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DSC原理與應用
TA Instruments User Training
許炎山
TA Instruments, Waters LLC
美商沃特斯國際股份有限公司台灣分公司
TA Taipei office: 104臺北市長安東路1段23號4F之5
Tel: 02-25638880 Fax: 02-25638870
C/P: 0928-168676 E/M : [email protected]
2012年9月7日國立台灣大學化學系 潘貫講堂 (B棟積學館2樓演講廳)
基礎原理
何謂熱分析 (Thermal Analysis)?
搜集物質的物理特性隨著控制溫度(環境)或時間變化下所相應的函數關係之技術稱為“熱分析”.
溫度
性質
Melting
melting point crystallinitysoftening
purity
Oxidation
OITstabilizersburning profile
Decom-position
temperaturecontentkinetics
Temperature highlow
Heating
heat capacityexpansivity
modulus
O2
何謂熱分析 (Thermal Analysis)?
Melting point / melting rangeCrystallization behavior Glass transition temperatureCoefficient of thermal expansionThermal stabilityDecomposition temperatures and kineticsOxidation induction time / temperature , OITCrosslinking behaviorPurityVisco-elastic properties: modulus, damping and creep Swelling behaviorThermal Conductivity Thermal Diffusivity
Material Properties
何謂熱分析 (Thermal Analysis)?
Chemical Reactions and Properties
Reactions between components in the formulation or the atmosphereEffect of catalystsChemical bonding of plasticizersCrosslinking reactionsChain scissionOxidative reactionsDegradation breakdownMolecular structure and bond strengthsChemical weather and ageing effectsEffect of additivesPolymerizations
何謂熱分析 (Thermal Analysis)?
Specific heat capacityPhysical transitionsMass or weight changesMechanical properties such as dimension, deformation, storage and loss modulusThermal Conductivity / Thermal DiffusivityNature of evolved gas
Physical Properties
何謂熱分析 (Thermal Analysis)?
ApplicationIndustryPolymersFoodCosmeticsForensicsTextilesElectronicsAutomotiveAerospacePackagingBiochemistry
BiopolymersCeramics MetalCompositesAdhesivesPaintsLacquersResinsPharmaceutical…
Research & DevelopmentQuality ControlService LabsAcademia
何謂熱分析 (Thermal Analysis)?
Glass transitionCrystallizationMeltingDegradationOxidationPhase transitionsCompatibilityIdentificationPolymers
Polymers
何謂熱分析 (Thermal Analysis)?
PolyolefinsResinsAdhesivesBlendsCompositesPaints
Polymorphism
Crystallization
Phase transitions
Identification of components
Compatibility
Stability
Purity
Binary phase diagrams
Moisture
Pharmaceuticals
何謂熱分析 (Thermal Analysis)?
Drugs Drug delivery systemsExcipients Manufacturing additivesPackaging materials
FormulationCompatibility StabilityPolymorphismGlass transitionCrystallizationRaw material identificationOrganic contentPigment color analysisWater content
Cosmetics
何謂熱分析 (Thermal Analysis)?
LipsticksFatsWaxesCreamsNail varnish Polymer packaging
PolymorphismIdentification of componentsCrystallizationThermal historyStabilityGlass transitionVaporizationDenaturizingVisco-elastic behaviorSwelling
Food
何謂熱分析 (Thermal Analysis)?
Edible fats and oilsFatty acidsCocoa butterStarchSugarProteins
Identification of components
Crystallization
Phase transitions
Binary phase diagrams
Polymorphism
Hazard analysis
Oxidation stability
Petrochemicals and Organic Chemicals
何謂熱分析 (Thermal Analysis)?
ExplosivesLubricantsParaffinWaxesPitches Liquid CrystalsOils
Glass transitionCrystallizationMeltingDegradationOxidationReactionPhase transitionsCompatibilityWater determinations
Inorganics
何謂熱分析 (Thermal Analysis)?
Calibration standardsCarbonatesCementCoalFillersHydratesGypsumMetals and alloysGlassCeramicsMinerals
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
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: DefinitionsA 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
ΔH = Cp ΔTor in differential form
dH/dt = Cp dT/dt + thermal events
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 是熱分析家族的入門基礎
Perkin Elmer introduced the Power Compensation DSC 1 in 1966Dupont introduced the Heat Flux DSC 10 in 1968
兩大主流:熱流式 Heat Flux DSC補償式 Power Compensated DSC
When an exothermic or endothermic change occurs inthe sample, power(energy) is applied or removed from the furnace to compensate for the energy changeoccurring in the sample. The system is maintained in“Thermal Null” state all the time. The amount of powerrequired to maintain the system in equilibrium is directlyproportional to the energy changes.
