'-
Any monomer whosetSmolecule
1
.* ’
'* H
I
I
c -z c
: I
HA
has the form
.-
I
I
For' example,
There are many such groups.
the methyl group (C Hj) has one carboan
and three hydrogen atoms leaving
one arm
free to join the vinyl
strucJure
to form the
monomer propylene
u-i-,I
c
H-C.-H
.HI
'.
I
I,
,
H,ki
6
H
PVC
Its polymer
is called
a vinyl.
The X can represent
either
(_ is a polyvinyl.
a single
atom (such as hydrogen,
as in
0 1
ethylene)
or a group of atoms.
*
b
:
...
h
F
d
I
- polypropylene‘and
7
H
H
l-i
Eecause the C H, side t:roups *{are spacious
but -not heavy,
the
chain molecules
Gill
not pack so tightly
together
as will
those
of polyethylene,
so polypropylene
'is less dense (specific
gravity
(s.g.)
0.90 - 0.91)
The recycler
uses this property
to distinguish it from high density
polyethylene,
which it otherwi'se
resembles.
.
Yhen the X is an atom of the-poisonous
gas chlorine
(symbol
to sterilize
drinking
and swimming'
used
po301 water,
monomer is a gas called
9
ii'
7
C =C
vinyl
chloride
Cl),
the
I
I
H “‘.‘ CI
and the polymer is
polyvinyl
chloride
or PVC, orie of the
' most widely used.
plastics.
'
.
The chlorine
atoms are much heavier
than:n$hose
of hydrogen,
so
that thejpure
polymer is much denser than polyethylene,
with an
s.g. of about
and sinks in water.
-0
Polymersjwith
benzene rings - polystyrene
,One special
arrangement
that carbon atoms tyke up very easily
is
a ring shape, called
the "benzene ring"
i
'
1.4,
I
H
I
_
:....
I
H,
H
-:~c: [-= c’
II
1.
H/ ’ 'c5
'H
.._._
..‘r-
‘> +
c *cl
__--
or
i
"
I
:
t!
.
b
If one atom of hydrogen is removed
from the rig -a'+Ereeq arm i's available
to join onto other atoms. This
structure
is known as phnnyl (C6Hq)
,'
.,
/
, .w 1'
h
HgC'C+-t
= *II
.
H'c.c&l-j
4
+
,
.'
, .,
1';
.
,
-A \-.
-
.--.-.
In some polymers
regarded as-links
benzene rings
in the Brbon
but phenyl groups may best
of as hanging from it.
P
For exa$ple,
a vinyl
with
styrene
a phenyl
can be
chain
.
be thought
-
c-
c-c
group,
f A
\
C.-C-
0
6
a
.
. . .
k
v
.
d.
polymerizes
into one of the most
widely used plastics:
polystyrene.
'
m,
.
I.
1
3
i.
_
fC*--c
y 9
-p+c
is' heavy so that
.atoms,
1.05) and sinks in .water. 8 It
t,hat'wilJ
be explained 6" later.
The phenyl
ring,
with
about
:polystyrene
is dense (s.g.
0 is aiso very brittle,
for reasons
c
;-
'..I
- 'c
.
a.
.,
n
7
_
-g;p
**
Copolymers
- ABS
As weil
as the addition
of identical
monomers it is possible
to
polymerize
different
ones together.
An important
example is the
"co-polymerization"
of styrene
with butadiene,
a monomer whose
presence in rubber gives toughness and resilience,
axld acrylonitrile
which raises
the melting
point'.
The resulting
co-polymer:
acrylonitrile
butadiene
styrene or ABS-, has the easy mouldability'
of polystyrene
without
its weatiess
and brittleness.
-~
Condensation
polymerization
.
- polyester
l
.-.--
_ --
Some pipers
cannot be made by simple addition
of monomers but
the 'chemical
,combination
of two different
compounds-to
require
form a monomer which
is polymerized
in the process.
'The
chemistry
may be complicated
but one important.material
will
be
mentioned
by way of illustration:
Ethylene
glycol
and terephthalic
acid
combine to make water
and ethylene
terephthalate
which polymerizes
into polyethylene
terephthalate
otherwise
known
as polyester,
(Terylene,
Crimplene,
Dacron; or Trevira)
when it
is.a textile
fibre,
or as PET when used for packaging
6r for soft
- .k
drink bottles.
