Characterization of Polymeric Materials byThermal Analysis

Topics

Introduction to DSCIntroduction to TGAApplications

Amorphous Structure and the Glass TransitionCrystalline StructureThermosetsThermal Stability and KineticsHeat Capacity

DSC: The Technique

Differential Scanning Calorimetry (DSC) measures heat flow associated with structure (amorphous and crystalline) and changes in structure (transitions) of materials as a function of time and temperature in a controlled atmosphere.

These measurements provide quantitative and qualitative information about physical and chemical changes in a material.

The utility of DSC comes from the fact that allchanges in structure involve the absorption or release of heat.

DSC: What DSC Can Measure

Transition TemperaturesGlass TransitionsMelting/Crystallinity (J/g not %)Crystallization Time and TemperaturePolymorphic Transformation/StabilityDrug-Excipient IncompatibilityProtein DenaturationMiscellaneous

Thermal/Oxidative StabilityBoiling PointsPurity

Possible Transitions in a DSC Curve

TEMPERATURE

GlassTransition

*Crystallization *Polymorphic Conversion

*Melting *Polymorphic Conversion *Denaturation

Oxidationor

Decomposition

Crosslinking(Cure)

endo

H

EAT

FLO

W

exo

DSC Cell

Some Q-Series DSCs and Cooling Devices

Tzero™ DSC Cell Schematic

Tzero Sensor

Constantan Body

Chromel Wire

Chromel Area Detector

Constantan Wire

Chromel Wire

Base Surface

Thin Wall Tube

Sample Platform

Reference Platform

DISCOVERY DSC

New Sensor - Objectives

Improve sensor flatness to reduce pan/sensor contact resistance variations

Reduce distortion due to thermal expansion difference between chromel area thermocouples and constantan platformsRealize full benefit of Tzero sample pans – reduce pan contact resistance and variation

Optimize thermocouple locationThermocouple should not be in pan/sensor contact zone because inevitable variations in the magnitude and distribution of contact resistance reduces the repeatability of the differential temperature measurementsLocate thermocouple so that ΔT and ΔT0 measurements are unaffected by pan contact resistance variations

Diffusion Bonding Mechanism

Diffusion Bonded Transducer Construction Process

Why Diffusion Bonding ?

Optimum thermocouple placementImproved flatness of pan/sensor contact region by 6xNo alloying of thermocouple by welding

Result – improved repeatability of signals, allowing full realization of advantages of Tzero technique

RESULT : THE PERFECT THERMOCOUPLE….

…IN THE PERFECT POSITION

Discovery DSC Transducer

Discovery DSC: User Interface

TRIOS Instrument Control

TRIOS Running Queue

TRIOS History View

TRIOS Data Analysis Features

Discovery DSC: Baseline Repeatability

-250

-200

-150

-100

-50

0

50

100

150

200

250

-50 0 50 100 150 200 250 300 350 400

Hea

t Flo

w (μ

W)

Temperature (°C)

Discovery DSC Sensitivity

134

136

138

140

142

144

146

148

150

152

154

154 154.5 155 155.5 156 156.5 157 157.5 158 158.5 159

Hea

t Flo

w (μ

W)

Temperature (°C)

0.017 mg Indium, 1ºC/min

16 μW peak height

Discovery DSC Sensitivity

-400

-350

-300

-250

-200

-150

-100

-50

0

50

100

80 85 90 95 100 105 110 115 120 125 130

Hea

t Flo

w (μ

W)

Temperature (°C)

0.229 mg Polystyrene, 5ºC/min

-154

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-152

-151

-150

-149

-148

-147

-146

-145

80 85 90 95 100 105 110 115 120 125 130

Hea

t Flo

w (m

W)

Temperature (°C)

Discovery DSC Sensitivity

0.229 mg Polystyrene, 5ºC/min

~4 μW step change

Introduction to Thermogravimetric Analysis (TGA)

Topics

TGAThe Technique What TGA Can MeasureImportance of TGA in Materials Characterization Instrumentation

