Differential Scanning Calorimetry (DSC)

Differential Scanning 

Calorimetry (DSC) 

Theory and Experimental Conditions 

Glass Transition 

Melting and Crystallization 

Heat Capacity 

MDSC 

DSC: The Technique 

Differential Scanning Calorimetry (DSC) measures 

the temperatures and heat flows associated with 

transitions in materials as a function of time and 

temperature in a controlled atmosphere. 

These measurements provide quantitative and 

qualitative information about physical and chemical 

changes that involve endothermic or exothermic 

processes, or changes in heat capacity.

TA Instruments DSC’s 

DSC 2010 DSC 2910 DSC 2920 

DSC: What DSC Can Tell You 

�Glass Transitions 

�Melting and Boiling Points 

�Crystallization time and temperature 

�Percent Crystallinity 

�Heats of Fusion and Reactions 

�Specific Heat 

�Oxidative/Thermal Stability 

�Rate and Degree of Cure 

�Reaction Kinetics 

�Purity

DSC: Definitions 

A calorimeter measures the heat into or out of a sample. 

A differential calorimeter measures the heat of a sample relative to 

a reference. 

A differential scanning calorimeter does all of the above and heats 

the sample with a linear temperature ramp. 

Endothermic heat flows into the sample. 

Exothermic heat flows out of the sample. 

DSC: Heat Flow/Specific Heat Capacity 

∆H = Cp ∆T 

or in differential form 

dH/dt = Cp dT/dt + thermal events 

where: 

Cp = specific heat (J/g°C) 

T = temperature (°C) 

H = heat (J) 

dH/dt = heat flow (J/min.) 

mW = mJ/sec 

dT/dt = heating rate (°C/min.) 

assuming work & mass loss are zero

DSC: Measurement of HF and T 

Sample Ref 

chromel alumel 

Ni-Cr Ni-Al 

DSC: Temperature Measurement 

Sample Ref 

Sample Temperature Ts 

constantan 

Cu-Ni 

Platinel Control 

Thermocouple 

Furnace 

Temperature 

Ag 

furnace

DSC: Heat Flow Measurement 

Alumel wire 

(sample temp) 

Sample Ref 

Potential Difference ∆U 

Temperature Difference ∆T 

Heat Flow dQ/dt 

Chromel 

wires (∆T)

DSC: Cell Schematic Diagram 

Chromel 

Disc 

Dynamic Sample Chamber 

Reference Pan 

Gas Purge Inlet 

Heating 

Block 

Alumel Wire 

Chromel Wire 

DSC: Cell Components 

Sample Pan 

Lid 

Chromel 

Disc 

Thermocouple 

Junction 

Thermoelectric Disc 

(Constantan) 

Silver Furnace: for good temperature 

uniformity 

Sample Purge: for excellent oxidative 

stability measurements 

Purge Preheated: for very low noise from 

turbulence 

Air Cool: for fast return to room 

temperature

DSC: Heat Flux Principle 

The differential temperature ( ∆ T) 

between the sample and 

reference is converted to differential heat flow in a way that 

is analogous to current flow in Ohms Law. 

I = E/R where: I = current 

E = voltage (potential) 

R = electrical resistance 

∆ 

Heat Flow = 

T k 1 k 2 where: 

R 

∆T 

= temperature difference (potential) 

R = thermal resistance of constantan disk 

k 1 = factory-set calibration value 

k 2 = user-set calibration value 

DSC: How Heat Flux is Measured 

• Heat flow through the chromel wafer causes a 

temperature difference ∆T. The temperature 

difference is measured as the voltage difference ∆U 

between the sample and reference constantan/chromel 

junctions. The voltage is adjusted for thermocouple 

response S and is proportional to heat flow. 

∆T = ∆U / S ∆T in °C 

∆U in µV 

S in µV/°C

DSC: Related Instrumentation 

• Modulated DSC (MDSC) : sinusoidal oscillation superimposed 

on linear temperature ramp 

• Differential Thermal Analysis (DTA) 

• Pressure DSC (PDSC) 

• Differential Photocalorimetry (DPC) 

• Dual Sample DSC 

• SDT 2960 Simultaneous DSC-TGA 

DTA 

Differential Thermal Analysis (DTA) : measures the temperatures and 

temperature differences (between sample and reference) associated with 

transitions in materials as a function of time and temperature in a 

controlled atmosphere

PDSC 

Pressure DSC (PDSC) : capability 

of operating at elevated pressure or 

at a vacuum (TAI PDSC: 1 Pa - 7 

Mpa) 

DPC & Dual Sample DSC 

•Differential 

Photocalorimetry (DPC) : 

sample is exposed to 

UV/Vis radiation 

•Dual Sample DSC: 

Allows two samples to 

be ran simultaneously

SDT 2960 

•SDT 2960 Simultaneous DSC-TGA: 

measures heat flow and weight changes 

simultaneously 

DSC: Heat Flow Measurements 

Calorimeter Signals 

Time 

Temperature 

Heat Flow 

Signal Change Properties Measured 

Heat Flow, absolute Specific Heat 

Heat Flow, shift Glass Transition 

Exothermic Peak Crystallization or Cure 

Endothermic Peak Melting 

Isothermal Onset Oxidative Stability

DSC: Typical DSC Transitions 

Heat Flow -> exothermic 

Glass 

Transition 

Crystallization 

Melting 

Temperature 

DSC: Experimental Design 

�Available Method Segments 

�Method Design Rules 

�Typical Methods (Examples) 

Cross-Linking 

(Cure) 

Oxidation 

or 

Decomposition

DSC: Available Method Segments 

JUMP ABORT NEXT SEG* 

EQUILIBRATE SAMPLING INTERVAL 

INITIAL TEMPERATURE SELECT GAS 

RAMP EXTERNAL EVENT 

ISOTHERMAL DATA STORAGE 

ISO-TRACK AIR COOL* 

STEP LNCA CONTROL* 

INCREMENT MARK END OF CYCLE* 

REPEAT SEGMENT x FOR y TIMES MODULATE# 

REPEAT SEGMENT x TILL y °C 

* Available on DSC 29XX only 

# Available on MDSC 29XX only 

DSC: Method Design Rules 

�Start Temperature 

�Generally, the baseline should have three (3) 

minutes to completely stabilize prior to the 

transition of interest. Therefore, at 10°C/min., 

start at least 30°C below the transition onset 

temperature 

�End Temperature 

�Allow a three (3) minute baseline after the 

transition of interest in order to correctly select 

integration or analysis limits

DSC: Heating/Cooling Method 

Heating Method 

(NOTE: No equilibrate segment necessary if 

starting at or near ambient temperature.) 

1) Ramp 10°C/min. to 300°C 

Cooling Method 

1) Equilibrate at 300°C 


DSC: Heat-Cool-Reheat Method 

Heat-Cool-Reheat Method 

1) LNCA control: High 


3) Mark cycle end 0 





The first segment in this method allows for rapid cooling

DSC: Oxidative Stability (OIT) Method 

OIT Method 

1) Equilibrate at 60°C 

2) Isothermal for 5.00 min. 



5) Abort next seg. if W/g > 1.0 

6) Select gas: 2 

7) Iso-track for 200.00 min. 