*
1
Other
important
condensation
polymers
are ,the $olyamides,
of
which various
types of--nylon
are the best known examplesi
and the
polyurethanes,
used as foam fillings
in furniture.
Arrangement
.
1
of the
chain
molecules?in
thermoplastics
The above is but a glimpse of the chemistry
of plymers,
covering
some of the materials
that are mentioned
in the text.
It will
also help to discuss hot the ,cha'in molecules
are arranged and the
effect
on the properties
of various
plastics1
The kinds
of
molecules
in the chains
can, now' bp forgotten,
and 'represented
simply like this:'
:
;
*<
4--,: :;f;j:-by,-yyi
s
_1
, - ._-.~ L *
d
or even more 'simply by
just-indicating
the 'main
bonds, ,like .'this:5
~,,
.$6L
y:
a.
j0
%
**I *,;
,.~
.~
a II?
T 4.
h
Because'the
carbon atom is three dimensional
and'can rotate
about'
it;
bonding
arms, which- are angled
to one another,
it is not.
I
accurate
to represent
'8 polymer chain like this';
1
.
<
.
,
*
-.
’
I.
n
#
* 0 1.
v
;.
,,‘.i
3.
B
*
a
A nearer
approximation
would
be to draw it
like
Even then -it must be remembered that it will
and come out of the paper, and may have side
Effect
of heat
this:
be three,
chains:
i
dimensional
_I
on thermoplastics,,
'In a metal,
When any material
is heated the molecules
vibrate.
once a certain
.temperature
(the melting
point)
is preached,
the
and the metal
immediately
becomes
molecules
can move freely
liquid.
The long chains of most polymers however are intertwined
only gradually
as the temperature
with one another
and separate
rises.
This is seen first
as slight
softening
then,
as the
the material
to siiide
past one anothef,
chains
become free
becomes plastic
and will
flow under pressure;
then it may become
Plastics
a stiff
liquid
and perhaps,
finally,
a runny iiquid.
They can be
that soften when heated are called~"thennoplasMcs".
easily
moulded: shaped when hot and then cooled in the new shape. 1
IL some cases the plastic
will
burn,
char or decompose in some
Exactly
how the
other way before the liquid
state
is reached.
material
responds
to heat is very importaii't,
for recycPing
and
R
It can be measured in different
ways,
later moulding operations.
of which the most important
are:Softening
softens.
point
_..-.
-
,the
,
Processing
temperatulre
out moulding operatibns.
Decomposition
damage occurs
-.
temperature
- the
temperature
in the plastic
best
at
which'
-1
temperature
the
plastic
first
at
which
to
the temperature
at
and it "decomposes"
which
chemical
Melt flou index
- a measure of how fast
Temperature,
will
flow under pressures.
plastic,
Expansion and shrinkage
- th C' change
_bp.--the temperature
rises or fhlln.
length
in
. -
at
or
carry
a given
volume
as
, -
1
ib
1
$
‘: :’
Although .a recycler
will
not need to know them until
h'e pro7
.gresses to the stage of melting
material,
for making pellets
fyr,
how they are affectgd
_ example, they are mentioned here to,stress
t B
by the arrangement of the chain molecules.
,,
, '
0
Thermosets
.
j
I
I
I
/./
Another kind of plastic
behaves quite differently
with heat.
At
some monomer5 form "unsaturated
the time of polymerization,
banding
arm5, not joined
to
whose atoms have "spare"
chains"
The increased
molecular
activity,
due to heat (or
other atoms.
the action of certain
chemicals
called
"catalysts"),
causes these
Cross linkage3
'prevent
between the chains.
atoms to "cross link"
the chains sli'ding,
even when heat is applied,
so no softening
Such' materials,
known as "thermosets"
can only be
occur5'Thw
moulded once; at the time of the polymerization
procesq.
They
L cannot be remelted and reformed 50 they are not recyclable.
will
only be mentioned
elsewhere
to list
and identify
them.
or
Examples of thermosetting
,,plastics
are: phenol formaldehyde
Bakelite,
one of the earliest
plastics
to be made and still
use,d
widely
for electrical
plugs and switches;
melamine formaldehyde,
used to make kitchen
laminates
such as Formica and crockery
such
as Melaware;
and the epoxy resins,
widely
used in' electrical
equipment and composition
,floors.