TGA: The Technique

Thermogravimetric Analysis (TGA) measures weight loss or gain as a function of temperature, time and atmosphere

TGA measurements are extremely useful in selecting experimental conditions for DSC experiments and for interpreting results

What TGA Can Measure

Temperatures of Weight ChangePercent Weight Loss or GainDecomposition Temperature(s)Decomposition Kinetics (MTGA™)Thermal/Oxidative StabilityUnbound water or solventBound water or solvent (hydrate or solvate)Moisture adsorption/desorption (Sorption Analysis)

Importance of TGA

Always start characterization of any new material with TGA. That data is often critical to the correct interpretation of DSC data. For example:

Is there unbound water or solvent?Evaporation can look like meltingWater/solvent plasticize amorphous material which lowers and broadens TgIf total volatile content (bound and unbound) exceeds 10% by weight, stainless steel hermetic pans will be required to heat above 130°C

TGA Can be Critical

What is the decomposition temperature?The initial stage of decomposition can be endothermic or exothermic.

If endothermic, it can appear as a meltOnce decomposition begins, DSC provides no useful data about the structure of the drugDecomposition products can corrode the DSC cell and affect the baseline quality of future runsAs a guideline, the upper temperature limit of the DSC experiment should not exceed the temperature of 5% weight loss due to decomposition

Thermogravimetric Technology

S

R

SR

Q5000 w/ IR furnace Q5000 w/ HumidityConventional TGA TGA Sorption Analyzer

Temp.& Humidity Control

Discovery TGA

The New Discovery TGA:Features TA Instruments:

Industry Leading Thermobalance Innovative IR Furnace Unmatched Autosampler

In Addition: A New Gas Delivery Module with either Standard 2-Gas or Optional 4-Gas for Switching/Blending CapabilitiesImproved Usability with the New Discovery User InterfaceNew TRIOS Software with Instrument Control/Data Analysis in One Package

High-Sensitivity Thermobalance

Baseline Accuracy and Repeatability

High Sensitivity for Small Weight Loss

Furnace Vertical Section

Sample panSilicon carbide absorber

Thermocouple

Lower heat shieldsOptional

Heated EGAadapter

Ballistic Heating

Reliable Automation

Discovery TGA GDM

Standard 2-gas switching or optional 4-gas switching/blending capabilitiesAll purge gas information is data-logged and automatically saved into the TRIOS data file

4-Gas Blending GDM Schematic

Balance / Base Purge

SampleFurnace

Gas 1 Gas 3 Gas 4Gas 2

Blending Line

Air Cool

Amorphous Structure &

Glass Transition Studies

Amorphous Materials

Amorphous Structure –Randomly oriented moleculesNo long-range orderLiquids, glassy or rubbery solidsMost polymers are either amorphous or semi-crystalline

Characterization of Amorphous Structure

Glass Transition (Tg)Due to amorphous (non-crystalline) structureDue to macro-molecular motion (translational); i.e., the entire molecule is free to move relative to adjacent molecules.Extremely important transition because the significant change in molecular mobility at Tg causes significant changes in physical and reactive properties.

Changes at the Tg

Heat Flow

Heat Capacity

Temperature Below Tg - lower Cp - lower Volume - lower CTE - higher stiffness - higher viscosity - more brittle - lower enthalpy

Glass Transition is Detectable by DSCBecause of a Step-Change in Heat Capacity

-1.0

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

[ –––

–– ·

] Hea

t Flo

w (m

W)

0.5

1.0

1.5

2.0

Hea

t Cap

acity

(J/g

/°C

)

70 90 110

Temperature (°C)Exo Up Universal V3.8A TA Instruments

Polystyrene - Modes of Molecular Motion/Mobility

Vibration

Rotation

Translation

What Affects the Tg by DSC?

