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Theory and Experimental ConditionsGlass TransitionMelting and CrystallizationHeat CapacityMDSC
Differential ScanningCalorimetry (DSC)
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.
DSC: The Technique
TA Instruments DSC’s
DSC 2010 DSC 2910 DSC 2920
DSC: What DSC Can Tell You
Glass TransitionsMelting and Boiling PointsCrystallization time and temperaturePercent CrystallinityHeats of Fusion and ReactionsSpecific HeatOxidative/Thermal StabilityRate and Degree of CureReaction KineticsPurity
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 ∆Tor in differential form
dH/dt = Cp dT/dt + thermal eventswhere:
Cp = specific heat (J/g°C)T = temperature (°C)H = heat (J)dH/dt = heat flow (J/min.)mW = mJ/secdT/dt = heating rate (°C/min.)
assuming work & mass loss are zero
DSC: Measurement of HF and T
Sample Ref
chromel alumel
constantanCu-Ni
Ni-Cr Ni-Al
Platinel ControlThermocouple
Ag furnace
DSC: Temperature Measurement
Sample Temperature Ts
Sample Ref
FurnaceTemperature
Tc
DSC: Heat Flow Measurement
Sample Ref
Potential Difference ∆UTemperature Difference ∆T
Heat Flow dQ/dt
Alumel wire (sample temp)
Chromel wires (∆T)
DSC: Cell Schematic DiagramDynamic Sample Chamber
Reference PanSample Pan
Lid
Gas Purge Inlet
Chromel Disc
Heating Block
Chromel Disc
Alumel Wire
Chromel Wire
Thermocouple Junction
Thermoelectric Disc (Constantan)
DSC: Cell Components
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 ( ) between the sample andreference is converted to differential heat flow in a way thatis analogous to current flow in Ohms Law.
I = E/R where: I = currentE = voltage (potential)R = electrical resistance
∆ T
THeat Flow =R
k1 k2 where:
T = temperature difference (potential)R = thermal resistance of constantan disk
k1 = factory-set calibration valuek2 = 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 ∆Ubetween the sample and reference constantan/chromeljunctions. The voltage is adjusted for thermocouple response S and is proportional to heat flow.
∆T = ∆U / S ∆T in °C∆U in µVS 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
(TAI DTA: up to 1600°C <-> TAI DSC: up to 725°C)
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 SignalsTimeTemperatureHeat Flow
Signal Change Properties MeasuredHeat Flow, absolute Specific HeatHeat Flow, shift Glass TransitionExothermic Peak Crystallization or CureEndothermic Peak MeltingIsothermal Onset Oxidative Stability
DSC: Typical DSC Transitions
Temperature
Hea
t Flo
w -
> e
xoth
erm
ic
GlassTransition
Crystallization
Melting
Cross-Linking(Cure)
Oxidation or
Decomposition
Available Method Segments
Method Design Rules
Typical Methods (Examples)
DSC: Experimental Design
DSC: Available Method Segments
JUMP ABORT NEXT SEG*EQUILIBRATE SAMPLING INTERVALINITIAL TEMPERATURE SELECT GASRAMP EXTERNAL EVENTISOTHERMAL DATA STORAGEISO-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 TemperatureGenerally, 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 TemperatureAllow 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 ifstarting at or near ambient temperature.)1) Ramp 10°C/min. to 300°C
Cooling Method1) Equilibrate at 300°C2) Ramp 10°C/min. to 25°C
DSC: Heat-Cool-Reheat Method
Heat-Cool-Reheat Method
1) LNCA control: High2) Ramp 10°C/min. to 300°C3) Mark cycle end 04) Ramp 10°C/min. to 25°C5) Mark cycle end 06) Ramp 10°C/min. to 300°C7) Mark cycle end 0
The first segment in this method allows for rapid coolingafter Segment 2 is complete.
DSC: Oxidative Stability (OIT) Method
OIT Method
1) Equilibrate at 60°C2) Isothermal for 5.00 min.3) Ramp 20°C/min. to 200°C4) Isothermal for 5.00 min.5) Abort next seg. if W/g > 1.06) Select gas: 27) Iso-track for 200.00 min.
DSC: Modulated DSC Method
MDSC Method
1) Data storage: off2) Equilibrate at -20°C3) Modulate ±1°C every 60 seconds4) Isothermal for 5.00 min.5) Data storage: on6) Ramp 3°C/min. to 300°C
DSC: Calibration & Sample Preparation
Instrument CalibrationDifferential Heat Flow (Cell Constant)TemperatureBaseline
MiscellaneousPurge GasCooling AccessoriesEnvironment
Sample PreparationSelecting Experimental ConditionsRoutine Maintenance/Sample Press
DSC: Heat Flow Calibration
Differential Heat Flow (ASTM E968)Heat of fusion (melting) standardsHeat capacity (no transition)
MiscellaneousUse specific purge gas at specified rateCalibrate w/cooling accessory functioning if it will be used to run samplesSingle point used for heat of fusion which is typically accurate to +/- 1-2% from -50°C to 350°CCalibration should not change w/heating rate
DSC: Heat Flow Calibration
Prepare a 10 to 15 mg. sample of indium and premeltprior 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
150 155 160 165 170-15
-10
-5
0
5
Temperature (°C)
Hea
t F
low
(m
W)
157.44°C
Sample: Indium, 5.95 mg.CALIBRATION MODE; 10°C/MINCALIBRATION BASED ON 28.42J/g
Cell Const.: 1.0766Onset Slope: -20.82 mW/°C
DSC: Temperature Calibration
ASTM Method E967Pure metals (indium, lead, etc.) typically usedExtrapolated onset is used as melting temperatureSample is fully melted at the peak
MiscellaneousWith metal standards, calibration should change very little with heating rate
With metal standards, it is not practical to calibrate forchanges in heating rate on polymer samples
DSC: Temperature Calibration
150 152 154 156 158 160 162 164-5
-4
-3
-2
-1
0
1
0
10
20
30
40
50
Temperature (°C)
Hea
t F
low
(W
/g)
Der
iv. T
emp
erat
ure
(°C
/min
)Extrapolated Onset
156.61°C28.36J/g
HEATING RATE
157.09°CPEAK
DSC: Temperature Calibration
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
Benzoic acid (147.3 J/g) Tm = 123°CUrea (241.8 J/g) Tm = 133°C Indium (28.45 J/g) Tm = 156.6°CAnthracene (161.9 J/g) Tm = 216°C
Cyclopentane* -150.77°CCyclopentane* -135.09°CCyclopentane* -93.43°CCyclohexane# -83°CWater# 0°CGallium# 29.76°CPhenyl Ether# 30°Cp-Nitrotoluene 51.45°CNaphthalene 80.25°CIndium# 156.60°CTin# 231.95°CLead* 327.46°CZinc# 419.53°C
DSC: Recommended Temperature &Enthalpy Standards
* GEFTA recommendedThermochim. Acta, 219 (1993) 333.