'
'
P
molecules
*
All
common thermoplastics
are formed of saturated
Some molecules,
su%h.as polyurethane,
can
(every bond is used).
so can be *
exist
in both the satura,ted
and unsaturated
states;
either
thermoplastic,
(and possibly
recyclable)
OG thermoset
(not
recyclable).
i
,
.,
Amorphous thermoplastics
.- polystyrene,
PVC and ABS
-I
u'
qI
/
When thous'anda of 'chains,
each made up of thousands
of monomer
to one another,
during
'bolymerizatipn,
molecules,
grow, close
Entanglement
will
be greater
they may end up totally
entangled.
::
if the chains not only grow end to end, but also branch into side
chains,
or if they contain
large or complex groups,
especially
groups,. in
ring3
hanging
from the chain,
such as the phenyl
Plastics
whose chain molecules
are Oarranged in a polystyrene.
random,
and have
tangled2
fashion
are called
"amorphous"
peirticular
propertiesCI
.-.-, - r
- --cs-.-~~
If a force is applied
to try and stretch
the material
the ihains
will'
not smoothly
slide
over one another
but bunch up. b(Such
material
is "brittle"
and unyielding.
It stretches
little,
and
breaks. sudde,nly,
'In the ea'rly days
especially
under impact.
ob,iects made 'cheaply out of polystyrene
soon cracked and broke to
give all plastics
a bad reputation.
,
.,/
/
.
1
.I
'
Amorphous polymers are less dense than might beaexpected
from the
The chains cannot fit
mass of the atoms that make up the chain.
Were it not
closely
side by side but are held somewhat apart.
for this separation
the-brittleness
due to entanglement
would '6e
even worse.
soften
more gradually
and shrink
less
on
Amorphous polymers
cooling
and this is'the
.reason why.PVC, polystyrene
and ABS are
very satisfactory
for moulding complex shapes.
'
*'-
a
polyethylene
_ (, _
. .
Polyethylene
normally
has most of its molecules
arranged -in an
amorphous stru'cture
with chains well.separated.
For this reason,
.
and because the Regularly
,shaped molecules
have few side ,ohains
.
and no large atoms or groups so they do not become. entangled,
it
flexible,
rath'er
slippery
material',
is a soft,
even at normal
1
flowever a:few of the molecules
are arranged
room temperatures..
in neat,
orderly
rows,
similar
to those. of metals':
such 'a
"crystalline".
By certain
production~metfiods
ssible
to increase
the proportion
of molecules
arranged
in this way with .many benefi&s.
The 'chains pack closely-together
o
I giving
higher
density.
(s.g.
between '0.95,'and
0.96 so it still
;
The materi'al
is known as high -density
floats
on water).
' polythene,
Chile the normal, mainly amorphous, material
iB called
Intermediate
low density
polyethylene.
(9 .Q* O;'qr to 6.92).
*"- .
grades, known as medium density,
have an 9.8. of about 0.93. .'
D
0 Because they are so intimately
packed together,
more force is
needed to make the chains slide over one anotiher,
so strength
and
'
.rigidity
of high density
polyethylene'
are high. but,bthe
sliding,
taqkes place smoothly,
"without
entanglement,
so considerable
“
_ yielding
or. stretching
takw
place before
any breakage occurs.
Material
that *behaves 'in this- way is "tough",
the opposite .of
q
.
brittle.
-More heat is needed to separate the.chaiqs
sufficiently
for softening.to
occur, so softening
and melting
temperatures
are
higher
than those of low density
polyethylene.
High density.
'
polyethylene
is increasingly
being used $or products,
such
a
large
buckets
and thin
film
sacks and bags, ,for which
itsB"
I
stiffness
and strength
are an advantage.
7
,. '
Polypropylene8
*
Crystalline
polymers
- high
density
.
/
i
Thes: ,useful
polypropylene.
crystalline
Iproperties
are
Because of the structure-of
even more developed
the'vinyl
monomer
c
.
.
.’
in
_-
:.
1
I
.
8
v
-
L
c
I
.
\
three different.
polymer chain structures
are
described
overleaf,
composition.
all
.have the same chemical
possible
although
can be arranged randomly:
Either
the monomer molecules
or alternating
or all
different
the same way;
,;iJ
ways:
(described
as “oriented”)
y 7 ii’ 7 y:y
-c-c-c-c-c-c-c
!I
&Ii
&,-A
7
ciH3 k
absence i of
with
coupled
The last
of these
arrangements,
in packing of the chains as close as is perbranching,
. results
to produce a, strong,
tough, hard,
mitted
by the methyl groups,
high-spftening-point
plastic
despite its light
weight.
