Differential Scanning Calorimetry (DSC) Frequently Asked Questions

Differential Scanning Calorimetry (DSC) Frequently Asked Questions
Differential Scanning
Calorimetry (DSC)
FREQUENTLY
ASKED
QUESTIONS
DSC 4000
DSC 8000
DSC 8500 with Autosampler
DSC 6000 with Autosampler
PerkinElmer's DSC Family
A Beginner's Guide
This booklet provides an introduction to the concepts of Differential Scanning
Calorimetry (DSC). It is written for the materials scientist unfamiliar with DSC.
The differential scanning calorimeter (DSC) is a fundamental tool in thermal
analysis. It can be used in many industries – from pharmaceuticals and
polymers, to nanomaterials and food products. The information these
instruments generate is used to understand amorphous and crystalline
behavior, polymorph and eutectic transitions, curing and degree of cure,
and many other material properties used to design, manufacture, and test
products. While DSCs are manufactured in several variations, PerkinElmer is
the only company to make both single- and double-furnace styles. We have
manufactured thermal analysis instrumentation since 1960, and understand
applications better than anyone in the industry. In the following pages, we
answer common questions about how a DSC works, and what it tells you
about the thermal properties of materials you work with in your laboratory.
Table of Contents
20 Common Questions about DSC
What is DSC?.................................................................................................3
What is the difference between a heat flow and a heat flux DSC?....................3
How does the difference affect me?...............................................................3
Why do curves point in different directions?....................................................4
What is heat capacity?...................................................................................4
Why is measuring the glass transition important?............................................4
Why should I measure melting by DSC?..........................................................5
What else can I learn from DSC data?.............................................................5
How do I obtain good data?...........................................................................5
How can I improve my data?..........................................................................6
Why doesn’t my data agree with other thermal techniques?............................6
What is the difference between controlled and ballistic cooling?......................6
Why should I care about isothermal performance?..........................................7
How do I study oxidative stability?..................................................................7
When do I need to use HP-DSC?.....................................................................7
When should I consider using UV-DSC?..........................................................7
How are kinetic studies done with a DSC?......................................................7
What is Modulated Temperature DSC?............................................................7
What is Fast Scan DSC or HyperDSC®?............................................................8
What hyphenated techniques work with DSC?................................................8
Glossary............................................................................................................... 8-9
Additional Resources............................................................................................. 9
2
20 Common Questions about DSC
Q
What is DSC?
A
ifferential Scanning Calorimetry, or DSC, is a thermal
D
analysis technique that looks at how a material’s heat
capacity (Cp) is changed by temperature. A sample of
known mass is heated or cooled and the changes in its
heat capacity are tracked as changes in the heat flow.
This allows the detection of transitions such as melts,
glass transitions, phase changes, and curing. Because of
this flexibility, since most materials exhibit some sort of
transitions, DSC is used in many industries, including
pharmaceuticals, polymers, food, paper, printing,
manufacturing, agriculture, semiconductors, and electronics.
materials were first seriously studied by the ceramic
industry in the 1800s using differential thermal analysis
(DTA). This early work was done by placing a thermometer
into a material and heating it in an oven, similar to the
way a meat thermometer is used. There were some serious problems with this as placement of the thermometer
was often not reproducible. This was solved by S. L.
Boersma’s development of the fixed thermocouple
differential thermal analyzer. Analyzers of this design
are still common today and are called Boersma
Differential Thermal Analysis (DTA).
In the 1960s, Mike O’Neill of PerkinElmer developed the
first double-furnace, or power controlled DSC in order to
measure heat flow, the movement of heat in and out
of a sample, directly. This instrument uses a feedback
loop to maintain the sample at a set temperature while
measuring the power needed to do this against a reference
furnace. This allows for very precise control of temperature,
very accurate enthalpy and heat capacity measurements,
and true isothermal performance. Because of its direct
measurement of heat flow, it is often called heat flow DSC.
The biggest advantage of DSC is the ease and speed
with which it can be used to see transitions in materials.
If you work with polymeric materials of any type, the
glass transition is important to understanding your
material. In liquid crystals, metals, pharmaceuticals,
and pure organics, you can see phase changes or
polymorphs and study the degree of purity in materials.
If you are processing or distilling materials, knowledge
of a material’s heat capacity and heat content change
(called enthalpy) can be used to estimate how efficiently
your process is operating. For these reasons, DSC is the
most common thermal analysis technique and is found
in many analytical, process control, quality assurance,
and R&D laboratories.