# ITS 90 Fixed Point
Zone refined organic compound(sublimes)
Enthalpy(cell constant)
Temperature
DSC: Traceable Calibration Materials
NIST DSC calibration materials:SRM 2232 Indium Tm = 156.5985°CSRM 2220 Tin Tm = 231.95°CSRM 2222 Biphenyl Tm = 69.41°CSRM 2225 Mercury Tm = -38.70°CSRM 2221b Zinc Tm = In Preparation
NIST: Gaithersburg, MD 20899-0001Phone: 301-975-6776Fax: 301-948-3730Email: [email protected]: HTTP://ts.nist.gov/srm
DSC: Traceable Calibration Materials
LGC DSC Calibration Materials:LGC2601: Indium (TA p/n: 915060-901)LGC2608: LeadLGC2609: TinLGC2611: Zinc
Laboratory of the Government Chemist, UKPhone: 44 (0) 181 943 7565Fax: 44 (0) 181 943 7554Email: [email protected]
DSC: Traceable Calibration Materials
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 materialsCertificate of Calibration issued showing traceability of calibration to a national laboratory
DSC: Effect of Heating Rateon Indium Melting Temperature
154 156 158 160 162 164 166 168 170-5
-4
-3
-2
-1
0
1
Temperature (°C)
Heat Flow (W/g)
Heating Rates = 2, 5, 10, & 20°C/min
DSC: Effect of Heating Rateon Indium Melting Temperature
Heat Rate Onset Peak ∆HOnset
Variationto 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/InternalTemperature Calibration Material
2 Layersof Polymer
Film
Melting PointStandard, e.g.
Indium
Typical weight of polymer sample is 10mg(2 films at 5mg each) with 1-3mg of Indium
DSC: Indium Sample Placed BetweenTwo HDPE Film Samples
PolyethyleneMelt
IndiumMelt
20 40 60 80 100 120 140 160 180-6
-4
-2
0
Temperature (°C)
Heat Flow (W/g)
Sample: Linear Polyethylene-IndiumSize: 10.0000 mg Operator: LabMethod: VarHeat Run Date: 11-Jun-97 12:43Comment: DSC @ 2,5,10%20°C/min; crimped pans, HS Cmpd
DSC
DSC: Effect of Heating Rate on HDPEand Indium Melting
PolyethyleneMelt
IndiumMelt
20 40 60 80 100 120 140 160 180-8
-6
-4
-2
0
Temperature (°C)
Heat Flow (W/g)
DSC: Effect of Heating Rate on Indium Melting When Placed Between Polymer Films
154 156 158 160 162 164 166 168 170
-2.0
-1.5
-1.0
-0.5
0.0
0.5
Temperature (°C)
Heat Flow (W/g)
Heating Rates = 2, 5, 10 & 20°C/min
DSC: Effect of Heating Rate on Indium MeltingWhen Placed Between Polymer Film
Heating RateStandardSample
Polymer SandwichSample
2°C/min -0.12°C +.03°C
5 -0.07 +.16
10 0 +0.44
20 +0.15 +0.82
Onset Variation When Calibrated at 10°C/min.
DSC: Baseline Calibration
SlopeCalibration should provide flat baseline with empty pansPolymers should always have an endothermicslope due to increasing heat capacity withincreasing temperature
CurvatureNot normally part of calibration procedureCan be eliminated if necessary with baselinesubtractionCurvature can cause errors in analyses
DSC: Baseline Slope
20 40 60 80 100 120 140 160 180 200-2.0
-1.5
-1.0
-0.5
0.0
0.5
Temperature (°C)
Hea
t F
low
(W
/g)
Empty Pans
10 mg Polystyrene
DSC: Baseline Curvature
100 150 200 250 300 350-0.2
-0.1
0.0
0.1
-0.2
0.0
0.2
0.4
Temperature (°C)
Hea
t F
low
(W
/g)
Hea
t F
low
(W
/g)
Heating @ 1°C/min
Heating @ 3.5°C/min
SDT 2960 Calibration
•DTA Baseline and empty beams
TGA Weight Calibration calibration weights
•Temperature Calibration up to 5 temperature
standards
•DSC Heat Flow Calibration sapphire
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 GasType of purge gas and flow rate affect calibration and therefore
should be controlledNitrogen is preferred because it is inert and calibration is least
affected by changes in flow rate
Cooling AccessoriesIf used, they should be operating and equilibriated prior to
calibration or sample runs
Warm-up Time/EnvironmentElectronics should be given at least one hour to stabilize for
important samples if the instrument has been turned OFFElectronics are effected by ambient temperature. Avoid areas such
as hoods or near an air conditioner
DSC: Recommended Purge Gas FlowRates & Effect of Flow Rate
Purge Port (mL/min.)
Module Purge Cool VacuumDSC 2920/2910/2010 50 (N ) 50*
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
2
DSC: Effect of Flow Rate on Cell Constant
1.00
1.10
1.20
1.30
1.40
1.50
1.60
1.70
1.80
0 10 20 30 40 50 60 70 80 90 100 110
Purge Gas Flow Rate
Cel
l Con
stan
t
Nitrogen Cell Constant
Helium Cell Constant
DSC: Sample Preparation
Sample WeightSelection 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 bein the range of 0.1 - 10mW
- metal or chemical melting: <5mg- polymer Tg or melting: 10mg- composites or blends: >10mg
The accuracy of the analytical balance- sample weight should be accurate to +1%
DSC: Heat Flow Change During aTransition
+
40 60 80 100 120 140 160 180 200 220-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
Temperature (°C)
Heat Flow (mW)
161.17°C1.593mW
69.41°C
73.37°C(H)0.4881mW
143.70°C34.95J/g
DSC: Sample Preparation (cont.)