Heating RateHeating & CoolingAgingMolecular WeightPlasticizerFiller

Crystalline ContentCopolymersSide ChainsPolymer BackboneHydrogen Bonding

Anything that effects the mobility of the molecules, affects the Heat Capacity, and in turn the Glass Transition

Effect of Heating Rate on the Tg

10.04mg PMMA

Is it a Tg?

If not sure if a transition is a TgRun Heat-Cool-Heat (H-C-H)

If transition is a Tg then it should be present on cooling curve and 2nd heat

Run MDSCA Tg will always show up in the Reversing Curve of a MDSC experiment

Run TMA or DMA

Is this a Tg or a Melt?

-3.0

-2.5

-2.0

-1.5H

eat F

low

(mW

)

100 120 140 160

Temperature (蚓 )Exo Up Universal V4.3A TA Instruments

Now – Is this a Tg or a Melt?

Polycarbonate 7.92mgH-C-H @ 10蚓 /min

-2

0

2

Hea

t Flo

w (m

W)

100 120 140 160

Temperature (蚓 )Exo Up Universal V4.3A TA Instruments

Sample was annealed (aged) for 130 hours @ 135°C

Cool

1st Heat

2nd Heat

Measurement of Amorphous Structure

The size of the glass transition is linearly proportional to the amount of amorphous structure in the sampleFor small molecules, the glass transition is typically a sharp step and its size can be measured by standard DSC if the DSC has a straight baselineFor polymers, the glass transition is typically broader and becomes hard to measure as the crystalline content increases

Quantification of Amorphous Structure

% Amorphous = 0.145/0.353 = 41%

PET -- 9.43mg MDSC .531/40@5

Change in Cp @ Tg is a measure of amorphous structure

Partially Miscible Amorphous Phases

108.59蚓 (H)0.1007J/g/蚓

140.13蚓 (H)0.1313J/g/蚓

105.16蚓 (H)0.2657J/g/蚓

145.60蚓 (H)0.1715J/g/蚓

PC

ABS-PC

ABS

1.2

1.4

1.6

1.8

2.0

2.2

2.4

Rev

Cp

(J/g

/蚓)

80 100 120 140 160Temperature (蚓 )

If not miscible then Tg’s don’t shiftIf completely miscible then one Tg in the middle

ABS-PC Copolymer “Alloy”

Applications: Measuring Crystalline Structure

Semi-Crystalline Polymers

Crystalline Structure –Molecules arranged in well defined structuresConsists of repeating unitsPolymers can have crystalline phases

Length of molecules prevents complete crystallization

Semi-crystalline Polymers –Both amorphous & crystalline solid phasesExamples are most common thermoplastics

Polyethylene, Polypropylene, etc

Melting

Melting – The process of converting solid crystalline structure to liquid amorphous structure

Melting shows up as an endothermic peak in a DSC scanThe energy required to melt the crystalline phase is proportional to the amount of crystalline phase

In most cases sensitivity isn’t an issue with melting transitionsHeating rate doesn’t effect the onset of melting (much), but will effect resolution

Definitions (cont.)

Crystallization – The process of converting either solid amorphous structure (cold crystallization on heating) or liquid amorphous structure (cooling) to a more organized solid crystalline structure

Enthalpy of Melting/Crystallization - The heat energy required for melting or released upon crystallization. This is calculated by integrating the area of the DSC peak on a time basis.

Melting of Indium

157.01蚓

156.60蚓28.50J/g

Indium5.7mg10蚓 /min

-25

-20

-15

-10

-5

0H

eat F

low

(mW

)

150 155 160 165

Temperature (蚓)Exo Up Universal V4.0B TA Instruments

Peak Temperature

Extrapolated Onset Temperature

Heat of Fusion

For pure, low molecular weight materials (mw<500 g/mol) use Extrapolated Onset as Melting Temperature

Melting of PET

249.70蚓

236.15蚓52.19J/g

PET6.79mg10蚓 /min

-7

-6

-5

-4

-3

-2

-1H

eat F

low

(mW

)