An example of these exceptional
quali tie.s is that hinges can be
moulded into polypropylene
articles
simply by reducing
the thickThe hinge only becomes
ness to a fraction
of a millimetre.
effectiveLwhen
the material
in the joint
is caused to stretch
and
ka-.&~~
.oriented.
Other materials
also al”l?w hinges to be moulded
but, if orientation
does not occur, these soon fail.
‘The size of the polymer chain
Addition
polymerization
can partially
be controlled
to determine
Long
the length to which the polymer chains are allowed to grow.
molecules,
with
a high
molecular‘
weight,
are strongeli/
and
tougher.
They resist
sliding
more and can slide
further
before
large
numbers of “chain
ends come into
line
to create
a weak
is needed to make
place for breakage to occur. Higher temperature
9.0 the
the polymer sufficiently
plastic
to flow under pressure,
increases.
The
as molecular
weight
melt flow index decreases
ability
of the polymer to stand up to attack
by harsh' chemicals
is also increased
because there are fewer vulnerable
chain ends
, exposed.
n
,
_
I
c
R
whatever damages the molecules
and breaks the chains
Conversely,
reduces strength
and toughness.
to reduce the molecular 'weight,
which may involve
either
mecharfical
battering
or. heat
Recycling,
of this
kind.
treatment
of the polymer,
may have some effect
to which the polymer..
Possibly
more important
is the environment
may have been subjected
before
recycling.
In general
"process
scrap" (plastic
waste from. the factory
moulding process,
recycled
on the spot) will
be little
degraded: However, the ultra
violet
light
in sunlight
breaks polymer chains so "post consumer" waste+
especially
if it has been out in the weather,
may have far less
strength
and toughness
after
recycling
than when 'first
moulded
unless special
corrective
,steps are,taken.
8
.
*-.
I
1
'?g
'#
v.
Additives
I’
One final
aspect of polymers needs mention:
the addition
of other
which may or may not themselves be‘polymers,
to modify
materials,
their
properties.
It
is not essential
to know what these
for the recycler
to be aware
additives
are, but it is necessary
of their
possible
presence and that.. he can use them to improve
By far the gre'atest
amount
the quality
of the reclaimed
product.
of additives
(other than colouring?
are used with PVC.
Plasticizers
.I
when. mixed with a plastic,
penetrate
between the
Certain
liquids,
act as a lubricant
and allow them to slide more
polymer chains,
readily,
producing
a more plastic
material.
The degree of
plasticity
depends upon the proportion
of plasticizer
,that
is
per cent is possible.
Plasticizers
are
used: as high as fifty
rigid
principally
used with
PVC which
is normally
a hard,
to
produce
the
familiar
flexible
material
tiown
as
polymer,
plasticized
PVC., used for luggage Tte;;,
,;;;,"pt,':;;
';,";;
Because "of their
presence
plastic1
difficult
to recyc.Je than rigid
PVC.
_~ ~-/.L
.
f
Stabilizers
i
All-plastics
change chemicall;
if subjected
to a high enough
temperatur%.Some burn, others char or decompose wi,thout burning..
If the temperature
at which this occurs is below, or close
point,
then the material
cannot be satisto I the softening
factorily
moulded.
' PVC is the particular
example of this:
although
it does not burn easily
it decomposes, giving
off fumes
of hydrochloric
acid
gas, which
speed up the decomposition,
damage processing
machinery
and discolour
and spoil
the finished
"
I
,
Processing
temperatures
for PVC range betwee% 150°C and
[email protected]
210 C but decomposition
may occur
as low as 180 C so the
They are overcome by ensuring
that the.
difficulties
are great.
period at moulding temperature
is very short,
and by the addition
the temperature
of a stabilizer:
1.a chemical compound that raises
Even stabilized
PVC may not
at which decomposition
takes 'place'.
recyc.le more than two or three times without
decomposition
occurring.
Stabilizers
are not widely
used with polymers other than
c
PVC.
.>'
Y
,
i
-1
Antioxidants
2
Even at normal room temperatures,
some polymers c.an be degraded
This is accelerated
by ultraviolet
light,
by oxygen in the air.
in sunlight.
Temperatures
above normal,'
even though
present
can make the situation
worse.
below decomposition
t;mperature,
They.may break the
These attacks
may have one of two effects.
which happens ;to polystyrene
and polypropylene,
polymer chains;
toughness.
molecular
loss
of
giving
lower
weight
and
Alternatively
they
may cross
link
them,
which
happens
to
polyethylenes,
to give
higher
molecular
weight,
and loss
of
toughness in the finished
product.