Sample ShapeKeep sample as thin as possible and cover as much of the pan bottom as possibleSamples should be cut rather than crushed to obtain a thin sampleLids should be used with sample pans in order to keep the sample in contact with the bottom of the pan
Sample PansUse lightest, flattest pan possibleUse 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 Weighton DSC Baseline
REFERENCE PAN WITH 2 LIDS1.688mW
REFERENCE PAN WITH 1.5 LIDS
REFERENCE PAN WITH LID
NO REFERENCE PAN
-0.6018mW
-1.953mW
-10.04mW
90 110 130 150 170-12
-10
-8
-6
-4
-2
0
2
4
Temperature °C
Hea
t F
low
(m
W)
Sample: EpoxyWeight: Approx. 10mgHeat Rate: 20°C
DSC: Comparison of DSC Tg Using No ReferencePan and One of Equal Cp to Sample
90 110 130 150 170-0.8
-0.6
-0.4
-0.2
0
0.2
Temperature (°C)
Hea
t F
low
(m
W)
Cp REF = Cp SAMPLE
NO REFERENCE
DSC: Experimental Conditions
Heating/Cooling RatesHigh rates increase sensitivity
Low rates increase resolution by providing more time at any temperature
Purge Gasnitrogen increases sensitivity because it is a relatively poor thermal conductorhelium increases resolution because it is a good conductor of heat to or from the sample
dQ
dt = Cp x
dT
dt + (T, t)f
heat flowmeasuredby DSC
= heat capacityor weightof sample
x heatingrate
+ time dependentor kineticcomponent
DSC: Experimental Conditions
General Summary
ConditionTo IncreaseSensitivity
To IncreaseResolution
Sample Size Increase Decrease
Heat Rate Increase Decrease
Ref Pan Weight Increase No Effect
Purge Gas Nitrogen* Helium*
*instrument should be calibrated with the samepurge gas as used to run a sample
DSC: Sample Pan Types
Pan TypeAluminumCopperGoldGraphiteAl HermeticAl Alodined HermeticGold HermeticHigh Volume (100µL)Al Solid Fat Index (SFI)Platinum
Upper Temp Limit600°C725°C (in N2)725°C725°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)
DSC: Sample Pan SelectionStandard Aluminum Pans
Use a thin layer
Distribute materialevenly
DSC: Sample Preparation – Hermetic Pans
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 hermeticliquid Tn,Tc,Tg,Tm hermetic, SFI, open
Cp hermeticOIT SFI, open
aqueous solution Cp,Tm,Tg alodined or goldhermetic
foods/biologicals denaturation high volume (100µL)
DSC: Sample Pan Selection
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°CIsothermal for 10 min.Cool cell to room temperatureBrush out cell with fiberglass brushCheck for improved baseline performance
NEVER use solvents to clean DSC cell
Thermoplastic Polymers
Semi-Crystalline (or Amorphous)
Crystalline Phasemelting temperature Tm(endothermic peak)
Amorphous Phaseglass transition temperature (Tg)(causing ∆Cp)
Tg < TmCrystallizable polymer can crystallize
on cooling from the melt at Tc(Tg < Tc < Tm)
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 crystallizationproperties 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 20 40 60 80-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0
50
100
150
200
250
300
Time (min)
Hea
t F
low
(W
/g)
[
] T
emp
erat
ure
(°C
)First Heat Cooling
SecondHeat
DSC: Thermoplastic: Heat Flow vs.Temperature for Heat/Cool/Heat
20 40 60 80 100 120 140 160 180 200 220 240 260 280-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
Temperature (°C)
Hea
t F
low
(W
/g)
Second HeatFirst Heat
Cool
191.41°C
223.01°C48.03J/g
DSC: Selecting Experimental Conditions
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 inmaterial, thermal history or both
If the materials are different then there will be differences in the Cool and Second Heat resultsIf the materials are the same and they have had the same thermal history then all three (H-C-H) segments will be similarIf 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
Thermosetting polymers react (cross-link) irreversibly. A+B will give out heat (exothermic) when they cross-link (cure). After cooling and reheating C will have only a glass transition Tg.
A + B C
GLUE
DSC: Selecting Experimental Conditions
Thermosetting PolymersAnneal 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 TgFirst Heat is used to measure Tg and residual cure (unreactedresin). Stop at a temperature below the onset of decompositionCooling segment gives the sample a known thermal historySecond 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 Shapeof the Glass Transition
0 10 20 30 40 50 60 70 80 90 100-0.4
-0.3
-0.2
-0.1
0.0
-0.2
0.0
0.2
0.4
Temperature (°C)
Hea
t F
low
(W
/g)
Hea
t F
low
(W
/g)
annealed
aged
DSC: Thermoset: Comparison of Firstand Second Heating Runs
0 50 100 150 200 250 300-0.24
-0.20
-0.16
-0.12
-0.08
-0.04
Temperature (°C)
He
at
Flo
w (
W/g
)
Tg
Tg
155.93°C
102.64°C20.38J/g
Residual Cure
First
Second
DSC: Determination of % Cure
79.33J/g75.21 % cured
NOTE: Curves rescaled and shifted for readability
145.4J/g54.55 % cured
Under-cured Sample
Optimally-cured Sample-5.27°C(H)
DSC Conditions:Heating Rate = 10°C/min.Temperature Range = -50°C to 250°CN2 Purge = 50mL/min.
-12.61°C(H)
-0.5
0.0
0.5
1.0
1.5
2.0
He
at F
low
(W
/g)
-50 0 50 100 150 200 250
Temperature (°C)Exo Up Universal V2.4F TA Instruments
DSC: Characterization of Epoxy Prepreg
What is it?
How is it observed and measured?
What affects the Glass Transition?