DSC: Modulated DSC Method 

MDSC Method 

1) Data storage: off 

2) Equilibrate at -20°C 

3) Modulate ±1°C every 60 seconds 


5) Data storage: on 

6) Ramp 3°C/min. to 300°C

DSC: Calibration & Sample Preparation 

�Instrument Calibration 

� Differential Heat Flow (Cell Constant) 

� Temperature 

� Baseline 

�Miscellaneous 

� Purge Gas 

� Cooling Accessories 

� Environment 

�Sample Preparation 

�Selecting Experimental Conditions 

�Routine Maintenance/Sample Press 

DSC: Heat Flow Calibration 

�Differential Heat Flow (ASTM E968) 

�Heat of fusion (melting) standards 

�Heat capacity (no transition) 

�Miscellaneous 

� Use specific purge gas at specified rate 

� Calibrate w/cooling accessory functioning if it will be 

used to run samples 

� Single point used for heat of fusion which is typically 

accurate to +/- 1-2% from -50°C to 350°C 

� Calibration should not change w/heating rate

Heat Flow (mW) 

DSC: Heat Flow Calibration 

�Prepare a 10 to 15 mg. sample of indium and premelt 

prior to first use 

�Use this sample a maximum of 10 times 

�Calibrate at least once a month 

�Typical values for cell constant: 1.0 to 1.2 

DSC: Calorimetric Calibration 

5 

0 

-5 

-10 

157.44°C 

Cell Const.: 1.0766 

Onset Slope: -20.82 mW/°C 

Sample: Indium, 5.95 mg. 

CALIBRATION MODE; 10°C/MIN 

CALIBRATION BASED ON 28.42J/g 

-15 

150 155 160 165 170

Heat Flow (W/g) 

DSC: Temperature Calibration 

�ASTM Method E967 

�Pure metals (indium, lead, etc.) typically used 

�Extrapolated onset is used as melting temperature 

�Sample is fully melted at the peak 

� Miscellaneous 

�With metal standards, calibration should change very 

� little with heating rate 

�With metal standards, it is not practical to calibrate for 

�changes in heating rate on polymer samples 


1 

0 

-1 

-2 

-3 

HEATING RATE 

Extrapolated Onset 

156.61°C 

28.36J/g 

-4 

157.09°C 

-5 

PEAK 

150 152 154 156 158 160 162 164 

50 

40 

30 

20 

10 

0 

Deriv. Temperature (°C/min)


�Calibrate at least once a month 

�Use at least two calibration points up to a maximum of 

five points 

�Use tin, lead, and zinc one time only 

DSC: Recommended Temperature & 

Enthalpy Standards 

Enthalpy 

(cell constant) 

Temperature 

�Benzoic acid (147.3 J/g) Tm = 123°C 

�Urea (241.8 J/g) Tm = 133°C 

�Indium (28.45 J/g) Tm = 156.6°C 

�Anthracene (161.9 J/g) Tm = 216°C 

�Cyclopentane* -150.77°C 



�Cyclohexane# -83°C 

�Water# 0°C 

�Gallium# 29.76°C 

�Phenyl Ether# 30°C 

�p-Nitrotoluene� 51.45°C 

�Naphthalene� 80.25°C 

�Indium# 156.60°C 

�Tin# 231.95°C 

* GEFTA recommended 

Thermochim. Acta, 219 (1993) 333. 

# ITS 90 Fixed Point 

� Zone refined organic compound 

(sublimes)

DSC: Traceable Calibration Materials 

�NIST DSC calibration materials: 

�SRM 2232 Indium Tm = 156.5985°C 

� SRM 2220 Tin Tm = 231.95°C 

� SRM 2222 Biphenyl Tm = 69.41°C 

� SRM 2225 Mercury Tm = -38.70°C 

� SRM 2221b Zinc Tm = In Preparation 

�NIST: Gaithersburg, MD 20899-0001 

� Phone: 301-975-6776 

� Fax: 301-948-3730 

� Email: SRMINFO@nist.gov 

� www: HTTP://ts.nist.gov/srm 


�LGC DSC Calibration Materials: 

�LGC2601: Indium (TA p/n: 915060-901) 

� LGC2608: Lead 

� LGC2609: Tin 

� LGC2611: Zinc 

�Laboratory of the Government Chemist, UK 

� Phone: 44 (0) 181 943 7565 

� Fax: 44 (0) 181 943 7554 

� Email: orm@lgc.co.uk


�Certified materials used to establish traceability of 

instrument calibration 

�ISO/GLP certification often requires third party 

calibration of instruments: 

� Service provided by TA Instruments service 

representative using certified materials 

� Certificate of Calibration issued showing traceability 

of calibration to a national laboratory 

DSC: Effect of Heating Rate 

on Indium Melting Temperature 


1 

0 

-1 

-2 

-3 

-4 

Heating Rates = 2, 5, 10, & 20°C/min 

-5 

154 156 158 160 162 164 166 168 170 

Temperature (°C)

DSC: Effect of Heating Rate 

on Indium Melting Temperature 

Heat Rate Onset Peak ∆H 

Onset 

Variation 

to 10°C/min 

2°C/min 156.49°C 156.61°C 28.46 J/g -0.12°C 

5 156.54 156.75 28.45 -0.07 

10 156.61 156.87 28.46 0 

20 156.76 157.08 28.44 +0.15 

DSC: Polymer Sample w/Internal 

Temperature Calibration Material 

2 Layers 

of Polymer 

Film 

Melting Point 

Standard, e.g. 

Indium 

Typical weight of polymer sample is 10mg 

(2 films at 5mg each) with 1-3mg of Indium

DSC: Indium Sample Placed Between 

Two HDPE Film Samples 

Sample: Linear Polyethylene-Indium 

Size: 10.0000 mg 

Method: VarHeat DSC 

Operator: Lab 

Run Date: 11-Jun-97 12:43 

Comment: DSC @ 2,5,10%20°C/min; crimped pans, HS Cmpd 


0 

-2 

-4 

Polyethylene 

Melt 

Indium 

Melt 

-6 

20 40 60 80 100 120 140 160 180 

Temperature (°C) 

DSC: Effect of Heating Rate on HDPE 

and Indium Melting 


0 

-2 

-4 

-6 

Polyethylene 

Melt 

Indium 

Melt 

-8 

20 40 60 80 100 120 140 160 180 

Temperature (°C)


0.5 

0.0 

-0.5 

-1.0 

-1.5 

When Placed Between Polymer Films 

Heating Rates = 2, 5, 10 & 20°C/min 

-2.0 

154 156 158 160 162 164 166 168 170 


DSC: Effect of Heating Rate on Indium Melting 

When Placed Between Polymer Film 

Onset Variation When Calibrated at 10°C/min. 

Heating Rate 

Standard 

Sample 

Polymer Sandwich 

Sample 

2°C/min -0.12°C +.03°C 

5 -0.07 +.16 

10 0 +0.44 

20 +0.15 +0.82

DSC: Baseline Calibration 

�Slope 

�Calibration should provide flat baseline with 

empty pans 

�Polymers should always have an endothermic 

slope due to increasing heat capacity with 

increasing temperature 

�Curvature 

�Not normally part of calibration procedure 

�Can be eliminated if necessary with baseline 

subtraction 

�Curvature can cause errors in analyses 

DSC: Baseline Slope 


0.5 

0.0 

-0.5 

-1.0 

-1.5 

Empty Pans 

10 mg Polystyrene 

-2.0 

20 40 60 80 100 120 140 160 180 200

DSC: Baseline Curvature 


0.1 

0.0 

-0.1 

-0.2 

100 150 200 250 300 350 


SDT 2960 Calibration 

Heating @ 1°C/min 

Heating @ 3.5°C/min 

•DTA Baseline and empty beams 

0.4 

0.2 

0.0 

-0.2 

TGA Weight Calibration calibration weights 

•Temperature Calibration up to 5 temperature 

standards 

•DSC Heat Flow Calibration sapphire 

Heat Flow (W/g)

SDT 2960 DSC Heat Flow Calibration 

•Two scans from ambient to 1500°C at 20 °C/min 

•empty alumina pans 

•sapphire in alumina sample pan 

•Use Thermal Solutions/Thermal Advantage NT 

Software to analyze 

•E-curve will be calculated and transferred to the 

module when the user accepts the results 

DSC: Instrument Preparation 

�Purge Gas 

�Type of purge gas and flow rate affect calibration and therefore 

should be controlled 

�Nitrogen is preferred because it is inert and calibration is least 

affected by changes in flow rate 

�Cooling Accessories 

�If used, they should be operating and equilibriated prior to 

calibration or sample runs 

�Warm-up Time/Environment 

�Electronics should be given at least one hour to stabilize for 

important samples if the instrument has been turned OFF 

�Electronics are effected by ambient temperature. Avoid areas such 

as hoods or near an air conditioner

Cell Constant 

DSC: Recommended Purge Gas Flow 

Rates & Effect of Flow Rate 

Purge Port (mL/min.) 