.This brittleness
is found in
polyethylene
sacks and other containers
that have been left
out
in the weather f,or a period.
,
L
These..harmful
effects
are countered
by the use of antioxidants.
Low density
polyethylene
requires
very little;
other
polymers,
such as hig.5 density
polyethylene,
polystyrene,
and polyprqpylene
are more sensitive
both during
moulding
and in use and more
_.
antioxidant
is required.
Other
.
additives
I.
"flame retardants‘".*
"impact
modifiers",,
with the polymer.
i
should not 4e conRt:,;ersW&
Inflammability
can be reduced by addition
of
Brittleness
may ,be <reduced .by the use of
rubbery materials
which are physically
mixed
An example is high impact polystyrene,
(which
fused with ABS, a genuine
c~~;;eJe;;P;~.,i",',
"Fillers"
are non pol
_
reasons.)
properties
or reduce the cost of the polymer with which:they
are
,&mixed. For example glass
fibres
are used to reinforce"thermoplastics
like nylon,
polyacetals
and polypropylene.
The result
is called
"g.r.p."
or "f.r.p.".
Such materials
are in. general,
not recyclable.
Of the many other additives
mention need only be
made of the huge range of "colourants"
and "pigments"
that
convert
the natural
white or transparent
appearance of nearly all
pure polymers
into
the infinite
range of bright
Andy attractive
co‘lours that give .plastics-.sg,,~uc~.
sales
appeal.
--.-= - ;
.
,
,
'
'
a
'
I _
c
r
i
'Y
.'
'
Masterbatch
Additives'
are often
mixed with
the polymer
in the form of a
masterbatch- - a quantity
*of the polymer containinp.'a
heavy conCost of masterbatch
may represent
a
centration
of additives.
Foams and expanded polymers
_
Plastic
foams are familiar
in furniture.fillings,
where Fhefoam,
and in packing
where',
is fl.exible,
usually
polyurethane,
is commonly used.'.'.iFoams'
foam, particularly
expanded polystyrene,
. are made by liberation
of a gas within
the moi'ten polymer,
followed
by rapid
setting
Alternatively
the
foaming agent is combined width the polymer and> can be released
when required.
For example polystyrene
granules
are availab'qe
which can"be heated in a mould to both plasticize
the polymer an&\,S
release
the foaming agent.
The shaped foam object
is released
from the mould when cool and set.
carbon
the economics
,
of recycling'foams
.i
dioxide
.are usually
'or
very
nitrog,en
poor.
.-..
c
are .'
.
.
c
7
at a. f.ixed
electrically
heated
anod kept
temperatu<G:
'1.9Q",C. fd:) Vpolyefhylen,es,
230 C fe'r polypropylene.
P / Weights'.(either,'2.16kg,
5 kg or ,21,.6kg) are placed, on the piston.
I through
the nozzle.
and,. 'at‘
The !mo&.$en [email protected]&&5s _
t c?f material
that has extruded
measur.ed time ‘Giter++als,
P
weighed.
, through the nozzle ip cut
r:
.’
8%
.’
*
Melt
.;low 'index
'
3
*
.
i
.T ,
= 600 x Average
Time intArva1
weight of cut-off
between c;t;offs
in gms;
in' seconds:
*
,I
I
.'
'
’
‘i..+
a
‘
b
4
' The nozzle
is 8mm long
-*When-quoting
., H
'
the M.F.1; t+he weight
. . .
A fual'definition
BS. 2782 Part
'
and 2mm in diameter.
of the -test
1. a
i
should
is'found
be specified.
,'
in British
'
p
Standard'
_.
d
r
I
Y---t
. 1
,
<8
-1
,’
.-.
;
_
D
B
0
P
:?
.
I
:
>
3
a
B
‘5.
Wei ght
“4.
1
=.
.I
_
ter
Thermome
.
Steelncylinder
l
//
45
I
-
Qls+ating
jacket
0
P
-
Electric
heating
jacket
--
Piston
.
u
L
.c
I
.
2mm
Nozzle
.
j.
diameter,
>I
.
. .
8mm long
_
w 1
1L
.
FIGURE. 27:
*
R$g for measuring
melt
flow
.
index.
s-
.
:'
h
&..
3.
.‘_
.