DSC: The Glass Transition (Tg)
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 DecreasesCoefficient of thermal expansion
Increases
Specific Heat IncreasesEnthalpy IncreasesEntropy Increases Temperature
V,1/E,
CTE
CpH &S
Tg
DSC: Measurements of the Tg
TEMPERATURE (°C)
en
do
HE
AT
FL
OW
exo
To Tf
TmTi Te Tr
T = Temperature of First Deviation ( C)
T = Extrapolated Onset Temperature ( C)
T = Midpoint Temperature ( C)
T = Inflection Temperature ( C)
T = Extrapolated Endset Temperature ( C)
T = Temperature of Return-to-Baseline ( C)
oo
fo
mo
io
eo
ro
1/2h
1/2h
DSC: Polyethylene TerephthalateGlass Transition
40 60 80 100 120-1.0
-0.9
-0.8
-0.7
-0.6
Temperature (°C)
Hea
t F
low
(m
W)
71. 54° C
0. 3005mW
79. 88° C
DSC: What Affects the Glass Transition?
Heating Rate Crystalline ContentHeating & Cooling CopolymersAging Side ChainsMolecular Weight Polymer BackbonePlasticizer Hydrogen BondingFiller
DSC: Heating Rate
Heating Rate Sensitivity Reproducibility(°C/min)
5 poor very good20* good good40 very good poor
* Recommended heating rate for measuring Tg.
DSC: Heating/Cooling of Polystyrene
75 80 85 90 95 100 105 110 115-0.10
-0.05
0.00
0.05
0.10
0.15
Temperature (°C)
DS
C H
eat
Flo
w (
W/g
) 10 °C/min COOLING
10 °C/min HEATING
MDSC: Heating/Cooling of Polystyrene
75 80 85 90 95 100 105 110 1150.50
0.60
0.70
0.80
0.90
1.00
Temperature (°C)
Hea
t C
apac
ity
(J/g
/°C
)
5 °C/min COOLING
5 °C/min HEATING
Effect of Cooling Rate on Tg
increased amorphousfraction
Quench
20
10
0.2
Heat Capacity MeasuredAfter Cooling at Quench,20, 10, 5, 2, 1 and 0.2°C/min
20 40 60 80 100 120 140 160
1.0
1.2
1.4
1.6
1.8
2.0
Temperature (°C)
Hea
t C
apac
ity
(J/g
°C)
DSC: Effect of Aging on the GlassTransition [M. Todoki, Polymer Data Handbook]
0 50 100 150Temperature (°C)
Glass Transition
Cold Crystallization
As-Spun
2 days
28 days
196 days
3 years and2 months
4 years and11 months
DSC: Effect of Annealing on Polystyrene
40 60 80 100 120 140 160-0.3
-0.2
-0.1
0.0
0.1
0.2
Temperature (°C)
Heat Flow (W/g)
Sample: Polystyrene; effect anneal @ 95°Size: 11.6600 mg Operator: LabMethod: Anneal Times Run Date: 3-Jun-97 16:41Comment: DSC @ 10°C/min; N2 @ 50cc/min; 12.8mg A1 in ref.; crimped pans
DSC
Anneal Times = 0, 10, 100 & 1000 minutes
DSC: Effect of Annealing Time at 95°Con Shape of Polystyrene Tg
80 90 100 110 120 130- 0. 25
- 0. 20
- 0. 15
- 0. 10
- 0. 05
Temper at ur e ( ° C)
He
at
F
lo
w
(W
/g
)
0. 00Anneal Times = 0, 10, 100 & 1000 minutes
DSC: Effect of Molecular Weighton the Tg (for Styrene Oligomers/Polymers)
Molecular Weight Tg104 -138°C524 - 40°C
2,210 40°C3,100 62°C
15,100 86°C36,000 94°C
170,000 100°C
Turi, pg 249 Kumler, 1977
DSC: Effect of Plasticizer on the Tg
for Polyamides
Water Content (%) Tg (°C)0.35 940.70 841.17 711.99 562.70 454.48 406.61 23
10.33 6
DSC: Effect of Filler and CrystallineContent on the Tg
Decreases magnitude of Cp shift
Broadens temperature range of Glass Transition
Increases the Tg
DSC: Copolymers
0 20 40 60 80 100
370
410
450
490
PPO (wt. %)
Tg
(K)
DSC: Effect of Side Chains on the Tg
for - CH2 - CH(R) -
Side Chain Tg (°C)-H
-CH3
-CH2(CH3)
−C6H5
cyclohexyl
-C6H4 - (4 - C6H5)
-36
-12
64
100
120
161
DSC: Effect of Polymer Backboneon the Tg
N Tg (°C)2 -413 -784 -84
for -O-(CH2)n -
DSC: Effect of Hydrogen Bondingon the Tg
Polyamide Tg (°C) HBondingNylon 12,2 59 LeastNylon 10,2 56Nylon 8,2 93Nylon 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
250.61°C
236.94°C45.30J/g
12.73°C
Peak Temperature
Extrapolated Onset Temperature
Area under the curve (Heat of Fusion)
Width @ half height
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
He
at
Flo
w (
W/g
)
180 200 220 240 260 280 300 320
Temperature (°C)Exo Up
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<500 g/mol)• To is used as the melting temperature (Tm)• Between To and Tp the sample is melting• Between Tp and Te the molten sample is returning to the
DSC temperature
Polymers• Tp is used as the melting temperature (Tm)• Between To and Tp crystal perfection is occurring (both
melting and crystallization occurs simultaneously)• Between Tp and Te the sample is finishing melting and
returning to the DSC temperature
DSC: Polyethylene and Indium Melting
100 110 120 130 140 150 160 170-20
-15
-10
-5
0
5
Temperature (°C)
Hea
t F
low
(m
W)
126.96°C191.7J/g
157.59°C28.46J/g
131.12°C157.85°C
Baseline Types: Linear
12.20°C
22.27(24.02)J/g
16.10°C
1.754J/g
0.0
0.1
0.2
0.3H
eat F
low
(W
/g)
-20 -10 0 10 20 30 40
Temperature (°C)Exo Up Universal V2.5D TA Instruments
Baseline Types: Sigmoidal
12.20°C
23.04J/g
0.0
0.1
0.2
0.3
Hea
t Flo
w (
W/g
)
-20 -10 0 10 20 30 40
Temperature (°C)Exo Up Universal V2.5D TA Instruments
DSC: Observation of Crystallization