Module Purge Cool Vacuum 

DSC 2920/2910/2010 50 (N ) 50* 

2 

25 (He) 50 

* Only needed for subambient or MDSC use. Use dry nitrogen or He gas 

Purge Gas Flow Rate Too Slow: Moisture Accumulation and Early 

Aging of the Cell 

�Purge Gas Flow Rate Too Fast: Excessive Noise 

DSC: Effect of Flow Rate on Cell Constant 

1.80 

1.70 

1.60 

1.50 

1.40 

1.30 

1.20 

1.10 

1.00 

Helium Cell Constant 

Nitrogen Cell Constant 

0 10 20 30 40 50 60 70 80 90 100 110

DSC: Sample Preparation 

�Sample Weight 

� Selection of the optimum weight is dependent on a number of factors. 

The sample to be analyzed must be representative of the total sample 

�The change in heat flow due to the transition of interest should be 

in the range of 0.1 - 10mW 

- metal or chemical melting: 10mg 

�The accuracy of the analytical balance 

- sample weight should be accurate to +1% 

DSC: Heat Flow Change During a 

Transition 


1.0 

0.5 

0.0 

-0.5 

-1.0 

-1.5 

69.41°C 

73.37°C(H) 

+ 0.4881mW 

143.70°C 

34.95J/g 

161.17°C 

1.593mW 

-2.0 

40 60 80 100 120 140 160 180 200 220 

Temperature (°C)

DSC: Sample Preparation (cont.) 

�Sample Shape 

� Keep sample as thin as possible and cover as much of the pan bottom 

as possible 

� Samples should be cut rather than crushed to obtain a thin sample 

� Lids should be used with sample pans in order to keep the sample in 

contact with the bottom of the pan 

�Sample Pans 

� Use lightest, flattest pan possible 

� Use hermetic pans to prevent evaporation if it occurs in the same 

temperature range as the transition of interest 

DSC: Experimental Conditions 

�Reference Pan 

�Always use a reference pan of the same type used to prepare the 

sample 

�Never use a material in the reference pan that has a transition in 

the temperature range of interest 

�Because DSC measures the difference in heat flow between a 

sample and reference, the baseline stabilizes faster if the difference 

in heat capacity between the sample and reference is kept small by 

adding weight (same material as pan) to the reference pan so that it 

is similar in total weight to the sample pan.

DSC: Effect of Reference Pan Weight 

on DSC Baseline 


4 

2 

0 

-2 

-4 

-6 

-8 

-10 

Sample: Epoxy 

Weight: Approx. 10mg 

Heat Rate: 20°C 

REFERENCE PAN WITH 2 LIDS 

1.688mW 

REFERENCE PAN WITH 1.5 LIDS 

-0.6018mW 

-1.953mW 

REFERENCE PAN WITH LID 

-10.04mW 

NO REFERENCE PAN 

-12 

90 110 130 

Temperature °C 

150 170 

DSC: Comparison of DSC Tg Using No Reference 

Pan and One of Equal Cp to Sample 


0.2 

0 

-0.2 

-0.4 

-0.6 

Cp REF = Cp SAMPLE 

NO REFERENCE 

-0.8 

90 110 130 150 170


�Heating/Cooling Rates 

�High rates increase sensitivity 

dQ 

dt 

heat flow 

measured 

by DSC 

dT 

= Cp x 

dt 

= heat capacity 

or weight 

of sample 

x heating 

rate 

+ (T, t) f 

+ time dependent 

or kinetic 

component 

�Low rates increase resolution by providing more time at any 

temperature 

�Purge Gas 

�nitrogen increases sensitivity because it is a relatively poor thermal 

conductor 

�helium increases resolution because it is a good conductor 

of heat to or from the sample 


General Summary 

Condition 

To Increase 

Sensitivity 

To Increase 

Resolution 

Sample Size Increase Decrease 

Heat Rate Increase Decrease 

Ref Pan Weight Increase No Effect 

Purge Gas Nitrogen* Helium* 

*instrument should be calibrated with the same 

purge gas as used to run a sample

DSC: Sample Pan Types 

�Pan Type 

�Aluminum 

�Copper 

�Gold 

�Graphite 

�Al Hermetic 

�Al Alodined Hermetic 

�Gold Hermetic 

�High Volume (100µL) 

�Al Solid Fat Index (SFI) 

�Platinum 

DSC: Sample Pan Selection 

Standard Aluminum Pans 

�Upper Temp Limit 

�600°C 

�725°C (in N2) 

�725°C 

�725°C (in N2) 

�600°C (3 atm.) 

�600°C (3 atm.) 

�725°C (6 atm.) 

�250°C (safety lid) 

�600°C (no cover) 

�725°C (no cover) 

Use a thin layer 

Distribute material 

evenly

DSC: Sample Preparation – Hermetic Pans 

DSC: Sample Pan Selection 

Spread Material Evenly 

Do not overfill!! 

�Sample Type Measurement Pan Type 

solid Tg,Tm std., hermetic, open 

(nonvolatile) OIT SFI, open 

Cp std. 

solid (volatile) Cp hermetic 

liquid Tn,Tc,Tg,Tm hermetic, SFI, open 

Cp hermetic 

OIT SFI, open 

aqueous solution Cp,Tm,Tg alodined or gold 

hermetic 

foods/biologicals denaturation high volume

DSC: Recommended Cell Maintenance 

�Cleaning the DSC cell (bakeout) 

(use this procedure for cleaning a contaminated cell) 

�Air purge = 50mL/min. 

�Ramp 20°C/min. to 600°C 

�Isothermal for 10 min. 

�Cool cell to room temperature 

�Brush out cell with fiberglass brush 

�Check for improved baseline performance 

�NEVER use solvents to clean DSC cell 

Thermoplastic Polymers 

Semi-Crystalline (or Amorphous) 

Crystalline Phase 

melting temperature Tm 

(endothermic peak) 

Amorphous Phase 

glass transition 

temperature (Tg) 

(causing ∆Cp) 

Tg < Tm 

Crystallizable polymer can crystallize 

on cooling from the melt at Tc

DSC: Selecting Experimental Conditions 

�Thermoplastic Polymers 

� Perform a Heat-Cool-Heat Experiment at 10°C/min. 

� First heat data is a function of the material and an unknown thermal 

history 

� Cooling segment data provides information on the crystallization 

properties of the polymer and gives the sample a known thermal 

history 

� Second heat data is a function of the material with a known thermal 

history 

DSC: Thermoplastic: Heat/Cool/Heat 


0.4 

0.2 

0.0 

-0.2 

-0.4 

-0.6 

-0.8 

First Heat 

Cooling 

Second 

Heat 

0 20 40 60 80 

300 

250 

200 

150 

100 

50 

0 

[ ] Temperature (°C)

DSC: Thermoplastic: Heat Flow vs. 

Temperature for Heat/Cool/Heat 


0.4 

0.2 

0.0 

-0.2 

-0.4 

-0.6 

Second Heat 

191.41°C 

First Heat 

Cool 

223.01°C 

48.03J/g 

-0.8 

20 40 60 80 100 120 140 160 180 200 220 240 260 280 



�Thermoplastic Polymers (con't) 

Interpreting Heat-Cool-Heat Results: 

One of the primary benefits of doing Heat-Cool-Heat is for the 

comparison of two or more samples which can differ in 

material, thermal history or both 

�If the materials are different then there will be differences in the Cool and 

Second Heat results 

�If the materials are the same and they have had the same thermal history 

then all three (H-C-H) segments will be similar 

�If the materials are the same but they have had different thermal histories 

then the Cool and Second Heat segments are similar but the First Heats 

are different

Selecting Experimental Conditions 

• During first heat the maximum temperature must be 

higher than the melting peak end; eventually an 

isothermal period must be introduced 

– too high temperature/time: decomposition could 

occur 

– too low temperature/time: possibly subsequent 

memory effect because of the fact that crystalline 

order is not completely destroyed 

• For non-crystallizable (amorphous) thermoplastics the 

maximum temperature should be slightly above Tg 

(removal of relaxation effects, avoid decomposition) 

Thermosetting Polymers 

A + B C 

Thermosetting polymers react (cross-link) irreversibly. 