Q
What is the difference between a heat flow
and a heat flux DSC?
A
The term differential scanning calorimetry refers to both
the technique of measuring calorimetric data while
scanning, as well as a specific instrument design.
The technique can be carried out with other types of
instruments. Historically, temperature transitions in
A Boersma DTA can also be used to calculate heat flow
with the right calibrations and is also used for the DSC
technique. This is accomplished by measuring temperature
differences and changes between a sample and a reference, or the heat flux. These instruments are sometimes
called heat flux DSCs. Like all DTA designs, the Boersma
really measures the temperature difference (T) and
calculates heat flow from calibration data. Because of
their single furnace design, heat flux DSCs are less
sensitive to small transitions, heat and cool at slower
rates than heat flow DSC, and give less accurate values
for Cp and enthalpy.
Q
How does the difference affect me?
A
F or the vast majority of simple applications, the data
from both types of instruments are comparable and both
instruments can provide good data. However, both designs
have strengths and weaknesses, and if you are doing more
than just looking at simple glass transitions and melts, you
may need one or the other. Some of the differences are
given in Table 1.
Table 1. Heat Flow Versus Heat Flux DSC.
Fast Heating (250 ˚C/min plus)
Heat Flux
Yes
No
Modulated Techniques
Yes
Yes
Accuracy of Cp Values
High
Moderate
Delta H Accuracy
High
Moderate
Ease of cleaning
Figure 1. Double-furnace design allows the direct measurement of heat flow.
Heat Flow
Very
Moderate
OIT Testing
Moderate
Easy
Isotherm Performance
Excellent
Affected by sample
3
Q
Why do curves point in different directions?
A
As shown in Figure 2, this is a convention based on how
the instruments work. In a heat flow DSC, the endothermic peaks – those events which require energy point
up – because the instrument must supply more power to
the sample to keep the sample and reference furnaces
at the same temperature. In a heat flux DSC, these same
events cause the sample to absorb heat and be cooler
than the furnace, so they point down. The reverse logic
applies to exothermic events where energy is released.
The International Conference on Thermal Analysis and
Calorimetry (ICTAC) sets the convention that curves should
follow this pattern many years ago. Most modern software
systems let you flip the curves as you like.
Figure 2. Above is a comparison of curves for a nylon from a double
furnace DSC (solid line) and a single furnace heat flux DSC (Boersma
DTA). As explained in the test, Endotherms point in opposite directions.
Q
What is heat capacity?
A
H
eat capacity (Cp) is the amount of energy a unit of
matter can hold. Think of a can of green pea soup: it is
a gelatinous mass at room temperature, but as it heats
up in a saucepan it becomes more fluid. Its heat capacity
also increases and the fluid soup at 100 ˚C can hold more
energy than the solid at room temperature. All materials
show this increase in heat capacity with temperature. It is
reported as either J/g, J/Mol, or as calories/g in the
older literature.
As heat capacity increases with temperature, the run of
a real sample should show a slight upward slope toward
a higher temperature. There is also a step change in the
baseline across the melt as the heat capacity of a molten
material is higher than that of a solid. Lack of these
features suggests some form of data manipulation. Of
course, a strong peak will dwarf these features.
Heat capacity may seem academic, but it turns out to have
lots of practical implications, and engineers often need it.
For example, when running an extruder for polymeric or
food products, knowing the heat capacity of the material
can help you figure out how efficient your process is and
whether you are using too much energy. You can use it to
calculate the energy needed to run a distillation or recycle
column, or to estimate how much energy is needed to
keep something at a certain temperature.
4
The standard is water with a heat capacity of 1 J/M,
which means it takes 1 joule of energy to heat 1 cc of
water one degree. Practically, people use sapphire as a
standard, as it is a stable solid, so it does not change much
or become contaminated. It can also be made very pure.
This allows you to measure heat capacity and obtain
very accurate numbers.
Q
Why is measuring the glass transition
important?
A
T he glass transition (Tg) has been called the “melting
of amorphous material” and as unscientific as that is,
it's an adequate description. Amphorus material such
as glass has no organization in the solid state – it is
random. This gives it the transparency that glass has,
among other properties. As you warm it up, its heat
capacity increases. At some point you have enough
energy in the material that it can be mobile. This
requires a fair amount of energy compared to the
baseline increase, although much less energy than the
melting point does. This energy normally appears as a
step change in the instrument baseline – pointing up in
heat flow instruments and down in heat flux.