*
‘t
_j
.-
1
‘3
,
7(r
I
*
L,
_I’
-.
*,
.
’
5
*
.
,Td_I,
-8
*
-89-,
-
/
C-.:
.-
SMALL EXTRUDERS.
:.
Axsello
Ltd., Unit 21, "Cha??orh Industrial
Chalford.,
Stroud,
Gloucs.,
GL6 8NT,, U.K.
Leistritz,
Marhyrapenstrasse
West Germany.
q
-
Leistritz,
California,
Estate,
's
-I
29-79,.Postfach
*
1640,
.
369,' San'Miguel
92660/U.S.A.
Drive, Newport
_ s ~
Beach,
3
.
-.
-
Axon,
Haharegatan
*
x-
2, Nyrang,
R
,,
d,
S26500 Aszorp,
8.
'
‘:
'R.H:'Windsor
(India)
L% ., E-6, JJ. Road,
Thana Industrial
Estate,
Thana 400 604, India.
Kobite Industries.
31 Shah Industrial
Veera Desai Road,' Andheri (W), P-0.
Bombay 400 058 India:
'And the companies
listed
under
7
L
‘)
~
/.:
~
Estate off
Box 7368,.
.
'
VARIOUS below.
SMALL INJECTION MOULDERS
Small Power Machine Co.Ltd.,
Chippenham, SN14 OBR, Wilts,
Bath Road Industrial
U.K.
Estate,
I
Griffin
and George Ltd.,
P-0. Box 14, 285 Ealing
Alperton,
Wembley, Middlesex'HAO
IHJ, U.K.
Road,
:
;'
,
Fon and Offord Ltd.,
Alma Street,
Aston, I
Birmingham Bl9 2RP, United Kingdom ,,'s l_l_
- -.'
GRANULATORS*.
*
Condux-Werk,
Redhill,
0645,.
Surrey
I
.I
Estate,"
,
427-,467 Caledonian
:(
I ,
/'
I
e
Boolani Engineering
Corp., Prabhadevi
Industrial
402 Veer Savarkas Marg, Bombay 400026/India.
'
Florin
Ltd,, Manumold Division,
London N7 9BB, United Kingdom.
/ '
I
ti
%
Roa.d,'
. ,*
'
L
i
. I
2
*
H:an,an .11..,:.Wolfgang,
RHI 2NL, U.K..
.: -'
West ,Ger$a"n$: -- 'A<'
..
..,~ I ,.II....
;.T. -~~~~
,.
- t
Ltd.,
,, ._\, ,,,
(who also
,,
9
.
P.0. Box 6065, Providence,
'Leeaona.Cumberland,
Rhode Island,
02940 U.S.A, or Daniels Engineering
CL5 YTL, U.K.
Bath Road., Stroudr Glouceatertihire
recovery
systems).
supply
5omplete
.*
-
And the companies 'listed'-under
, Granulator
Knives
VARIOUS below.
.
.
A-F. Whiteley
&Co.Ltd.,
"Bingswood.Road,
Stockport,
Cheshire SK12 7NB, U.K.
Whaley Bridge,'
..
.
I.
, "1
FOAM RECYCLING‘PLANT
Ryburn Foam, Springwood
Halifax,
HX4 9BL, U.K.
Mills,
)
Holywell
Green;'
CRUMBERSAND RECYCLING PLANT
, .
Kraus Maffei Aktien eseellachaft,
AKraua -Maffei Straase
(Manufacture
Condor
D-8000, Munich, 50,a nAu3tri.e
Machines).
'3 1%
.Buchau-Wolf,
69, 4048 Grevenbroich.
.
1
- *
., '
Fbm di F. Falzoni,
44012 Bondeno, Ferrara,
Italy.
'
Gelderland
G & D.H. Deutschland,
Grobenz
Plaatmachinea,
er
Straze“j,
D-8071
Puchheim, Munchen,
W.
Germany.
_ ~ ___
__~__
~ -------
-
-
-1
L
Postfach
Kween B Plastics
Ltd.,
The,Old*Manse,
Erdington,
Birmingham 1324 8QA, U.K.
ESA (Yewtree) Ltd.,
Unit
Estate,
Waterloo-Avenue,
9
And ‘the companies
VARIOUS
t .
*I I
*.
I
lisied
l
,
..
"
_
.
,.
..
'
:
\
-,I.
_ ~--1I ..,.
..r.,..
’
;
-#
<
/
0
.“’
.