A+B will give out heat (exothermic) when they crosslink 

(cure). After cooling and reheating C will have only 

a glass transition Tg. 

GLUE



�Thermosetting Polymers 

Anneal the sample, then Heat-Cool-Heat at 10°C/min. 

�Anneal approximately 25°C above Tg onset for 1 minute to 

eliminate enthalpic relaxation from Tg 

�First Heat is used to measure Tg and residual cure (unreacted 

resin). Stop at a temperature below the onset of decomposition 

�Cooling segment gives the sample a known thermal history 

�Second Heat is used to measure the Tg of the fully cured sample. 

The greater the temperature difference between the Tg of the First 

and Second Heats the lower the degree of cure of the sample as 

received 

DSC: Effect of Annealing on the Shape 

of the Glass Transition 

0.0 

-0.1 

-0.2 

-0.3 

-0.4 

annealed 

aged 

0 10 20 30 40 50 60 70 80 90 100 

0.4 

0.2 

0.0 

-0.2 

Heat Flow (W/g)



DSC: Thermoset: Comparison of First 

and Second Heating Runs 

-0.04 

-0.08 

-0.12 

-0.16 

-0.20 

-0.24 

First 

Second 

Tg 

Tg 

155.93°C 

102.64°C 

20.38J/g 

Residual Cure 

0 50 100 150 200 250 300 


DSC: Determination of % Cure 

2.0 

1.5 

1.0 

0.5 

0.0 

DSC Conditions: 

Heating Rate = 10°C/min. 

Temperature Range = -50°C to 250°C 

N2 Purge = 50mL/min. 

-5.27°C(H) 

-12.61°C(H) 

NOTE: Curves rescaled and shifted for readability 

145.4J/g 

54.55 % cured 

79.33J/g 

75.21 % cured 

Under-cured Sample 

Optimally-cured Sample

DSC: Characterization of Epoxy Prepreg 

DSC: The Glass Transition (Tg) 

�What is it? 

�How is it observed and measured? 

�What affects the Glass Transition?

DSC: What is the Glass Transition? 

The Glass Transition is the reversible change of the 

amorphous region of a polymer from, or to, a viscous or 

rubbery condition to, or from, a hard and relatively brittle 

one. 

The Glass Transition Temperature is a temperature taken to 

represent the temperature range over which the glass 

transition takes place. 

DSC: Some Properties Affected at Tg 

Physical property Response on heating 

through Tg 

Specific Volume Increases 

Modulus Decreases 

Coefficient of 

thermal expansion 

Increases 

Specific Heat Increases 

Enthalpy Increases 

Entropy Increases 

V, 

1/E, 

CTE 

Cp 

H & 

S 

Tg 

Temperature

DSC: Measurements of the Tg 

endo HEAT FLOW exo 


T o 

1/2h 

1/2h 

T f 

T m 

T o =Temperature of First Deviation ( C) 

o 

T f = Extrapolated Onset Temperature ( C) 

o 

T m = Midpoint Temperature ( C) 

o 

T i = Inflection Temperature ( C) 

o 

T e = Extrapolated Endset Temperature ( C) 

o 

T = Temperature of Return-to-Baseline ( C) 

T i Te T r 

TEMPERATURE (°C) 

DSC: Polyethylene Terephthalate 


-0.6 

-0.7 

-0.8 

-0.9 

-1.0 

40 60 80 100 120 

r 

71. 54° C 

79. 88° C 

0. 3005mW 

o

DSC: What Affects the Glass Transition? 

Heating Rate Crystalline Content 

Heating & Cooling Copolymers 

Aging Side Chains 

Molecular Weight Polymer Backbone 

Plasticizer Hydrogen Bonding 

Filler 

DSC: Heating Rate 

Heating Rate Sensitivity Reproducibility 

(°C/min) 

5 poor very good 

20* good good 

40 very good poor 

* Recommended heating rate for measuring Tg.

Heat Capacity (J/g/°C) 

DSC: Heating/Cooling of Polystyrene 

DSC Heat Flow (W/g) 

0.15 

0.10 

0.05 

0.00 

-0.05 

-0.10 

10 °C/min COOLING 

10 °C/min HEATING 

75 80 85 90 95 100 105 110 115 


MDSC: Heating/Cooling of Polystyrene 

1.00 

0.90 

0.80 

0.70 

0.60 

5 °C/min HEATING 

5 °C/min COOLING 

0.50 

75 80 85 90 95 100 105 110 115

Effect of Cooling Rate on Tg 

Heat Capacity (J/g°C) 

2.0 

1.8 

1.6 

1.4 

1.2 

1.0 

Heat Capacity Measured 

After Cooling at Quench, 

20, 10, 5, 2, 1 and 0.2°C/min 

increased amorphous 

fraction 

Quench 

20 

10 

20 40 60 80 100 120 140 160 


DSC: Effect of Aging on the Glass 

Transition [M. Todoki, Polymer Data Handbook] 

As-Spun 

2 days 

28 days 

196 days 

3 years and 

2 months 

4 years and 

11 months 


0 50 100 150 

0.2 

Cold Crystallization

DSC: Effect of Annealing on Polystyrene 

Sample: 

Size: 

Method: 

Polystyrene; effect anneal @ 95° 

11.6600 mg 

Anneal Times DSC 

Operator: Lab 

Run Date: 3-Jun-97 16:41 

Comment: DSC @ 10°C/min; N2 @ 50cc/min; 12.8mg A1 in ref.; crimped pans 


0.2 

0.1 

0.0 

-0.1 

-0.2 

Anneal Times = 0, 10, 100 & 1000 minutes 

-0.3 

40 60 80 100 120 140 160 


DSC: Effect of Annealing Time at 95°C 

on Shape of Polystyrene Tg 

Heat Fl ow ( W/ g) 

0. 00 

-0.05 

-0.10 

-0.15 

-0.20 

Anneal Times = 0, 10, 100 & 1000 minutes 

-0.25 

80 90 100 110 120 130

DSC: Effect of Molecular Weight 

on the Tg (for Styrene Oligomers/Polymers) 

Molecular Weight Tg 

104 -138°C 

524 - 40°C 

2,210 40°C 

3,100 62°C 

15,100 86°C 

36,000 94°C 

170,000 100°C 

Turi, pg 249 Kumler, 1977 

DSC: Effect of Plasticizer on the Tg 

for Polyamides 

Water Content (%) Tg (°C) 

0.35 94 

0.70 84 

1.17 71 

1.99 56 

2.70 45 

4.48 40 

6.61 23 

10.33 6

DSC: Effect of Filler and Crystalline 

Content on the Tg 

�Decreases magnitude of Cp shift 

�Broadens temperature range of Glass Transition 

�Increases the Tg 

DSC: Copolymers 

Tg (K) 

490 

450 

410 

370 

0 20 40 60 80 100 

PPO (wt. %)

DSC: Effect of Side Chains on the Tg 

for - CH 2 - CH(R)- 

Side Chain Tg (°C) 

-H 

-36 

-CH 

3 

-12 

-CH 

2 

(CH 

3 

) 

64 

−C 

6 

H 

5 

100 

cyclohexyl 

120 

-C 

6 

H 

4 

-(4-C 

6 

H 

5 

) 

161 

DSC: Effect of Polymer Backbone 

on the Tg 

for -O-(CH 2 ) n - 

N Tg (°C) 

2 -41 

3 -78 

4 -84

DSC: Effect of Hydrogen Bonding 

on the Tg 

Polyamide Tg (°C) HBonding 

Nylon 12,2 59 Least 

Nylon 10,2 56 

Nylon 8,2 93 

Nylon 6,2 159 Most 

DSC: Melting and Crystallization 

�Terminology 

�Observations of Melting and Crystallization 

�Crystallinity Calculations 

�Applications

DSC: Terminology 

�Amorphous Phase - The portion of material whose molecules are randomly oriented in space. Liquids 

and glassy or rubbery solids. Thermosets and some thermoplastics. 