In non-crystalline and semi-crystalline polymer of any
type – synthetic high polymers such as polypropylene
and polystyrene, natural polymers like rubber, or
biological polymers such as proteins – the glass
transition is the best indicator of material properties.
As the glass transition changes due to either different
degrees of polymerization or modification by additives,
the physical properties of the material change. The relationship of Tg to the degree of polymerization shown in
Figure 3 changes with these alterations.
Similarly, material properties also change dramatically
above the Tg. For example, materials lose their stiffness
and flow, as is the case in molten glass, and their
permeability to gasses increases dramatically leading to
increased spoilage in food products. Lyophilized materials
can collapse and their storage life is shortened as
excipient-drug reactions can increase.
Figure 3. The relationship of Tg with degree of polymerization showing the
Tg critical where the material develops polymeric properties.
Q
Why should I measure melting by DSC?
A
As most people know, melting is often measured using a
simple melting point apparatus. However, the number is
often imprecise and difficult to reproduce. Using a DSC
for this task gives you the melting temperature from a
calibrated and highly precise system. It also gains you
considerably more information about the sample. When
you measure the melting point (Tm) in a DSC, you get
not only the onset of melting, the Tm, but also the peak
temperature, which corresponds to complete melting in
organics and the energy that the melting transition needs
in order to occur. This is the enthalpy of the transitions,
and it is associated with the crystallinity of materials.
(Figure 4). ICTAC standards say you should take the
onset of the melt peak as the melting point for
metals, organics, and similar materials, but the peak
value should be used for polymers.
In addition, you can use the enthalpy of melting to
estimate both purity and degree of crystallinity for
materials. In the case of pharmaceuticals and organics,
you can estimate purity of materials with much more
accuracy by using the leading edge method. This
method is based on the melting point depression caused
by impurities and, if you know the molecular weight
of your material, it may be possible to use this
approach instead of other methods such as
liquid chromatography.
Table 2. Industry Transitions.
Industry
TransitionsPurpose
Pharmacueticals Tg
Collapse or storage temperature, amorphous content
Cp
Processing conditions
Tm
Polymorphic forms, purity, QC
Polymers
Tg
Indicator of material properties, QC, effect of additives
Polymer processing, heat history
Tm
Exotherm
Reactions rate, curing of
materials, residual cure
Cp
Energy needed to process
Tc
Recrystallization times, kinetics
Food
Tg
Storage temperature, properties
Tm
Processing temperature
Q
What else can I learn from DSC data?
A
D
SC can detect any change that alters the heat flow in
and out of a sample. This includes more than just glass
transitions and melting. You can see solid state transitions
such as eutectic points, melting and conversions of different crystalline phases like polymorphic forms, dissolution and precipitation from solutions, crystallization and
re-crystallizations, curing exotherms, degradation, loss
of solvents, and chemical reactions.
Table 2 shows the type of transitions detected by DSC
sorted by industry and use in that industry.
Figure 4. The melting of polyethylene is shown with the melting temperature
calculated at the peak, as is standard for polymers. The area and enthalpy of
melting are also reported.
Q
How do I obtain good data?
A
Initially, obtaining good data means understanding what
good data is. The quality of the data you get is to some
degree subjective. A company measuring the Tg of
polymers being used for injection molding of toys will
have different requirements than someone concerned
with the collapse temperature of a lyophilized cake.
Good data requires at a minimum a valid calibration
with suitable standards, a smooth baseline, and reasonable
separation of the sample peak from any noise in the
baseline. It should be both repeatable and reproducible.
By calibration, it means the instrument has to be set
up against known standards and checked so it gives
reasonable values. How tight the value repeat is
depends on a decision based on needs of the industry.
One company may need a half a degree while another
may tolerate a degree in variation of temperature.
Similarly, how good a baseline you need is driven by
the requirements of your business. The baseline should be
smooth – no bumps or spikes, flat (a flat line, although in
a real sample some slope upward with higher temperature
is expected as the heat capacity increases), and repeatable,
meaning it does not change from run to run.
5
Assuming you know the calibration is valid and the
baseline is acceptable, the transitions should be clearly
visible without excessive manipulations. If the peak
requires multiple smoothing, is difficult to detect from
baseline noise, or is exceptionally distorted, another
technique may be indicated.
Q
How can I improve my data?