;
’
.
b
:
1
"
_i
VARlOUS'below.
\ '
Ltd'.',- Yate, Bristol
.
5'
II
Plasplant
'Machinery Ltd .', Bordqn Trading Estate,.
Oakhanger Road, Bo,rdon, Hanta GUY5 9HH, U:K.
.,I
..
,i
Bpurne End,
S.T.D. Plastics,~.Ma'chinery
"Fs17 4AX, U.K.
'v
~
‘2
*.
<
I'
,
r
9
Es:tate,
.under
- -5
_~_._ ~--
No '3, CheJmsley Wood Industrial
Birminghamj
B37 6QQ, U.K.-
."
2_
2 Compton Road,
7 Rose Industrial
U.K.
Extrudaid3
Ltd.,
Buckinghamshire,
.
2,
h,
?a
I
(I
1
.
‘I
?
.
”
J
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,.
.
.
rr
,
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,,
)
,_’
.”
1.
:
-.
,.
-
I
_
-5
Mnchinepy ,rrt.T,td .: ,,25, 'Gbrt"Indus CfiF;l
(WeAt) I$ wbay :?,OC.067 Lnd id-..
..
?'
., .1
.:;
Ts .
'? !" k,;",% .
-I
.
,‘LBoo&,Eng.inee,ring
~ofp.;
Prabh Ia.&e~i I~~duatrial.Egta.~;:,.
402, VeermSava'.rkas‘YMayg, gombajr: 400 .025,, Irrd$a.
1 ,/ '
_ -,;, a, ' .,
-.,
.A
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,-;
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(,'
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8'
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F.,
9 I.
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I.
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Rrimc:q Plas$ic
Est&e;KanditJi
-
..,
I-,
.;c
ia
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r
a
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.
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-, :
.-
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.
.
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.
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I
BIBLIOGRAPHY e
.QJ
P)
I
,'
9
,
:,
' ,_,)
,
~
._
11
)~'~~,,~~Eb~l~d,;
.('.E.
',and
Vogler,
J:Al.
,
Remoulding
thelFuture,‘
i ., ,.C'
..
,;
I+P.L.
1982
_,
,_9
2.
\
.
.
'I
.;t?
_',.'
.Y+,: ,.y;. q(
a'.Gail?,,A.-J. and Hane'ock, E.G., Plas;ics
,
and Synthetic
.
; .. '? ,:,i
*
Rubbers,
Pergamon,
1970
i,*
--,I,
‘2..
>
.'
>' //~. - c ..~ I iv-.v. ,,q; L
,, , .'Cb',
t
V.E., Plastics
in the Modern
. +,+y, COUZ.-J' E.G. and Yarsley,
-';:
1968
World, Penguin Pelickln,
. ;.'..,._A‘.I
:-2
.a
,
:
%
_
_ ‘,’
“,>
,>
.X(
4)
-.
e
,.
_.
1
.,
:
.
,‘.“i
J.H. and John, F:W., Plastics,
Van Nostrand Reinhold,
1974
*
f
S., Pla'stics.Designs
and Materials,.
.
,Studio Vista,
1978,
d
';.Dubdis,
,i
;Kati,
,; 5)
.
Hall,
6)
Milby,
4
8,)
5:
b
1
._.
A
i?
~3
'
Arnold,
.a
_:
-9)
LL.K., Introduction
to Plastics,
Allen & Unwin .
m
(i
Bown;’ J., Injection
Moulding of'Plastic
cGraw-Hill
(U.K.) -Al 979-:-
*
s
,C.-, Polymer Materials,
MacMillan,
1981.
R.V., Plasti,cs
Technology,
,':
;'McGraw Hill,
1973>
'
e -.--‘pi”
10)
11)
12)
'
17)
-<
.?.
Components,
0.
.&
The Plastic's
Institute,
of Thermoplastics,
iThe Elements of InjGction
Moulding
.
Mad'laren
.
RAPRA(Rubb'er and Plastics
Research Assooiation)k
Programqed Learning
Texts Teaching-Manuals
o
'
I' Applied Science ,Publishers
Ltd.,
.
Emminger,- H., A Recycling'Conception
for Plastics
Wastes,
.
.: ...
Recycling
International
1982,
'. _ Verlag fur Umwelttechnik;
,
Berlin.
',b
, *--,
.I
'
'Leidner,.r&,r'.
Plastics.