�Crystalline Phase - The portion of material whose molecules are regularly arranged into well defined 

structures consisting of repeat units. Very few polymers are 100% crystalline. 

�Semi-crystalline Polymers - Polymers whose solid phases are partially amorphous and partially 

crystalline. Most common thermoplastics are semi-crystalline. 

�Endothermic - A transition which absorbs energy. 

�Exothermic - A transition which releases energy. 

�Melting - The endothermic transition upon heating from a crystalline solid to the liquid state. This process 

is also called fusion. The melt is another term for the polymer liquid phase. 

�Crystallization - The exothermic transition upon cooling from liquid to crystalline solid. Crystallization 

is a function of time and temperature. 

�Cold Crystallization - The exothermic transition upon heating from the amorphous rubbery state to the 

crystalline state. This only occurs in semi-crystalline polymers that have been quenched (very rapidly 

cooled from the melt) into a highly amorphous state. 

�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. 


Observation of Melting 

0.0 

-0.2 

-0.4 

-0.6 

-0.8 

-1.0 

236.94°C 

45.30J/g 

12.73°C 

250.61°C 

Peak Temperature 

Extrapolated Onset Temperature 

Area under the curve (Heat of Fusion) 

Width @ half height

DSC: Melting Points and Ranges 

• To is the onset to melting 

• Tp is the melting peak temperature 

• Te is the end of melting 

Pure, low molecular weight materials (mw

Baseline Types: Linear 


0.3 

0.2 

0.1 

12.20°C 

16.10°C 

22.27(24.02)J/g 

1.754J/g 

0.0 

-20 -10 0 10 20 30 40 

Exo Up Temperature (°C) 

Universal V2.5D TA Instruments 

Baseline Types: Sigmoidal 


0.3 

0.2 

0.1 

12.20°C 

23.04J/g

DSC: Observation of Crystallization 


1.0 

0.5 

0.0 

-0.5 

-1.0 

139.47°C 

36.60J/g 

-1.5 

100 120 140 160 180 200 

DSC: Crystallization Point 

152.62°C 

Te 

Tc 


�Crystallization is a two step process: 

�Nucleation 

�Growth 

163.24°C 

�The onset temperature is the nucleation (T ) 

�The peak maximum is the crystallization 

temperature (T ) 

C 

Tn 

N

DSC: PET/ABS Blend "As Received" 


-0.2 

-0.4 

-0.6 

-0.8 

67. 38° C 

+ 

70. 26° C( H) 

120. 92° C 

111. 82° C 

9. 016J/ g 

STANDARD DSC 

FIRST HEAT ON MOLDED PART 

235. 36° C 

22. 63J/ g 

249. 75° C 

50 100 150 


200 250 

DSC: Calculation of % Crystallinity 

�Sample must be pure material, not copolymer or filled 

�Must know enthalpy of melting for 100% crystalline 

material (∆H lit ) 

�You can use a standard ∆H for relative crystallinity 

For standard samples: 

% crystallinity = 100* ∆H m / ∆H lit 

For samples with cold crystallization: 

% crystallinity = 100* (∆H m - ∆H c)/ ∆H lit 

lit

DSC: Polymer Crystallinity - Polyolefin 

ENDO HEAT FLOW EXO 

0 

∆H 

= 141 J/g 

141 

% Crystallinity = X 100% 

290 

= 49% 

Size: 10.5mg 

Prog: 5° C/min 

DSC: Applications 

2 4 6 8 10 12 14 

TIME (min) 

�Effect of heating/cooling rate 

�Crystallization kinetics 

�Effects of polymer structure/composition 

�Effects of thermal/mechanical processing 

190 

170 

150 

130 

110 

90 

TEMPERATURE (°C)

DSC: Effect of Heating Rate on 

Nylon 66 Melting Behavior 

endo HEAT FLOW exo 

0.2 mW 

1 mW 

5 mW 

5 mW 

10 mW 

0.5°C/min 

2°C/min 

10°C/min 

20°C/min 

50°C/min 

1 240 2 260 280 300 3 4 


DSC: Effect of Cooling Rate on 

Crystallization of HDPE 


70 

50 

30 

10 

32°C/min 

16 

-10 

100 110 120 130 


8 

4 

2 

1 0.5

DSC: Crystallization Kinetics 

�Two step process 

� Nucleation 

� Crystal growth 

�Nucleation may be 

� Natural 

� Induced (using nucleation agents) 

�Thermally influenced process 

� Natural nucleation 

� Crystal growth 

� Modeled by Isothermal Kinetics using the 

Autocatalytic Model 

DSC: Isothermal Crystallization 

Procedure 

�Heat to 10°C above T 

�Hold for 5 minutes to remove local order 

�Cool rapidly to below melt onset (DO NOT 

OVERSHOOT TEMP) 

�Hold isothermally 

�Record time to crystallization peak (t ) 

M 

c

∆T 

Exothermic 

DSC: Isothermal Crystallization of 

Polyethylene Terephthalate 

T 1 

Blank run 

T 2 

T < < T < T 

T 

1 2 3 4 

T 3 

0 1 2 3 4 5 6 

Time (min) 

DSC: Effect of Nucleating Agents 

on Crystallization 

NUCLEATED 

POLYPROPYLENE 

T 4 

NON-NUCLEATED 

POLYPROPYLENE

DSC: Supercooling of Water 


250 

200 

150 

100 

50 

0 

+ 

-15.55°C 

-4.36°C 

+ 

-50 

-30 -25 -20 -15 -10 -5 0 5 10 


DSC: Purity of Pharmaceutical 

Compounds 

Heat Flow (mW/mg) 

-0.8 

-1.0 

-1.2 

-1.4 

-1.6 

-1.8 

-2.0 

-2.2 

Purity: 99.55 mole % 

Melting Pt: 134.9°C 

Depression: 0.24°C 

Delta H: 26.4 kJ/mole 

Correction: 8.11% 

Mol. Weight: 179.2 g/mole 

Cell Const: 0.977 

Onset Slope: 10.14 mW/°C 

Total Area/Partial Area 

0 

2 4 6 

8 

10 

135.0 

134.5 

134.0 

133.5 

133.0 

132.5 

Temperature (°C)

DSC: Effect of Polymer Type 

on Melting 

Class Structure Melting Range 

Polyolefins 

Polyamides 

Polyesters 

Polyphenylene 

-CH 2-CH 2- 

-CH -NH-C(O)-CH - 

2 2 

-CH -O-C(O)-CH - 

2 2 

85 - 174°C 

190 - 265°C 

220 - 270°C 

Sulfides -Ph-S- 300 - 360°C 

DSC: Effect of Molecular Weight 

on Melting 

Olefin Formula Mole. Wt. T m 

(g/mol) (°C) 

C 12H 26 170 -10 

C 24H 50 339 54 

C 30H 62 423 66 

C 35H 72 493 75


DSC: Effect of Hydrogen Bonding 

on Melting 

Polyamide T m H Bonding 

Nylon 12,2 236 Least 

Nylon 10,2 242 

Nylon 8,2 279 

Nylon 6,2 326 Most 

Nylon x,y where: 

x = carbons in diamine section 

y = carbons in diacid section 

DSC: Effect of Annealing 

Poly(ethyletherketone) (PEEK) on Melting 

0.0 

-0.1 

-0.2 

PEEK 

303.61°C 

PEEK annealed 

@ 300°C 

-0.3 

260 280 300 320 340 360 380

DSC: Effect of Draw Ratio 

on Melting Temperature 

Tm (°C) 

137 

133 

129 

1.0 3.0 5.0 7.0 

DSC: Effect of Aromaticity on Melting 

Polymer % Aromatic Melting Range 

-CH 2 -CH 2 - 0 105 - 135°C 

PET 39 250 - 275°C 

-(Ph)-O- 62 300 - 315°C 

-(Ph)-S- 70 300 - 360°C 

λ

DSC: Effect of Branching on Melting 

Polyolefin Branching T m 

LDPE irregular ~ 105°C 

random lengths 

LLDPE irregular ~ 127°C 

fixed lengths 

HDPE none ~ 135°C 

PP regular ~ 150°C 

fixed lengths 

DSC: Melting and Crystallization - 

Summary 

�Melting and crystallization are phase changes from organized solid to 

amorphous phases and vice-versa. 