200 210 220 230 240 250 260 270

Temperature (蚓)Exo Up Universal V4.0B TA Instruments

Extrapolated Onset Temperature

Peak Temperature

Heat of Fusion

For polymers, use Peak as Melting Temperature

Heat-Cool-Heat of PET

Second HeatFirst Heat

Cool

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5H

eat F

low

(W/g

)

20 60 100 140 180 220 260Temperature (°C)

Baseline Type

Crystallization

Crystallization shows up as an exothermic peak in a DSC scanCrystallization is molten amorphous material changing to crystalline material upon coolingCold-Crystallization is solid amorphous material changing to crystalline material upon heatingSince crystallization is a kinetic transition, heating/cooling rate does effect the onset of crystallization, and will also effect resolution

Crystallization

Crystallization is a kinetic process which is typically studied either while cooling or isothermally, but can also be studied during heating (Cold-Crystallization)Differences in crystallization temperature or time (at a specific temperature) between samples can affect end-use properties as well as processing conditionsIsothermal crystallization is the most sensitive way to identify differences in crystallization rates

Effect of Cooling Rate on Crystallization

0.0

0.5

1.0

1.5

2.0H

eat F

low

(W/g

)

40 50 60 70 80 90 100 110 120 130 140 150 160Temperature (蚓 )Exo Up

POLYPROPYLENEWITH NUCLEATING AGENTS

POLYPROPYLENEWITHOUT NUCLEATING AGENTS

-1.5

-1.0

-0.5

0.0

Hea

t Flo

w (W

/g)

60 80 100 120 140 160 180 200Temperature (蚓 )Exo Up

crystallization

melting

Effect of Nucleating Agents

Cooling

What is Isothermal Crystallization?

• A Time-To-Event Experiment

Annealing Temperature

Melt Temperature

Isothermal Crystallization Temperature

Time

Zero Time

Isothermal Crystallization

117.4 oC

117.8 oC

118.3 oC

118.8 oC

119.3 oC119.8 oC

120.3 oC

0

1

2

3

4

5H

eat F

low

(mW

)

-1 1 3 5 7 9Time (min)

Applications: Characterization of

Thermosets

Thermoset Materials

A “thermoset” is a cross-linked polymer formed by an irreversible exothermic chemical reaction

A common example is a 2 part epoxy adhesiveWith a DSC we can look at the curing of these materials, and the Tg of full or partially cured samples

Thermosetting Polymers

Curing reaction can be followed by monitoring a wide variety of physical properties including:

Heat of reactionHeat capacityViscosityModulusOthers

Curing of a Thermosetting Material

116.07蚓

76.30蚓195.0J/g

20 Min Epoxy Cured in DSC15.15mg @ 10蚓/min

-6

-4

-2

0

2

4

6

8H

eat F

low

(mW

)

0 50 100 150 200

Temperature (蚓)Exo Up Universal V4.3A TA Instruments

Effect of Heating Rate

128.29蚓0.5594W /g

122.26蚓323.9J/g

137.04蚓0.9506W /g

130.12蚓315.5J/g

149.93蚓1.972W /g

141.85蚓315.1J/g

160.93蚓3.431W /g

151.92蚓320.0J/g

172.86蚓5.792W /g

162.53蚓320.5J/g

-2

0

2

4

6H

eat F

low

T4

(W/g

)

100 120 140 160 180 200 220 240Temperature (蚓 )

1蚓 /m in2蚓 /m in5蚓 /m in10蚓 /m in20蚓 /m in

% Cure by DSC

Need Heat of Reaction (Enthalpy) of unreactedmaterial curing

Typically run uncured material in DSCRun cured (partially cured sample) in DSC

Curing of “20-Minute” Epoxy

116.07蚓

76.30蚓195.0J/g

20 Min Epoxy Cured in DSC15.15mg @ 10蚓/min

-6

-4

-2

0

2

4

6

8H

eat F

low

(mW

)