100 120 140 160 180 200-1.5
-1.0
-0.5
0.0
0.5
1.0
Temperature (°C)
Hea
t F
low
(m
W)
Tn
Tc152.62°C
163.24°C
139.47°C36.60J/g
Te
DSC: Crystallization Point
Crystallization is a two step process:NucleationGrowth
The onset temperature is the nucleation (T )
The peak maximum is the crystallization temperature (T )
N
C
DSC: PET/ABS Blend "As Received"
50 100 150 200 250-0.8
-0.6
-0.4
-0.2
Temperature (°C)
Hea
t F
low
(W
/g) +
67. 38° C
70. 26° C( H)
120. 92° C
111. 82° C9. 016J/ g
249. 75° C
235. 36° C22. 63J/ g
STANDARD DSCFIRST HEAT ON MOLDED PART
Sample must be pure material, not copolymer or filledMust know enthalpy of melting for 100% crystalline material (∆H )You can use a standard ∆H for relative crystallinity
DSC: Calculation of % Crystallinity
lit
lit
For standard samples:
% crystallinity = 100* ∆Hm / ∆Hlit
For samples with cold crystallization:
% crystallinity = 100* (∆Hm - ∆Hc)/ ∆Hlit
DSC: Polymer Crystallinity - Polyolefin
EN
DO
H
EA
T F
LO
W
E
XO
0TIME (min)
4 8 122 6 10 14
Size: 10.5mg Prog: 5° C/min
190
170
150
130
110
90
TE
MP
ER
AT
UR
E (
°C)H = 141 J/g
% Crystallinity = X 100%141
290= 49%
∆
DSC: Applications
Effect of heating/cooling rate
Crystallization kinetics
Effects of polymer structure/composition
Effects of thermal/mechanical processing
DSC: Effect of Heating Rate onNylon 66 Melting Behavior
1 2 3 4Temperature (°C)
end
o
HE
AT
FL
OW
e
xo
240 260 280 300
0.2 mW
1 mW
5 mW
5 mW
10 mW
50°C/min
20°C/min
10°C/min
2°C/min
0.5°C/min
DSC: Effect of Cooling Rate onCrystallization of HDPE
100 110 120 130-10
10
30
50
70
Temperature (°C)
Hea
t F
low
(m
W)
32°C/min
16 8
4
2
1 0.5
DSC: Crystallization Kinetics
Two step processNucleationCrystal growth
Nucleation may beNaturalInduced (using nucleation agents)
Thermally influenced processNatural nucleationCrystal growthModeled by Isothermal Kinetics using the Autocatalytic Model
DSC: Isothermal CrystallizationProcedure
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
DSC: Isothermal Crystallization ofPolyethylene Terephthalate
0 1 2 3 4 5 6
Time (min)
∆T
T1
T2
T3
T4
T T T1 3 4
< < <T2
Blank run
DSC: Effect of Nucleating Agentson Crystallization
8090100110120130140150T (°C)
Exo
ther
mic
NUCLEATEDPOLYPROPYLENE
NON-NUCLEATEDPOLYPROPYLENE
DSC: Supercooling of Water
-30 -25 -20 -15 -10 -5 0 5 10-50
0
50
100
150
200
250
Temperature (°C)
Hea
t F
low
(m
W)
+-4.36°C
-15.55°C
+
DSC: Purity of PharmaceuticalCompounds
Temperature (°C)
-0.8
-1.0
-1.2
-1.4
-1.6
-1.8
-2.0
-2.2
Hea
t Flo
w (
mW
/mg)
122 126 130124 128 132
Total Area/Partial Area
134 136 138
Purity: 99.55 mole % Melting Pt: 134.9°CDepression: 0.24°CDelta H: 26.4 kJ/moleCorrection: 8.11%Mol. Weight: 179.2 g/moleCell Const: 0.977Onset Slope: 10.14 mW/°C
135.0
134.5
134.0
133.5
133.0
132.5
Tem
pera
ture
(°C
)
108 6420
DSC: Effect of Polymer Typeon Melting
Class Structure Melting RangePolyolefins -CH -CH - 85 - 174°CPolyamides -CH -NH-C(O)-CH - 190 - 265°CPolyesters -CH -O-C(O)-CH - 220 - 270°CPolyphenylene
Sulfides -Ph-S- 300 - 360°C
2 2
2 2
2 2
DSC: Effect of Molecular Weighton Melting
Olefin Formula Mole. Wt. Tm
(g/mol) (°C)C12H26 170 -10C24H50 339 54C30H62 423 66C35H72 493 75
DSC: Effect of Hydrogen Bondingon Melting
Polyamide Tm H BondingNylon 12,2 236 LeastNylon 10,2 242Nylon 8,2 279Nylon 6,2 326 Most
Nylon x,y where:x = carbons in diamine sectiony = carbons in diacid section
DSC: Effect of AnnealingPoly(ethyletherketone) (PEEK) on Melting
Heat F
low
(W/g
)
260 280 300 320 340 360 380-0.3
-0.2
-0.1
0.0
Temperature (°C)
PEEK annealed@ 300°C
PEEK
303.61°C
DSC: Effect of Draw Ratioon Melting Temperature
1.0 3.0 5.0 7.0129
133
137
λ
Tm
(°C
)
DSC: Effect of Aromaticity on Melting
Polymer % Aromatic Melting Range
-CH2 - CH2 - 0 105 - 135°CPET 39 250 - 275°C-(Ph)-O- 62 300 - 315°C-(Ph)-S- 70 300 - 360°C
DSC: Effect of Branching on Melting
Polyolefin Branching Tm
LDPE irregular ~ 105°Crandom lengths
LLDPE irregular ~ 127°Cfixed lengths
HDPE none ~ 135°C
PP regular ~ 150°Cfixed 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.
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: Specific Heat Capacity
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 andSpecific 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 ShiftsHeat Flow
40 60 80 100 120 140 160 180 200-10
-8
-6
-4
-2
0
Temperature (°C)
Hea
t F
low
(m
W)
5°C/min
10°C/min
20°C/min
106. 85° C- 2. 137mW
106. 85° C- 40175mW
106. 85° C- 8. 104mW
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)
DSC: Specific Heat Capacity Equation
Cp = E x H x 60
Hr x M
DSC: Specific Heat CapacityStep 1. Run Empty Pans
Create Thermal Method, e.g.,
1) Equilibrate @ 50°C2) Isothermal for 10 min.3) Ramp 20°C/min to 300°C4) Isothermal for 10 min.