�Melting is a one-step process while crystallization involves nucleation 

and crystal growth. 

�The enthalpy of melting can be used to measure crystallinity or filler. 

�Any process that makes it easier for molecules to be organized will 

raise the melting temperature.

DSC: Specific Heat Capacity 

�What is it? 

�How is it observed and measured? 

�Methods for calculating specific heat capacity 

�What affects the specific heat capacity of a 

polymer? 

DSC: What is Specific Heat Capacity? 

�Specific Heat Capacity (Cp) is the amount of heat required to raise the 

temperature of one gram of a particular material one kelvin of 

temperature. Specific Heat Capacity is due to the molecular motion in a 

material (units of J/g K). 

�Heat Capacity is the amount of heat required to raise the temperature of a 

material one kelvin of temperature. This is unnormalized specific heat 

(units of J/K). 

�Specific heat is the specific heat capacity of an analyte compared to the 

specific heat capacity of a reference material (dimensionless).

DSC: How are Heat Capacity and 

Specific Heat Measured? 

�In a DSC experiment, heat capacity is measured as the 

absolute value of the heat flow, divided by the heating 

rate, and multiplied by a calibration constant. 

dH/dt = Cp (dT/dt) 

or 

Cp = [(dH/dt)/(dT/dt)] x E 

E = calibration constant 

DSC: How Heating Rate Shifts 

Heat Flow 


0 

-2 

-4 

-6 

-8 

106. 85° C 

-2.137mW 

106. 85° C 

- 40175mW 

106. 85° C 

-8.104mW 

5°C/min 

10°C/min 

20°C/min 

-10 

40 60 80 100 120 140 160 180 200

DSC: Specific Heat Capacity Equation 

Cp = 

E x H x 60 

Hr x M 

�Cp = Specific Heat Capacity (J/g/°C) 

�E = Calibration Constant (dimensionless) 

�H = Heat Flow (mW) 

�60 = conversion constant (min sec) 

�Hr = Heating Rate (°C/min) 

�M = Sample Mass (mg) 


Step 1. Run Empty Pans 

�Create Thermal Method, e.g., 

1) Equilibrate @ 50°C 

2) Isothermal for 10 min. 

3) Ramp 20°C/min to 300°C 

4) Isothermal for 10 min. 

�Run Empty Pans to determine background heat flow 

�Subtract background heat flow from subsequent


Step 2. Determine Value of E 

�E is temperature-dependant 

�Heat sapphire disc (Cp standard) through thermal 

profile 

�At temperature of interest, calculate E 


Step 2. Determine Value of E (cont.) 

�For example, at 380 K (106.85°C), sapphire 

Cp = 0.9161 J/g/°C 

�M = 25.20mg 

�Hr = 20°C/min 

�Measured Heat Flow = 7.25 mW 

E = 

Cp Hr M 

(0.9161 mJ/mg/°C) x (20°C/min) x (25.20 mg) 

(7.25 mW (mJ/sec)) x (60 sec/min) 

H


Step 3. Measure Unknown Sample 

�Use exact same thermal profile as empty pans and 

sapphire 

�Measure sample mass, e.g., 14.20 mg 

�Measure Heat Flow at 380K, e.g., 4.60 mW 

�Substitute E into equation on page 103. 

Cp = 

E 

H 

(1.06) x (4.60 mW (mJ/sec)) x (60 sec/min) 

(20°C/min) x (14.20 mg) 

Hr 

M 

Cp = 1.030 mJ/mg/°C (J/g/°C) 

DSC: What Affects the Specific Heat 

Capacity? 

�Amorphous Content 

�Aging 

�Side Chains 

�Polymer Backbone 

�Copolymer Composition

DSC: 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. 

DSC: Effect of Annealing 

(Crystallization) on Cp of PEEK 

Complex Cp (J/g/°C) 

2.2 

2.0 

1.8 

1.6 

1.4 

Amorphous PEEK 

PEEK annealed at 300°C 

PEEK annealed at 330°C 

1.2 

100 110 120 130 140 150 160

DSC: Effect of Aging on the Specific 

Heat Capacity of Polystyrene 

Endotherm 

406 

272 

240 

120 

360 380 400 420 

Temperature (K) 

DSC: Effect of Side Chains on Specific 

Heat Capacity 

tg (h) 

Polymer Side Chain Cp (J/g/°C) 

PE -H 2.763 

PP -CH 2.752 

PS -Ph 2.139 

As the steric bulk of the side chain increases, molecular 

mobility decreases resulting in lower specific heat. 

66 

24 

3 

0

DSC: Effect of Polymer Backbone on Specific 

Heat Capacity of Polyoxyalkenes @ -153°C 

O 

O 

( CH2n ) 

[ ] 

# of Methylenes Cp (J/g/°C) 

1 0.6226 

2 0.6918 

3 0.7088 

4 0.7597 

8 0.7736 

As the number of methylenes increase, mobility is 

increased in the polymer, resulting in higher heat capacity. 

B. Wunderlich, ATHAS Cp Data Bank, 1985. 

DSC: Effect of Copolymer Composition on Specific 

Heat Capacity of PE/PP Copolymer @ -93°C 

Composition Copolymer Cp 

(%PP) (Type) (J/°C/mol) 

6.0 block 15.12 

7.5 random 16.39 

15.5 random 18.54 

As PP concentration is increase, the number of methylenes 

increases, resulting in a rise in specific heat capacity. Also, with 

randomness comes entropy, increase in mobility, and increase 

in specific heat capacity.

DSC: Modulated DSC TM 

�Theory 

�Signals 

�Applications 

�Experimental Conditions 

�Calibration 

MDSC Theory


Heat Flow Equation 

dH 

dt 

dH 

dt 

= Cp 

dT 

dt 

+ 

f ( T, 

t) 

= Total Heat Flow measured 

by the calorimeter 

Cp = Specific Heat Capacity 

dT 

dt 

= Underlying Heating Rate 

f(T,t) = kinetic response of sample 

Heat Flow Due to Heat Capacity 

0 

(2) 

(4) 

(6) 

(8) 

(10) 

40 

60 

80 

106.85°C 

-2.137mW 

106.85°C 

-4.018mW 

106.85°C 

-8.104mW 

100 

120 

140 

5°C/min 

10°C/min 

20°C/min 

160 

180 

200

Heat Flow 

Heat Flow 

Kinetic Heat Flow 

Isothermal Temperature 

The magnitude of measured kinetic 

heat flow is a function of time at a 

constant temperature. 