0 50 100 150 200

Temperature (蚓)Exo Up Universal V4.3A TA Instruments

2nd Heat of Epoxy

46.52蚓(H)

20 Min Epoxy Cured in DSC15.15mg Post-cure scan @ 10蚓/min

-6

-4

-2

0

2H

eat F

low

(mW

)

0 50 100 150 200

Temperature (蚓)Exo Up Universal V4.3A TA Instruments

Tg can be clearly seen No residual cure exotherm visible

Epoxy Cured 48 Hours

5 Min Epoxy - 9.85mgCured 2 nights @ RT

-4

-2

0

2

4

Hea

t Flo

w (m

W)

-50 0 50 100 150 200

Temperature (蚓 )

1st Heat @ 10蚓 /minCool @ 10蚓 /min2nd Heat @ 10蚓 /min

Exo Up Universal V4.3A TA Instruments

Reaction Kinetics

The rate of reaction between the components is a function of time, temperature and formulationDSC can be used to measure how a formulation responds to time and temperatureData from DSC experiments can be applied to reaction models to predict reaction rates and required processing conditions

Borchardt & Daniels, single heat rateASTM E698, multiple heat ratesIsothermal, time to peak reaction rate

Epoxy Cure Kinetics

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Hea

t Flo

w (W

/g)

40 60 80 100 120 140 160 180 200 Temperature (°C)

Reaction Order: 0.95Activation Energy: 82.9 kJ/molLog[pre-exp factor]: 10.34 log[1/min]Heat of Reaction: 258.2 J/gStandard Error: 0.0064 1/sec

Thermoset Epoxy -- 5.536mg --10°C/min

Iso Conversion Plots

0

20

40

60

80

100

120 P

erce

nt C

onve

rsio

n (%

)

0 100 200 300 400 500 600 700 800 900 1000 Time (min)Exo up T A I nstruments

60.00°C

70.00°C80.00°C90.00°C100.00°C

Thermoset EpoxySize: 5.536 mgRT to 250°C @ 10°C/min

Applications: Thermal Stability

&Kinetics

Thermal Stability

Thermal StabilityCan be studied by multiple techniquesMay be studied w/ inert or oxidizing atmospheresTGA – Best choice

Weight lossDSC

Change in heat flow (typically exothermic)DSC cell can be contaminated

Can also see the effect in other techniques like DMA & TMA

TGA Profile In Nitrogen and Air

First Step in Materials CharacterizationLook for:

Thermal StabilityVolatilization/Decomposition Temperature

Weight Loss ProfileNumber of Steps

ResidueChar/Ash/Filler Presence

TGA Gives Upper Limit for DSC

496.75蚓 98.00%

511.31蚓 95.00%

99.71%(8.888mg)

563.26蚓

-2

0

2

4

6

Der

iv. W

eigh

t (%

/蚓)

0

20

40

60

80

100

120W

eigh

t (%

)

0 100 200 300 400 500 600

Temperature (蚓) Universal V4.3A TA Instruments

PTFE 8.91mg N2 Purge @ 10°C/min

Decomposition products include Hydrogen fluoride!

Thermal Stability of Polymers

Method Log: 1:Select gas: 1 - N21: Ramp 20.00 蚓 /m in to 650.00 蚓2: Select gas: 2 - Air3: Ramp 20.00 蚓 /m in to 1000.00 蚓

PVC

PMMA

PET

650.00蚓55.59%

650.00蚓5.928%

LDPEPEEK

650.00蚓14.32%

0

20

40

60

80

100

Wei

ght (

%)

50 250 450 650 850 1050

Temperature (蚓 )

Polyethylene Oxidation Temperature

245.22°C

125.54°C

-20

-10

0

10

20H

eat F

low

(mW

)

50 100 150 200 250 300Temperature (°C)

Oxidation Onset Temperature (OOT)

Polyethylene Oxidative Induction Time

200.10 oC

30.43min

-2

0

2

4

6

8H

eat F

low

(mW

)

-5 5 15 25 35 45Time (min)

Oxidative Induction Time (OIT)

Effect of Pressure

Increased pressure of O2 decreases oxidation time

Sample is a Lubricating Grease

Effect of Antioxidant Level

As antioxidant level increases, time to oxidation increases

Sample is a Lubricating Grease with different levels of antioxidants

Paint Drying

Latex paint @ various humidity’s and temperatures

Latex paint

Paint Drying at 25 °C and Various RH

Kinetic Analysis

The rate at which a kinetic process proceeds depends not only on the temperature the specimen is at, but also the time it has spent at that temperature.