A
T here are several ways to improve a weak signal
if everything else is working well. You can easily increase
sample size by running a larger sample, you can run the
same sample faster, or you can use one of the more
advanced techniques, which will be discussed later
(Page 8 – Modulated Techniques or Fast Scanning
Techniques). You should remember that if you increase
sample size, scanning rate, or both, you need to watch
for loss of resolution in your data caused by uneven
heating of the sample. A large sample should ideally
be run at a slower rate and a sample run at faster rates
should be smaller. Both of these help because the heat
flow is a function of sample mass and scanning rate.
In some cases, a more specialized sample pan may be
the answer. Specialized sample pans exist for many purposes. Samples containing solvents can be run in sealed
pans. Samples that evolve gases, such as those containing explosives, may be run in vented pans. Films can
placed in pans that keep them flat. A different material
sample pan may be needed to reduce interactions with
the sample or to allow a higher temperature to be used. If
you look in thermal analysis supply catalogs, you will see a
wide variety of pans for all sorts of specialized conditions.
Figure 5. DSC 8500 with 96-position autosampler.
6
Q
Why doesn’t my data agree with other thermal
techniques?
A
O
ne common question is why DSC data does not always
agree with other methods of analysis. This is most
commonly raised with the difference in values for the
glass transition for DSC and the mechanical methods
of Thermomechanical Analysis (TMA) and Dynamic
Mechanical Analysis (DMA). There are several reasons
for this, but the most important one involves the nature
of the glass transition. The glass transition is really a
Figure 6. DSC 6000 with 45-position autosampler.
range of behavior where scientists have agreed to
accept a single temperature as the indicator per certain
standards. Different industries have used different
points from the same data set that can vary as much
as 15 ˚C. DSC, TMA, and DMA measure different
processes, and therefore, the numbers vary. You can
see as much as a 25 ˚C difference in data from a DSC
to DMA data reported as peak of tan delta.
Q
What is the difference between controlled
and ballistic cooling?
A
C
ooling is often an under-appreciated property of both
DSC and material science in general. How a material is
cooled from its melt defines its heat history, and
the heat history can make a great deal of difference
in a material’s properties. The classical example is
polyethylene terephthalate (PET), which becomes nearly
all amorphous when cooled rapidly from the melt, but
is mostly crystalline when cooled slowly. Since the heat
history is so important in how a material behaves, the
standard operating procedure in plastics is to run a
heat-cool-heat cycle. The first heat shows the material
as received, the cooling step – if done with controlled
cooling – imposes a standard heat history on the material,
while the second heat allows you to compare materials
directly to each other.
Controlled cooling is important as you want the
cooling rate to be as controlled as the heating rate to
get reproducible data. In controlled cooling, a specific
temperature change per minute is specified as a rate
somewhere between 0.1 ˚C/min to 500 ˚C/min, and
should be maintained throughout the experiment. This
is in contrast to ballistic cooling, where the sample is
cooled as fast as possible by either cutting all power to
the DSC furnace or by removing the sample and
dropping it into liquid nitrogen (LN2). Very high rates
of controlled cooling are desirable as some processes
have rates of 800 ˚C /min and high rates allow you to
model them.
Controlled cooling allows the greatest degree of
separation between overlapping peaks and is more
sensitive than melting. Controlled cooling also allows
you to do isothermal recrystallizations studies to see
how a material behaves when a process applies large
temperature drops on a material. With the isothermal
kinetic packages, you can then predict behavior at rates
that have not actually been measured.
Q
Why should I care about isothermal
performance?
A
Isothermal performance means the ability of the DSC
to hold a precise temperature with no drift. This is best
accomplished in a power-controlled DSC as it is designed
to control temperature. Many processes in real life are
actually done isothermally: baking a cake, curing an
aircraft wing, molding plastic parts, etc. Often, the
material is inserted into a set temperature region at a
very different temperature; the cake goes from room
temperature to 150 ˚C or the plastic goes from the molten
state in the extruder to room temperature as a blown film.
This means that the DSC must not only be able to hold an
isothermal temperature precisely, but it must be able to
heat and cool to that temperature rapidly with no underor overshoot. This is another area where a power
controlled DSC has an advantage due to its design.
Q
How do I study oxidative stability?
A
O
xidative Stability, or the Oxidative Induction Time (OIT),
test is often studied in both DSC and TGA. This is
normally done by heating a material to a set temperature
under an inert gas and switching to air or oxygen once
it has equilibrated. The time needed for the material to
begin to burn is then recorded. Normally, in a powercompensated DSC, a flow-thru cover is used to remove
the smoke from the DSC as quickly as possible. (It can
also be used to remove reactive gases generated by the
sample.) Often, it is best to run these tests in a TGA, as
this experiment is very dirty and these instruments are
designed to accommodate such samples.