Waste - Recovery of Economic
'
Value, *Marcel Decker Inc. 1'981.-
14) QVogler,
I
1.
c.
!J.A.,'Work
from Waste -'Intermediate
Technology.
Publicati.ons.Ltd.,
1982.
*
P
-~~ +A.,1,:
‘
:
,,')
,
?s) 'Sittig,
M., Organic and Polymer'Waste
Reclaiming-'
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1~6) Saunders, K.J.;, Identifica,tion
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The Identification
Monograph
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Plastics
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plastic's.journa,ls
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Plastics
and Rubber Weekly (incl,udes
advertisements.for
new -and secondhand machinery and for reclaimed
plastic).
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Europe
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Plastics
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The I.2termediate ‘Technol’sgy Development Group was founded in 1965 by the late I%. E.F.
Schumacher< ITDG,%n independent charity, gathers 2nd disseminates information, and advises
In’ addition, the Group is
on the choice of technologies appropriate for developing countries.
I
. _ also involved in an-expanding programme of work on technology’choice
for Britain.
1 ,
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ri
-_
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. SOME OTHER INTERMEDIATE, ?ECI-&LOGY,
PUBLICATIQ,NS
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k’
iork Eroi k3ste: Recycling wastes to
The Sten-screen
..
‘[Making and using’ :a low-cost
printing
”
1 create”employment
.
J Vogler
’
process -’
,
1
I.
authoritative,
detailed
_
‘Practical,
- I
The combination
of stencil duplicating
handbook that sh~yrs how &nploymnnt can
with- screen process printing enables one
’ be created
by recycling
all kinds of
to build a press for approximately
t”1.0.
refclse’: David Astor:
,
.a
-z: I
_
;
No sophisticated components are required
s
‘for ‘,either Construction
or implementThis book deals tiith wastes, theiriorigins,
i-uses _a&l n?ethods of processing, which
ation. The process is capable of prjnting
new activities
and create
”
a wide range of formats; ‘one_ can a’lso~~ ~
stimylafe
‘I
print upon a variety of materials including
employment.
The book is divided into two
paper, textiles and plasti?s. No electrical
main parts. P.art’ I contains-details
of the
a
-. _
wide. range of materials
that can be
supply is required.
‘I
Illus.
2opp.
E1.95.
recycled
and
the
processes
involved.
Part
-*
,I1 describes how to set up and run a small
I
D
business recycling wastes..
2
February
1982. ISBN 0
How to make’ a Foot-C>perated Pillar Drill ,a
3Y6pp. Illus.
by Paul Smith
‘903031 79 5. E6.50.
_
’
I
This is the latest in a~series of workshop
The Low-cost wooden- duplicator.
Ho& to
manuals demonstrating
me, equipment
,
make it. How to use it
constructing
owr:
-1
thods
of
your
machinery.
Full illustrations
and detailed
The low-cost wooden stencil duplicator- is
*’
~building .instructions are provided for the
-a cheap printings machine whiqh ‘dan 6e
1 made for us-e in schools,- ‘colleges and,
.AmanuEa’cture ‘of’ a foot-oper$ed
vertical
Tne duplicator
is
drill- for use with ‘either metal or wood.
small 0rgQpizations.
made mostly from wood-and you need only
The book ~111 be useful to rural works.hops.,.~.”I..~
.,.___
1
and-training
c&%tCes [email protected] the -w$$k’-2
simple wood-work tools tobuild,
It -is-ve!y- -.
Broken or
as’\ well as to com,mercial manufacturers. i *
j easy to use and maintain.
of workshop t$ol-s.
, damaged parts are simple to replace
Price: E1.95.
.
because, you can probably .make them
v
.
” .,
.
yourself.
~_ -1
The Harnessing of 3raught Animals1
Illus. iC1.95.
by Ian Barwe and IMichael Ayre
Y
; Micro-Hyd.ro:
A Techn)ical Brief
This study concentrates
specifically
on :
/ by Ray Holland
I
*
,
1
i A summary of the present state of the art
1 in micro-hydce
wi-t-h a se&on .e~ the-;
’ economics of m’irrom-hydro G-rstallationand
This is the first of a series1 operation.
! which .will ’ be invaluable
to engineers,
_..A..consultants ---and field- _urorkers- in
This first publication .I. ,
1 developing world.
to
will
also be ’ of great .interest
homesteaders
and others
i smallholders,
. interested in practising self-suffi$en.cy
.
p
0
Price! E2.50..
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