Typically kinetic analysis is concerned with obtaining parameters such as activation energy (Ea), reaction order (k), etc. and/or with generating predictive curves.

TGA Kinetics

1st Order Kinetics based on Flynn and Wall methodLifetime Estimation based on Toops and Toops methodPTFE tested at 1, 5, 10 and 20 deg/minSample sizes constantNitrogen purgeConversion levels selected at 1, 2.5, 5, 10 and 20%

Common Thermogram with TGA Scans

75

80

85

90

95

100

105 W

eigh

t (%

)

400 450 500 550 600 Temperature (蚓 ) T A I nstruments

1.0%2.5%

5.0%

10.0%

20.0%

Log Heating Rate versus 1/T

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6 Lo

g[H

eatin

g R

ate

(蚓/m

in)]

1.15 1.20 1.25 1.30 1.35 T A I nstruments

1.0%

2.5%

5.0%

10.0%

20.0%

Check for linearity

Conversion Time versus Temperature

0

2

4

6

8

10

12 C

onve

rsio

n Ti

me

(hr)

400 420 440 460 480 500 520 540 560 Temperature (蚓 ) T A I nstruments

1.0%

2.5%

5.0%

10.0% E: 264.2 kJ/MoleLog Z: 15.55 1/min60 min half-life: 516.1蚓Conversion: 1.0 %

Percent Conversion versus Time

0

20

40

60

80

100

120 Pe

rcen

t Con

vers

ion

(%)

-0.0 0.5 1.0 1.5 2.0 Time (day) T A I nstruments

450.00蚓

460.00蚓

470.00蚓

480.00蚓

490.00蚓

E: 264.2 kJ/MoleLog Z: 15.55 1/min60 min half-life: 516.1蚓Conversion: 1.0 %

Lifetime Plot

Can be adjusted to known value

0.1

1.

10.

100.

1000.

10000.

1E5

1E6

1E7 Li

fetim

e (h

r)

1.3 1.4 1.5 1.6 1.7 1.8 1.9 (1000/K) T A I nstruments

E: 264.2 kJ/MoleLog Z: 15.55 1/min60 min half-life: 516.1蚓Conversion: 1.0 %

275.325.375.425.475.

Temperature (蚓 )

hour

day

week

month

year

decade

century

Heat Capacity

DSC Heat Flow

t)(T,dtdT Cp

dtdH f+=

signal flowheat DSC dtdH

= Weight SampleHeat x Specific Sample CapacityHeat Sample Cp

==

Rate Heating dtdT

=(kinetic) re temperatuabsolutean at

timeoffunction is that flowHeat t)(T, =f

What is Heat Capacity (Cp)?

Heat capacity is the amount of heat required to raise or lower the temperature of a materialCp is the absolute value of heat flow divided by heating rate (times a calibration factor)Most DSC’s do not measure absolute heat flow or heat capacityBaseline subtraction is required on most DSC’s when measuring CpQ1000/Q2000 can measure Cp without baseline subtraction

Heat Flow Due to Heat Capacity

10.04 mg PMMA

Why is Heat Capacity Important?

Thermodynamic property of material (heat flow isn’t)Heat capacity is a measure of molecular motion. Heat capacity increases as molecular motion increases.