Q
When do I need to use HP-DSC?
A
H
igh Pressure (HP) DSC is used for several reasons:
first, an oxidative stability test may take too long at
atmospheric pressures to be convenient. An example
would be looking at an antioxidant package in motor oil.
Secondly, some reactions form water or methanol as a
byproduct, leading to foaming in the sample. Higher
pressure suppresses this. Thirdly, some reaction kinetics are affected by pressure and running the reaction
under controlled pressure is needed to study this effect.
Finally, transitions, like the Tg and boiling point, are
responsive to pressure and running DSC under pressure
Figure 7. DSC 6000 with UV-photocalorimeter accessory.
allows you to study that process. For boiling points,
pressure DSC also allows you to calculate the vapor
pressure of the sample.
Q
When should I consider using UV-DSC?
A
U
V-DSC or Photo-DSC is a DSC that has been adapted
to allow the sample to be exposed to UV light
during the run. This can be done with several types
of light sources, including mercury vapor lamps or LEDs,
over a range of frequencies and intensities. UV-DSC
also allows the study of UV-initiated curing systems in
the DSC, such as those used for dental resins, orthopedic
bone cements, hydrogels, paints or coatings, and adhesives.
It complements the technique of UV-DMA, which allows
you to gain mechanical information on these systems.
UV-DSC also allows you to study the efficiency of curing
and to develop kinetic models for curing systems.
UV-DSC is additionally used to study the decomposition
of materials under UV radiation. This can be for understanding the effects on the storage of pharmaceuticals, on
antioxidant packages in polymers and rubbers, on food
properties, or on dyes in sunlight. It is possible to use
kinetics to model the degradation by UV light. Because
of the high intensities of UV available, accelerated testing
is possible.
Q
How are kinetic studies done with a DSC?
A
K
inetic studies on the DSC can be done using scanning
methods, where the sample is either heated through a
temperature ramp, or isothermally, where the sample is
held at a set temperature. In the latter case, the ramp
rate to that temperature should be as fast as possible
to minimize the effect of the ramp. Data from these
methods can be exported to TIBCO Spotfire®, Excel®
or another program for analysis or run through several
commercially available programs. The advantage of
using DSC for kinetic studies is it tends to be faster and
more straightforward than other methods.
7
Q
What is Modulated Temperature DSC?
A
M
odulated Temperature DSC (MT-DSC) is the general
term for DSC techniques, where a non-linear heating
or cooling rate is applied to the sample to separate the
kinetic from the thermodynamic data. In StepScan™
DSC, this is done by applying a series of heating (or
cooling) micro-steps followed by an isothermal hold.
This allows you to separate the data into an Equilibrium
Cp curve that shows the thermodynamic response of
the sample and an isokinetics baseline that shows the
kinetic response. Unlike some other techniques, these
are calculated independently. This technique removes
kinetic noises from transitions, such as enthalpic overshoot
or the curing exotherm, from an overlapping Tg.
Q
What is Fast Scan DSC or HyperDSC®?
A
F ast Scan DSC is the generic term for DSC techniques that
apply very high heating rates to a sample to increase
the sensitivity of a DSC or to trap kinetic behavior. Fast
scan heating rates range from 100 ˚C/min - 300 ˚C/min.,
where HyperDSC heating rates range from 300 ˚C/min 750 ˚C/min. Heating at high rates was originally
developed in power controlled DSC thanks to the small
furnace mass and the best results are still obtained in
these instruments. When heating rates of 100 ˚C/min
- 750 ˚C/min are applied, the response of the DSC to
weak transitions is enhanced. It is then possible to see
very low levels of amorphous materials in pharmaceuticals; measure small amounts of natural products; freeze
the curin of thermosetting compounds; inhibit the cool
crystallization of polymers; as well as the thermal
degradation of organic materials.
Q
What hyphenated techniques work with DSC?
A
D
SC is not normally hyphenated as frequently as is TGA,
but hyphenation has been used. DSC-IR has been used
to look at the evolved solvents from pharmaceuticals
while DSC-MS has been used to look at the composition
of meteorites and lunar rocks. DSC has also been coupled
to FT-IR microscopy to look at changes in a sample during
a DSC run.
The most promising hyphenated technique is DSCRaman, where a sample is irradiated by a Raman laser
as the sample is run in DSC profile. Because of the nature
of the Raman spectrometer, it is ideally suited for this, as
it does not require any processing of reflectance spectra
nor the use of a special transmission path cell.