0 t 1 

t2 

time 

Standard DSC Measures the Sum of Heat Flow 

Heat Flow due to 

Heat Capacity 


Kinetic Events

Heat Flow 

Heat Flow Can Be Separated 

f(T,t) 


Kinetic Events 

Cp dT 

dt 


Heat Capacity 

Temperature 

General Theory of MDSC 

Heat flow from DSC experiments is composed of two parts 

but DSC can only measure the sum of the two. 

dH/dt = Cp (dT/dt) + f (T,t) 

Total = Heat Capacity + Kinetic 

Heat Flow Component Component 

(DSC) 

= Heating Rate + Time 

Dependent Dependent 

= MDSC Reversing + MDSC Nonreversing

Distribution of Transitions in MDSC Experiments 

Total = Heat Capacity + Kinetic 

Component Component 

= Reversing Heat Flow + Nonreversing Heat Flow 

glass transition 

melting (some) 

Physical Measurement Technique 

enthalpic relaxation 

evaporation 

crystallization 

decomposition 

cure 

melting (some) 

Apply Stimulus Measure Response 

Stimulus Response 

FTIR IR Radiation Absorbance 

Wavelength 

NMR Magnetic Field Resonance 

Frequency 

X-Ray Diffraction X-Ray Radiation Angle of 

Diffraction 

MDSC Sinusoidal 

Heating Rate 

Amplitude of 

Heat Flow

Deriv. Modulated Temp (°C/min) 

Raw Signals in MDSC 

All Modulated DSC Signals are derived from 

three measured parameters. 

8 

6 

4 

2 

0 

Time 

Modulated Temperature (Stimulus) 

Modulated Heat Flow (Response) 

MDSC Raw Signal 

COLD CRYSTALLIZATION 

MODULATED HEAT FLOW 

(Response) 

CRYSTALLIZATION DURING MELTING 

GLASS TRANSITION 

MODULATED HEATING RATE 

(Stimulus) 

NOTE: ALL TRANSITIONS OF 

INTEREST ARE CONTAINED IN 

MDSC RAW DATA SIGNALS 

MELTING 

50 100 150 200 250 300 

0.2 

0.0 

-0.2 

-0.4 

-0.6 

Modulated Heat Flow (W/g)


Temperature Change (MDSC) 

240 

230 

220 

210 

ACTUAL MEASURED TEMPERATURE 

200 

200 

38 39 40 41 42 43 44 45 

Exo Up Time (min) 

Universal V2.5D TA Instruments 

MDSC Signals: Total Heat Flow 

CALCULATED AVERAGE 

TEMPERATURE 

The average value of the modulated heat flow signal. This 

signal is qualitatively and quantitatively equivalent to the heat 

flow signal from conventional DSC at the same average 

heating rate. 

Definition: The sum of all thermal events in the sample 

Calculation: Fourier Transformation analysis of the modulated 

heat flow signal is used to continuously calculate its average 

value 

P 

A 

240 

230 

220 

210 

Modulated Temp (°C)

Modulated Heat Flow (W/g) 

Total Heat Flow: Average of Modulated Heat 

Flow Signal 

0.2 

0.1 

0.0 

-0.1 

-0.2 

-0.3 

-0.4 

0.2 

0.0 

-0.2 

-0.4 

50 100 150 200 250 300 


MDSC Signals: Heat Capacity 

A 

Cp = 

A 

MHF 

K 

MHR 

Where: 

AMHF = Amplitude of Modulated Heat Flow 

AMHR = Amplitude of Modulated Heating Rate 

K = Heat Capacity Calibration Factor 

Definition: The amount of heat required to raise the 

temperature of a material 1°C. 

Calculation: The basis for making the heat capacity 

measurement in MDSC can be explained from a series of 

x 

Heat Flow (W/g)

Conventional DSC Cp Measurement 

Cp = K x 

HFS 

– HFMT 

Heat Rate x wt 

Where: 

K = Calibration constant 

HFS = Differential heat flow 

with sample 

HFMT = Differential heat flow 

with empty pans 

wt = weight of sample 

0 

HF 

� 

endo 

Alternative DSC Cp Measurement 

Cp 

= 

K x 

HF 

(HR 

HR2 

2 

– HF 

– HR1) 

HR1 

wt 

Where: 

K = Calibration constant 

HFHR1 = Differential heat flow of 

sample at HR1 HFHR2 = Differential heat flow of 

sample at HR2 HR2 = Heating rate 2 

= Heating rate 1 

HR 1 

0 

HF 

� 

endo 

HF MT 

HF S 

Temp. 

Temp. 

HF HR1 

HF HR2

Heat Capacity from MDSC Raw Signals 

Deriv. Modulated Temp (°C/min) 

10 

5 

0 

MODULATED HEAT FLOW 

HEAT CAPACITY 

MODULATED HEATING RATE 


0.6 

0.2 

-0.2 

50 100 150 200 250 

-0.6 

300 

Temperature 

(°C) 

MDSC Signals - Reversing Heat Flow 

(Heat Capacity Component) 

Reversing Heat Flow is the heat capacity component of the total heat flow. It is 

calculated by converting the measured heat capacity into a heat flow signal using 

the classical heat flow equation as a theoretical basis. 

Reversing Heat Flow = –Cp x Avg. Heat Rate 

Basis for Calculation 

Where : 

dH 

= 

total heat flow 

dt 

Cp = measured heat capacity 

dH 

dt 

= Cp 

dT 

= average heating rate 

dt 

dT 

Cp = heat capacity component (Reversing) 

dT 

dt 

+ 

f 

6 

4 

2 

0 

2 

4 

(T, t) 

Modulated Heat Flow (W/g)

Reversing Heat Flow from MDSC Raw Signals 



8 

4 

0 

-4 

-8 

HEAT CAPACITY 

REVERSING HEAT FLOW 

50 100 150 200 250 300 


0.15 

0.05 

-0.05 

-0.15 

-0.25 

Quench Cooled PET: Total vs. Reversing Heat 

Flow 

0.1 

0.0 

-0.1 

-0.2 

-0.3 

TOTAL 

REVERSING 

-0.25 

50 100 150 200 250 300 

Rev Heat Flow (W/g) 

0.15 

0.05 

-0.05 

-0.15 

[ ]Rev Heat Flow (W/g)

MDSC Signals - Nonreversing Heat Flow 

(Kinetic Component) 

Nonreversing Heat Flow is the kinetic component of the total heat 

flow. It is calculated by subtracting the heat capacity component from the 

total heat flow using the classical heat flow equation as a theoretical basis. 

Nonreversing = Total – Reversing 

Basis for Calculation 

dH dT 

= Cp + f (T, t) 

dt dt 

dH 

= total heat flow 

dt 

dT 

Cp = heat capacity component (reversing) 

dt 

f (T, t) = kinetic component (nonreversing) 

Quench-Cooled PET: Deconvoluted Signals 


0.25 

0.15 

0.05 

-0.05 

-0.15 

-0.25 

NONREVERSING 

TOTAL 

REVERSING 

0.25 

0.15 

0.05 

-0.05 

-0.15 

-0.25 

50 100 150 200 250 300 

Nonrev Heat Flow (W/g) 

0.1 

0.0 

-0.1 

-0.2 

Rev Heat Flow (W/g)

Glass Transition of Polymer Resin 

MDSC: Glass Transition of Epoxy Coating 


-0.20 

-0.22 

-0.24 

-0.26 

-0.28 

-0.30 

NOTE: Sensitivity is 100µW Full Scale 

TOTAL 

REVERSING 

0.00 

-0.02 

-0.04 

-0.06 

-0.08 

0 20 40 60 80 100 120 

-0.10 

140 

Rev Heat Flow (mW)

PET/ABS Blend - Conventional DSC 


-0.2 

-0.3 

-0.4 

-0.5 

-0.6 

-0.7 

-0.8 

120.92°C 

67.38°C 

70.262°C (H) 

111.82°C 

9.016J/g 

first heat on molded part 

second heat after 10°C/min cooling 

(Curve shifted on Y axis to avoid overlap) 

9.22 mg sample, nitrogen purge 

10°C/minute heating rate 

235.36°C 

22.63J/g 

249.75°C 

50 100 150 200 250 


PET/ABS - MDSC 


-0.10 

-0.11 

-0.12 

-0.13 

-0.14 

-0.15 

first heat on molded part 

PET Tg 

67.00°C 

+72.89°C (H) 