Vibration – occurs below and above Tg Rotation – polymer backbone and sidechains (in and above Tg)Translation – entire polymer molecule (above Tg)

Provides useful information about physical properties of the material as a function of temperature

Measuring Heat Capacity

ASTM Method E1269Requires 3 runs

Run Empty pans for baselineRun calibrate (typically sapphire)Run sample

Typical MethodIso for 10 minHeat @ 10°C/minIso for 10 min

Generally considered to be accurate & repeatable to within 5%

Conventional DSC Cp Measurement

x wtRateHeat HF? HFK x Cp MTS

=

HF

endo

0HFMT

HFS

Temp.

Where:K = Calibration constantHFS = Differential heat flow

with sampleHFMT = Differential heat flow

with empty panswt = weight of sample

Conventional Heat Capacity of PET

Baseline

Sample

Calibration

Conventional Heat Capacity of PET

Heat Capacity & the Total Heat for Semicrystalline PET

Direct Cp Measurement –Q2000/Q1000

DSC’s with advanced Tzero™ technology measure absolute heat flow:Baseline is flatAbsolute zero heat flow value established as

part of methodBy knowing absolute values of the heat flow and heating rate, heat capacity is calculated in real time and stored in data fileAccuracy and precision is generally ± 2% with just single run measurements

Direct Cp Measurement

Typical MethodHeat @10°C/min

Sample Size ~10mg

Lowest mass pans possible

Generally considered to be accurate & repeatable to within 2-3%

Direct Heat Capacity

Average Value of 8 Runs at 20°C/min in a Hermetic Pan is 0.893 vs. a TheoreticalValue of 0.902 J/g°C at 97°C. Total Rangeof Results Varied Less Than +/- 2%. SampleWas Replaced At The End of Each Run.

97.00°C0.9111J/g/°C

97.00°C0.8758J/g/°C

-0.5

0.0

0.5

1.0

1.5H

eat C

apac

ity (J

/g/°C

)

0 50 100 150 200Temperature (°C) Universal V3.1B TA Instruments

Direct Cp of Polyamide Resin

55.57蚓 (H)

Polyamide Resin - 10.34mgHeat @ 10蚓 /min

0

2

4

Hea

t Cap

acity

(J/(g

楣C

))

0 50 100 150 200 250 300

Temperature (蚓 ) Universal V4.3A TA Instruments

Temperature Heat Capacity°C J/(g·°C40 1.02950 1.07960 1.15370 1.21480 1.26190 1.302100 1.346110 1.389120 1.434130 1.48140 1.526150 1.576160 1.631170 1.699

Cp by MDSC

Cp can be measured directly in a single runIn MDSC, while you can look at 3 Cp signals, the Reversing Heat Capacity (Rev Cp) is the quantitative CpLong periods will give more accurate measurementsThe Rev Cp constant should be calculated at the same period of the testsGenerally considered to be accurate & repeatable to within 1-2% (or better)

MDSC Conditions for Heat Capacity

Heating Rate; isothermal up to 5ºC/min

Modulation Period120 seconds

Modulation Amplitude; 0.5ºC to 1.0°C

Sample Size; 10-15mg

Epoxy Potting Compound - 42.53mgMDSC 0.8/120@3蚓 /min

0.44

0.46

0.48

0.50

0.52

0.54

0.56

Rev

Cp

(J/(g

楣C

))

0 20 40 60 80 100 120

Temperature (蚓 ) Universal V4.3A TA Instruments

Heat Capacity by MDSC

Temperature Rev Cp°C J/(g·°C10 0.457420 0.468630 0.478740 0.488850 0.499560 0.509870 0.51980 0.527690 0.5358100 0.543110 0.5492

What Affects Heat Capacity?

Anything that effects the mobility of the molecules, affects the Heat Capacity

Amorphous contentAgingSide chainsPolymer backbone Copolymer composition

Effect of Amorphous Content on Cp

Amorphous Cp is greater than Crystalline Cp

Amorphous Content increases Specific Heat Capacity

Crystalline polymers contain more order and thus fewer degrees of molecular motion. Less molecular motion results in lower specific heat capacity.