DSC-Raman shows great potential for the study of
polymorphic materials, polymeric recrystallization,
chain movements at the glass transition, and for
hydrogen bonding polymers.
8
Glossary
Annealing
is the slow controlled cooling of a material from its melt
temperature to room temperature. This employs controlled
cooling rates below 5 ˚C/min. This is used to further study
the effects of structural ordering within the material.
Calorie
is the amount of heat required to raise one gram of H2O
by 1 ˚C.
Crystallization Temperature
is an exothermic event where a liquid changes to a solid.
This is depicted as a peak. The extrapolated onset and
peak temperature characterize this event.
DMA – Dynamic Mechanical Analysis
is the measurement of stiffness and modulus using forced
oscillations as a function of time, temperature, stress,
strain, or frequency.
DSC - Differential Scanning Calorimetry
is an analytical technique that measures the heat flow
rate to or from a sample specimen as it is subjected
to a controlled temperature program in a controlled
atmosphere.
DTA – Differential Thermal Analysis
is a simpler form of DSC often called heat flux or single
furnace DSC.
Endothermic Event
is a thermal event of a material where energy is absorbed by
the material, i.e. melting.
Exothermic Event
is a thermal event of a material where energy is expelled
by the material, i.e. crystallization.
Fast Scanning DSC
is a DSC technique that employs controlled heating
rates above 100 ˚C/minute. It is used to observe subtle
thermal events.
Glass Transition (Tg)
is an endothermic event, a change in heat capacity that
is depicted by a shift in the baseline. It is considered the
softening point of the material or the melting of the
amorphous regions of a semi-crystalline material.
Heat
is a form of energy. Heat is not temperature.
Heat Capacity (Cp)
is the amount of heat required to raise a unit mass of a
material one degree in temperature. Cp = Q/m T, where:
Cp = specific heat, Q = heat added, m = mass of material,
T = change in temperature.
Heat History
is the last thermal excursion the material has experienced.
In polymers, heat history is erasable by heating the
material slightly above the melt temperature and then
quenching or annealing a material to below its glass
transition temperature.
Heat of Fusion (hf)
is the amount of heat per unit mass needed to change
a substance from a solid to a liquid at its melting point.
hf = Q/M, where: hf = heat of fusion, Q = heat added,
m = mass of material.
Isothermal
holding at a certain temperature and observing material
changes in respect to time. An application of an isothermal
experiment is the examining the curing time of an epoxy.
Isothermal Kinetics
kinetics calculated using isothermal temperatures instead
of ramping rates.
Joule
is the SI unit of energy and is approximately equal to 4.18
calories.
Melting Point (Tm)
the temperature at which a materials melts. It is
measured as the peak temperature of an endothermic
event. For metals and pure organics, it is not the peak
temperature, but the extrapolated onset temperature
(To) of the endothermic event.
Morphology
refers to the crystalline properties and non-crystalline
(amorphous) properties of materials.
Quench Cooling
is a DSC technique that employs rapid cooling rates above
100 ˚C/minute. This is used to further study the effects of
rapid crystallization of a material.
Scanning
heating or cooling at a controlled rate.
Specific Heat
see heat capacity. For engineering purposes, specific heat
and heat capacity can be assumed to be equal.
Start-up Transient
is the initial change in the baseline at the very beginning
of a scanning run before the instrument is in complete
scanning rate control.
Temperature
is the degree of heat measured on a definite scale.
TGA – Thermogravimetric Analysis
tracking the change in the mass of a sample as a function
of time and/or temperature.
TMA – Thermal Mechanical Analysis
measurement of changes in sample size or volume as a
function of temperature.
Watt
is the power expended when one joule of work is done
in one second of time.
Additional References
ASTM® E 2161-08 Standard Terminology Relating to
Performance Validation in Thermal Analysis.
ASTM® E 473-08 Standard Terminology Relating to
Thermal Analysis and Rheology.
P. Gabbott, The Principles and Applications of Thermal
Analysis, Wiley-Blackwell: London, 2007.
PerkinElmer, Inc.
940 Winter Street
Waltham, MA 02451 USA
P: (800) 762-4000 or
(+1) 203-925-4602
www.perkinelmer.com
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Copyright ©2013-2014, PerkinElmer, Inc. All rights reserved. PerkinElmer® is a registered trademark of PerkinElmer, Inc. All other trademarks are the property of their respective owners.
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