Run Empty Pans to determine background heat flow
Subtract background heat flow from subsequent measurements
DSC: Specific Heat CapacityStep 2. Determine Value of E
E is temperature-dependant
Heat sapphire disc (Cp standard) through thermal profile
At temperature of interest, calculate E
DSC: Specific Heat CapacityStep 2. Determine Value of E (cont.)
For example, at 380 K (106.85°C), sapphireCp = 0.9161 J/g/°CM = 25.20mgHr = 20°C/minMeasured Heat Flow = 7.25 mW
E = (0.9161 mJ/mg/°C) x (20°C/min) x (25.20 mg)
(7.25 mW (mJ/sec)) x (60 sec/min)
Cp Hr M
H
at 380K, E = 1.06
DSC: Specific Heat CapacityStep 3. Measure Unknown Sample
Use exact same thermal profile as empty pans and sapphire
Measure sample mass, e.g., 14.20 mgMeasure Heat Flow at 380K, e.g., 4.60 mWSubstitute E into equation on page 103.
Cp = (1.06) x (4.60 mW (mJ/sec)) x (60 sec/min)
(20°C/min) x (14.20 mg)Hr M
HE
Cp = 1.030 mJ/mg/°C (J/g/°C)
DSC: What Affects the Specific HeatCapacity?
Amorphous Content
Aging
Side Chains
Polymer Backbone
Copolymer Composition
DSC: Effect of Amorphous Contenton 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 heatcapacity.
DSC: Effect of Annealing(Crystallization) on Cp of PEEK
100 110 120 130 140 150 1601.2
1.4
1.6
1.8
2.0
2.2
Temperature (°C)
Co
mp
lex
Cp
(J/
g/°
C)
Amorphous PEEKPEEK annealed at 300°CPEEK annealed at 330°C
DSC: Effect of Aging on the SpecificHeat Capacity of Polystyrene
360 380 400 420Temperature (K)
End
oth
erm
406
272
240120
66
24
3
0
tg (h)
DSC: Effect of Side Chains on SpecificHeat Capacity
Polymer Side Chain Cp (J/g/°C)PE -H 2.763PP -CH 2.752PS -Ph 2.139
As the steric bulk of the side chain increases, molecular mobility decreases resulting in lower specific heat.
B. Wunderlich, ATHAS Cp Data Bank, 1985.
DSC: Effect of Polymer Backbone on Specific Heat Capacity of Polyoxyalkenes @ -153°C
# of Methylenes Cp (J/g/°C)
1 0.62262 0.69183 0.70884 0.75978 0.7736
OCH2n)
O([ ]
As the number of methylenes increase, mobility isincreased 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 15.127.5 random 16.39
15.5 random 18.54
As PP concentration is increase, the number of methylenesincreases, resulting in a rise in specific heat capacity. Also, with randomness comes entropy, increase in mobility, and increasein specific heat capacity.
B. Wunderlich, ATHAS Cp Data Bank, 1985.
Theory
Signals
Applications
Experimental Conditions
Calibration
DSC: Modulated DSCTM
MDSC Theory
Heat Flow Equation
),( tTfdt
dTCp
dt
dH+=
dHdt
= Total Heat Flow measured by the calorimeter
Cp = Specific Heat Capacity
dTdt
= Underlying Heating Rate
f(T,t) = kinetic response of sample
Heat Flow Due to Heat Capacity
4060
80100
120140
160180
200
Temperature (°C)
(10)
(8)
(6)
(4)
(2)
0
Hea
t F
low
(m
W)
5°C/min
10°C/min
20°C/min
106.85°C-2.137mW
106.85°C-4.018mW
106.85°C-8.104mW
Kinetic Heat Flow
time0 t t1 2
Hea
t Flo
w
The magnitude of measured kineticheat flow is a function of time at aconstant temperature.
Isothermal Temperature
Standard DSC Measures the Sum of Heat Flow
Temperature
Hea
t Flo
w
Heat Flow due toHeat Capacity
Heat Flow due toKinetic Events
Heat Flow Can Be Separated
Heat Flow due toHeat Capacity
Heat Flow due toKinetic Events
f(T,t)
CpdT
dt
Temperature
Hea
t Flo
w
General Theory of MDSC
Heat flow from DSC experiments is composed of two partsbut DSC can only measure the sum of the two.
dH/dt = Cp (dT/dt) + f (T,t)
Total = Heat Capacity + KineticHeat Flow Component Component(DSC) = Heating Rate + Time Dependent Dependent
= MDSC Reversing + MDSC Nonreversing
Distribution of Transitions in MDSC Experiments
Total = Heat Capacity + KineticComponent Component
= Reversing Heat Flow + Nonreversing Heat Flow
glass transition melting (some)
enthalpic relaxationevaporationcrystallizationdecompositioncuremelting (some)
Physical Measurement Technique
Apply Stimulus Measure ResponseStimulus Response
FTIR IR Radiation AbsorbanceWavelength
NMR Magnetic Field ResonanceFrequency
X-Ray Diffraction X-Ray Radiation Angle ofDiffraction
MDSC SinusoidalHeating Rate
Amplitude ofHeat Flow
Raw Signals in MDSC
TimeModulated Temperature (Stimulus)Modulated Heat Flow (Response)
All Modulated DSC Signals are derived fromthree measured parameters.
MDSC Raw Signal
MODULATED HEAT FLOW(Response) CRYSTALLIZATION DURING MELTING
MELTING
GLASS TRANSITION
COLD CRYSTALLIZATION
NOTE: ALL TRANSITIONS OFINTEREST ARE CONTAINED INMDSC RAW DATA SIGNALS
MODULATED HEATING RATE(Stimulus)
50 100 150 200 250 300
0
2
4
6
8
-0.6
-0.4
-0.2
0.0
0.2
Temperature (°C)
Deriv. Modulated Temp (°C/min)
Modulated Heat Flow (W/g)
Temperature Change (MDSC)
200
210
220
230
240
Mo
dul
ate
d T
em
p (
°C)
200
210
220
230
240
Te
mp
era
ture
(°C
)
38 39 40 41 42 43 44 45
Time (min)
Exo Up Universal V2.5D TA Instruments
ACTUAL MEASURED TEMPERATURE
CALCULATED AVERAGE
TEMPERATURE
PA
MDSC Signals: Total Heat Flow
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
Total Heat Flow: Average of Modulated Heat Flow Signal
50 100 150 200 250 300-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
-0.4
-0.2
0.0
0.2
Temperature (°C)
Modulated Heat Flow (W/g)
Heat Flow (W/g)
MDSC Signals: Heat Capacity
Where:AMHF = Amplitude of Modulated Heat FlowAMHR = 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 conventional DSC experiments at different heating rates.