104.45°C 

107.25°C (H) 

8.46mg sample ABS Tg 

nitrogen purge 

2°C/minute heating rate, ±1°C amplitude, 60 second period 

20 40 60 80 100 120 140 160 

( ) Nonrev. Heat Flow (W/g) 

-0.02 

-0.03 

-0.04 

-0.05 

-0.06 

-0.04 

-0.05 

-0.06 

-0.07 

-0.08 

-0.09 

180 200 

( ) Rev. Heat Flow (W/g)

MDSC: Detection of Two Glass 

Transitions in PC/PEE Blend 

Rev Heat Flow (W/g) 

-0.02 

-0.04 

-0.06 

-0.08 

-0.10 

3 CONSECUTIVE HEATING RUNS AFTER 2deg/min COOLING 

+ 

62. 58° C 

DERIVATIVE 

-0.001 

-0.002 

-0.003 

-0.004 

-0.12 NOTE 81°C WIDTH OF GLASS TRANSITION 

-0.005 

40 60 80 100 120 140 160 


3 

2 

1 

+ 

141. 45° C 

MDSC ±0.424°C, 40 sec. period 

4°C/min underlying ramp rate 

MDSC: Heat Capacity for PET During 

Isothermal Steps 


1.6 

1.4 

1.2 

PLOT vs TIME 

Heat Capacity 

Temperature 


1°C isothermal steps 

1.0 

60 

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 

140 

120 

100 

80 


Deriv. Rev Heat Flow (W/g/min)

MDSC: PET Heat Capacity During Glass 

Transition & Cold Crystallization 


1.6 

1.5 

1.4 

1.3 

1.2 

1.1 

GLASS TRANSITION 

(Second-Order Transition) 

60 70 80 90 100 110 120 130 

Isothermal Epoxy Cure 

Nonrev. Heat Flow (mW) 

6 

4 

2 

0 

Isothermal 80°C 

helium purge 

±0.5°C amplltude 

60 second period 

Heat 

Capacity 


∆H of Cure 

COLD CRYSTALLIZATION 

(First-Order Transition) 


1°C isothermal steps 

DMA 1Hz 

( ) E' (GPa) 

30 

20 

10 

0 

14.5 

14.0 

13.5 

13.0 

12.5 

12.0 

11.5 

( ) Heat Capacity (mJ/°C)

MDSC: Heat Capacity vs. Cure Time 

TM = 

Epoxy-Amine System MDSC Result at 70°C Cure 

( ) Nonreversing Heat Flow (mW/g) 

120 

90 

60 

30 

Heat Capacity 

exo 

t1/2∆Cp t1/2∆Cp X = 0.53 

0 

1.0 

0 100 200 300 

Time (min) 

= 

Thermochimica Acta, 268, 121-142 (1995), Dr. B. Van Mele, et al 

at Vrije Universiteit Brussels (Belgium) 

vit 

Nonreversing Heat Flow 

=97 mi 

MDSC: Experimental Considerations 

Modulation Period? 

Calibration? 

Phase Correction? 

2.5 

2.0 

1.5 

( ) Heat Capacity (J/g/K) 

Sample Dimensions? 

Purge Gas?

MDSC: Sample Preparation 

�Thin, Low Mass Samples 

�Minimize Thermal Gradients 

�Allow for Faster Periods, Larger 

Modulation Amplitudes 

�Thicker, Heavier Samples 

�Minimize Baseline Curvature 

�Improve Sensitivity 

MDSC: Sample Pans 

Standard Crimped 

�Low, Consistent Mass 

�Best Choice for MDSC Measurements 

�Solids, Powders, Films 

�Volatility may be an issue

MDSC: Sample Pans 

Standard Hermetic 

�Use for liquid/volatile samples 

�Higher Mass, Less Sensitivity 

�Use Heat Sink Compound 

MDSC: Purge Gas 

�Nitrogen 

�Economical 

�Wide Operating Range 

�Provides Good Sensitivity 

�Helium 

�Higher Thermal Conductivity 

�Facilitates Wider Range of Modulation 

Conditions

MDSC: Purge Gas Flow Rates 

�Use Purge Gas Flow Rate of 50 mL/min. (N2) & 

25 ml/min (He) 

�Faster rates increase noise 

�Slower rates decrease sensitivity, increase 

baseline curvature 

�Flow Purge Gas through Vacuum Port 

at 50 mL/min. 

�Improves response of furnace 

�Facilitates wider range of modulation 

parameters 

MDSC: Baseline Calibration 

Identical to Standard 

DSC experiment 

Eliminates Baseline 

Drift 

Does not affect 

curvature 

-Slower heating rates 

contribute to 

curvature 

-Heavier sample 

masses minimize 

< 

Delta µ ( V) 

Baseline Calibration - 2920 MDSC (4) 

Sample: Empty Pans DSC File: D:\TA\DSC\...BASE1102.001 

-4 

-6 

-8 

Baseline Calibration 

Slope: -0.0005 

Offset: -8.564 

Cell Number: 319 

-90.29°C 

287.04°C 

-10 

-200 -100 0 100 200 300 400 

Temperature (°C)

MDSC: Heat Flow (Cell Constant) 

Calibration 


v 

Identical to Standard DSC Calibration 

Baseline Calibration - 2920 MDSC (4) 

Sample: Indium Metal DSC File: D:\TA\DSC\DATA\CAL0512.001 

0 

-5 

-10 

-15 

-20 

157.74°C 

Cell Constant Calibration 

Indium Standard Heat: 28.71 J/g 

Cell Constant: 1.5555 

Onset Slope: -40.63 mW/°C 

Cell Number: 319 

-25 

150 152 154 156 158 160 162 164 


MDSC: Cell Constant Effect on 

Modulated Heat Flow 

Modulated Heat Flow (mW) 

4 

2 

0 

-2 

E = 0.5 

E = 1.0 

E = 1.6 

-4 

25 75 125 175 225 275 

Temperature (°C)

K(Cp) 

MDSC: Heat Capacity Calibration 

�Provides for Accurate Heat Capacity Measurements 

�Use Either Sapphire Disc (wide temperature range) or 

HDPE (polymer melt) 

�Choose one-point or average values 

�Effects of Experimental Conditions 

MDSC: Heat Capacity Calibration- 

Frequency Dependence 

1.3 

1.2 

1.1 

1 

0.9 

0.8 

10 Sec 

20 Sec 

30 Sec 

40 Sec 

50 Sec 

60 Sec 

70 Sec 

80 Sec 

90 Sec 

100 Sec

K(Cp) 

K(Cp) 


Frequency Dependence (cont.) 

0.95 

0.93 

0.91 

0.89 

0.87 

0.85 

40 Sec 

50 Sec 

60 Sec 

70 Sec 

80 Sec 

90 Sec 

100 Sec 

0 10 20 30 40 50 60 70 80 90 100 



Amplitude Dependence 

0.94 

0.93 

0.92 

0.91 

0.9 

0.89 

0.88 

0.87 

0.86 

0.85 

0.10°C 

0.25°C 

0.50°C 

0.75°C 

1.00°C 

1.25°C 

1.50°C 

1.75°C 

2.00°C

K(Cp) 

MDSC: Heat Capacity Calibration - 

Heating Rate Dependence 

0.94 

0.92 

0.9 

0.88 

0.86 

0.84 

0 10 20 30 40 50 60 70 80 90 100 


1°C/min 

3°C/min 

5°C/min 

Isothermal 

Effect of Modulation Conditions on K 

K 

1.60 

1.50 

1.40 

1.30 

1.20 

1.10 

1.00 

10 20 30 40 50 

Period (sec) 

60 70 80 90 100 

0.1 

0.2 

He purge @ 25 ml/min. 

1 

0.8 

0.4 

1.6 

1.4 

1.2 

1.82 

Amplitude (±°C)

Differential Scanning Calorimetry (DSC)

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