K x A
A Cp
MHR
MHF=
Conventional DSC Cp Measurement
x wtRateHeat
HF– HFK x Cp
MTS=
HF
endo
0HFMT
HFS
Temp.
Where:
K = Calibration constant
HFS = Differential heat flow with sample
HFMT = Differential heat flow with empty pans
wt = weight of sample
Alternative DSC Cp Measurement
HF
endo
0HFHR1
HFHR2
Temp.
wt)HR– (HR
HF– HFK x Cp
12
HR1HR2=
Where:
K = Calibration constant
HFHR1 = Differential heat flow of sample at HR1
HFHR2 = Differential heat flow of sample at HR2
HR2 = Heating rate 2
HR1 = Heating rate 1
wt = weight of sample
Heat Capacity from MDSC Raw Signals
50 100 150 200 250 300
0
5
10
-0.6
-0.2
0.2
0.6
Temperature (°C)
Deriv. Modulated Temp (°C/min)
Modulated Heat Flow (W/g)
4
2
0
2
4
6
Complex Cp (J/g/°C)HEAT CAPACITY
MODULATED HEAT FLOW
MODULATED HEATING RATE
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
t)(T, dt
dT Cp
dt
dHf+=
Basis for Calculation
ing)(Nonrevers process kinetic from flowheat t)(T,
)(Reversingcomponent capacity heat dt
dT Cp
rate heating average dt
dT
capacityheat measured Cp
flowheat total dt
dH
:Where
=
=
=
=
=
f
Reversing Heat Flow from MDSC Raw Signals
50 100 150 200 250 300
-8
-4
0
4
8
-0.25
-0.15
-0.05
0.05
0.15
Temperature (°C)
Co
mp
lex
Cp
(J/
g/°
C)
Rev
Hea
t F
low
(W
/g)
HEAT CAPACITY
REVERSING HEAT FLOW
Quench Cooled PET: Total vs. Reversing Heat Flow
50 100 150 200 250 300-0.3
-0.2
-0.1
0.0
0.1
-0.25
-0.15
-0.05
0.05
0.15
Temperature (°C)
Hea
t F
low
(W
/g)
[
]R
ev H
eat
Flo
w (
W/g
)
TOTAL
REVERSING
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
ing)(nonreverscomponent kinetic t)(T,
)(reversingcomponent capacity heat dt
dT Cp
flowheat total dt
dH
t)(T, dt
dT Cp
dt
dH
=
=
=
+=
f
f
Quench-Cooled PET: Deconvoluted Signals
50 100 150 200 250 300-0.25
-0.15
-0.05
0.05
0.15
0.25
-0.25
-0.15
-0.05
0.05
0.15
0.25
Temperature (°C)
Hea
t F
low
(W
/g)
Rev
Hea
t F
low
(W
/g)
-0.2
-0.1
0.0
0.1
No
nre
v H
ea
t F
low
(W
/g)
NONREVERSING
TOTAL
REVERSING
Glass Transition of Polymer Resin
MDSC: Glass Transition of Epoxy Coating
0 20 40 60 80 100 120 140-0.30
-0.28
-0.26
-0.24
-0.22
-0.20
-0.10
-0.08
-0.06
-0.04
-0.02
0.00
Temperature (°C)
Hea
t F
low
(m
W)
Rev
Hea
t F
low
(m
W)
TOTAL
REVERSING
NOTE: Sensitivity is 100µW Full Scale
PET/ABS Blend - Conventional DSC
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-0.8
Temperature (°C)50 100 150 200 250
Hea
t Flo
w (
W/g
)
first heat on molded part
(Curve shifted on Y axis to avoid overlap)
second heat after 10°C/min cooling
120.92°C67.38°C
70.262°C (H)235.36°C
111.82°C9.016J/g
22.63J/g
249.75°C
9.22 mg sample, nitrogen purge 10°C/minute heating rate
PET/ABS - MDSC
8.46mg sample
nitrogen purge
2°C/minute heating rate, ±1°C amplitude, 60 second period
first heat on molded part
PET Tg
ABS Tg
-0.10
-0.11
-0.12
-0.13
-0.14
-0.15
Temperature (°C)
40 60 100 120 140
Hea
t Flo
w (
mW
)
20 80 160
-0.02
-0.03
-0.04
-0.05
-0.06
-0.04
-0.05
-0.06
-0.07
-0.08
-0.09
(
)
Non
rev.
Hea
t Flo
w (
W/g
)
(
)
Rev
. Hea
t Flo
w (
W/g
)
67.00°C+72.89°C (H)
104.45°C
107.25°C (H)
180 200
MDSC: Detection of Two GlassTransitions in PC/PEE Blend
40 60 80 100 120 140 160
-0.12
-0.10
-0.08
-0.06
-0.04
-0.02
-0.005
-0.004
-0.003
-0.002
-0.001
Temperature (°C)
Re
v H
eat
Flo
w (
W/g
)
De
riv.
Re
v H
ea
t F
low
(W
/g/m
in)
3 CONSECUTIVE HEATING RUNS AFTER 2deg/min COOLING
DERIVATIVE
NOTE 81°C WIDTH OF GLASS TRANSITION
3
2
1
62. 58° C
141. 45° C
MDSC ±0.424°C, 40 sec. period4°C/min underlying ramp rate
+
+
MDSC: Heat Capacity for PET DuringIsothermal Steps
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
1.0
1.2
1.4
1.6
60
80
100
120
140
Time (day)
Hea
t C
apac
ity
(J/g
/°C
)
Tem
per
atu
re (
°C)
PLOT vs TIME
Heat Capacity
Temperature
MDSC ±0.30°C, 40 sec. period1°C isothermal steps
MDSC: PET Heat Capacity During GlassTransition & Cold Crystallization
60 70 80 90 100 110 120 130
1.1
1.2
1.3
1.4
1.5
1.6
Temperature (°C)
Hea
t C
apac
ity
(J/g
/°C
)
COLD CRYSTALLIZATION(First-Order Transition)
GLASS TRANSITION(Second-Order Transition)
MDSC ±0.30°C, 40 sec. period1°C isothermal steps
Isothermal Epoxy Cure
∆H of Cure6
4
2
0
Time (min)5 10 20 25 30
Non
rev.
Hea
t Flo
w (
mW
)
Heat Capacity
Isothermal 80°C helium purge ±0.5°C amplltude 60 second period
DMA 1Hz
0 15 35 40
30
20
10
0
(
)
Hea
t Cap
acity
(m
J/°C
)14.5
14.0
13.5
13.0
12.5
12.0
11.5
(
)
E' (
GP
a)
MDSC: Heat Capacity vs. Cure TimeTM =Epoxy-Amine System MDSC Result at 70°C Cure
Thermochimica Acta, 268, 121-142 (1995), Dr. B. Van Mele, et alat Vrije Universiteit Brussels (Belgium)
=
0 100 200 3000
30
60
90
120
1.0
1.5
2.0
2.5
Time (min)
(
)
No
nre
vers
ing
Hea
t F
low
(m
W/g
)
(
) H
eat
Cap
acit
y (J
/g/K
)
exo
t1/2 Cp∆
t1/2 Cp
vit
= 97 mi
X = 0.53∆
Nonreversing Heat Flow
Heat Capacity
MDSC: Experimental Considerations
Modulation Period?
Modulation Amplitude?
Sample Dimensions?
Purge Gas?
Sample Preparation?
Phase Correction?
Calibration?
MDSC: Sample Preparation
Thin, Low Mass SamplesMinimize Thermal GradientsAllow for Faster Periods, Larger
Modulation Amplitudes
Thicker, Heavier SamplesMinimize Baseline CurvatureImprove Sensitivity
Low, Consistent MassBest Choice for MDSC MeasurementsSolids, Powders, FilmsVolatility may be an issue
MDSC: Sample PansStandard Crimped
MDSC: Sample PansStandard Hermetic
Use for liquid/volatile samplesHigher Mass, Less SensitivityUse Heat Sink Compound
NitrogenEconomicalWide Operating RangeProvides Good Sensitivity
HeliumHigher Thermal ConductivityFacilitates Wider Range of Modulation ConditionsReduces Baseline Curvature
MDSC: Purge Gas
MDSC: Purge Gas Flow Rates
Use Purge Gas Flow Rate of 50 mL/min. (N2) & 25 ml/min (He)
Faster rates increase noiseSlower rates decrease sensitivity, increase baseline curvature
Flow Purge Gas through Vacuum Portat 50 mL/min.Improves response of furnaceFacilitates wider range of modulationparameters
MDSC: Baseline Calibration
Identical to Standard DSC experimentEliminates Baseline DriftDoes not affect curvature -Slower heating rates contribute tocurvature-Heavier sample masses minimize curvature
-200 -100 0 100 200 300 400-10
-8
-6
-4
Temperature (°C)
Del
ta (
V
)µ
Baseline Calibration - 2920 MDSC (4)<
Sample: Empty Pans DSC File: D:\TA\DSC\...BASE1102.001
Baseline CalibrationSlope: -0.0005Offset: -8.564Cell Number: 319
-90.29°C287.04°C
MDSC: Heat Flow (Cell Constant)Calibration
Identical to Standard DSC CalibrationBaseline Calibration - 2920 MDSC (4)v
Sample: Indium Metal DSC File: D:\TA\DSC\DATA\CAL0512.001
150 152 154 156 158 160 162 164-25
-20
-15
-10
-5
0
Temperature (°C)
Hea
t F
low
(m
W)
Cell Constant CalibrationIndium Standard Heat: 28.71 J/gCell Constant: 1.5555Onset Slope: -40.63 mW/°CCell Number: 319
157.74°C
MDSC: Cell Constant Effect onModulated Heat Flow
25 75 125 175 225 275-4
-2
0
2
4
Temperature (°C)
Mo
du
late
d H
eat
Flo
w (
mW
)
E = 0.5E = 1.0E = 1.6
MDSC: Heat Capacity Calibration
Provides for Accurate Heat Capacity MeasurementsUse Either Sapphire Disc (wide temperature range) or HDPE (polymer melt)Choose one-point or average valuesEffects of Experimental Conditions
MDSC: Heat Capacity Calibration-Frequency Dependence
0.8
0.9
1
1.1
1.2
1.3
0 10 20 30 40 50 60 70 80 90 100
Temperature (°C)
K(C
p)
10 Sec20 Sec30 Sec40 Sec50 Sec60 Sec70 Sec80 Sec90 Sec100 Sec
MDSC: Heat Capacity CalibrationFrequency Dependence (cont.)
0.85
0.87
0.89
0.91
0.93
0.95
0 10 20 30 40 50 60 70 80 90 100
Temperature (°C)
K(C
p)
40 Sec50 Sec60 Sec70 Sec80 Sec90 Sec100 Sec
MDSC: Heat Capacity CalibrationAmplitude Dependence
0.84
0.85
0.86
0.87
0.88
0.89
0.9
0.91
0.92
0.93
0.94
0 10 20 30 40 50 60 70 80 90 100Temperature (°C)
K(C
p)
0.10°C0.25°C0.50°C0.75°C1.00°C1.25°C1.50°C1.75°C2.00°C
MDSC: Heat Capacity Calibration -Heating Rate Dependence
0.84
0.86
0.88
0.9
0.92
0.94
0 10 20 30 40 50 60 70 80 90 100
Temperature (°C)
K(C
p)
1°C/min
3°C/min
5°C/min
Isothermal
Effect of Modulation Conditions on K
Period (sec)
Each color gradient represents a 5% change in K.
10 20 30 40 50 60 70 80 90 1000.1
0.2
0.4
0.81
1.21.4
1.61.8
2
1.00
1.10
1.20
1.30
1.40
1.50
1.60
K
Amplit
ude (±°C
)
He purge @ 25 ml/min.