電能補償式 Power-Compensation Principle
Sample ReferencePlatinum Alloy
PRT Sensor
Platinum
Resistance Heater
Heat Sink
PE
Produced Inform
ation
Typical Power Compensation DSC Cell
ΔT (ΔP)
Insulating Heat Sink
Sample Furnace Reference FurnaceSample Reference
Platinum Resistance Thermometers (PRT)
Platinum Resistance Thermometers(PRT)=Sample Temperature
Power Compensation Baseline Curvature(Best case scenario)
100 150 200 250 300 350 400
0
1
2
3
4
5
6
7
Sample Temperature in 蚓
Hea
t Flo
w in
mW
50 450
Baseline run to run (SB1)Y value @ 140蚓
first heat = 5.750 mWsecond heat = 5.730 mWthird heat = 5.730 mWfourth heat = 5717 mWfifth heat = 5.732 mWsixth heat = 5.789 mW
baseline, run to run: SB1A2.DCDHeat Flow in mW: Step: 2baseline, run to run: SB1A2.DCDHeat Flow in mW: Step: 8baseline, run to run: SB1A2.DCDHeat Flow in mW: Step: 10baseline, run to run: SB1A2.DCDHeat Flow in mW: Step 14baseline, run to run: SB1A2.DCDHeat Flow in mW: Step 18baseline, run to run: SB1A2.DCDHeat Flow in mW: Step 22
熱流式 Classical DSC: Measurement of HF and
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 ΔUTemperature Difference ΔT
Heat Flow dQ/dt
DSC: How Heat Flux is Measured
• Heat flow through the chromel wafer causes a temperature difference ΔT. The temperature difference is measured as the voltage difference ΔUbetween the sample and reference constantan/chromel junctions. The voltage is adjusted for thermocouple response S and is proportional to heat flow.
ΔT = ΔU / S ΔT in °CΔU in µVS in µV/°C
Triac Board
Main CPU Board
Controller
ΔH = Cp ΔT or in differential formdH/dt = Cp dT/dt + thermal events
where: Cp = specific heat (J/gOC)T = temperature (OC)
H = heat (J)dH/dt = heat flow (J/min)
mW = mJ/secdT/dt = heating rate (OC/min)
assuming work & mass loss are zero
Metal 1 Metal 2 Metal 1 Metal 2
Sample Temperature
Referance Temperature
TemperatureDifference = Heat Flow
傳統熱流式 DSC 運作邏輯示意圖
Classical Heat Flux DSC, TA Instruments
Constantan Disc
Silver Furnace
Sample Thermocouple
Chromel DiscChromel Disc
Sample PanReference Pan
Reference Thermocouple
DSC 10DSC 910DSC 920DSC 2010DSC 2910DSC 2920
Gas Purge Inlet
Gas Purge Outlet
TA Instruments DSC 2XXX
DSC 2010 DSC 2910 DSC 2920
Q1000/Q2000
Q100/Q200Q10/Q20
TA Instruments DSC Q Series
TA Instruments DSC 電腦控制技術的進展
Dupont Controller 9900 + 獨立interface + X-Y Plotter IBM TA2000/RMX + 獨立interface + X-Y Plotter/IBM PrinterIBM TA4000/OS2 + 內建interface + PrinterPC TA5000/Windows +內建interface + 各種圖譜輸出功能
PC TA Advantage/Windows +內建interface + 全方位輸出功能
獨立 interface : DSC 10/910/920內建 interface : DSC 2010/2910/2920/Q Series 內建工作站 : Discovery DSC
Heat Flux DSC: Theoretical ΔT Measurement
ΔT
To Tp
Tr = Reference TemperatTs = Sample TemperatureTo = Onset of MeltTp = Peak of Melt
Theoretically: To = TpTime
Tem
pera
ture
Actual Heat Flux Data
156.0
156.5
157.0
157.5
Ref
eren
ce T
empe
ratu
re ( 蚓
)
156.0
156.5
157.0
157.5Sa
mpl
e Te
mpe
ratu
re ( 蚓
)
5.2 5.3 5.4 5.5 5.6 5.7 5.8
Time (min)
Slope due to thermal lag
ΔT
Actual Heat Flux Data
-4
-2
0
Del
ta T
/Hea
t Flo
w
156.0
156.5
157.0
157.5
Ref
eren
ce T
empe
ratu
re (蚓
)
156.0
156.5
157.0
157.5Sa
mpl
eTem
pera
ture
(蚓)
5.2 5.3 5.4 5.5 5.6 5.7 5.8
Time (min)Exo Up
Conventional DSC Measurements
Heat FlowMeasurement Model
This model assumes that the sample and reference calorimeter thermal resistances are identical, the temperature of the furnace at the sample and reference calorimeters are equal and does not include other known heat flows.
s
sfss R
TTq
−=
r
rfrr R
TTq
−=
Heat Balance Equations
rs qqq −=
RT
RTTq sr Δ−
=−
=
Conventional DSC HeatFlow Rate Measurement
Assumptions Achieved Through Mechanical Means
Uniform Furnace TemperatureHigh Conductivity Silver Furnace
Uniform Thermal ResistanceMechanical Symmetry
Differential TemperatureSeries Opposed Thermocouple System
Other Assumptions
Cs = CrMs = MrCps = CprMps = MprRd is very largeRps = Rpr and is very small
• The heat flow rate of an empty perfectly symmetrical twin calorimeter should be zero.
• However it almost never is because the DSC is rarely symmetrical as assumed.
• The asymmetry is the inevitable result of manufacturing tolerances and is practically unavoidable.
For example, thermal resistance of the Tzero ® DSC cell is determined by the wall thickness of the “top hat” which is 0.127 mm. To achieve 1% thermal resistance imbalance would require a manufacturing tolerance of 0.00127 mm.
Symmetry is Assumed, Rarely Achieved
Why Tzero® ?• To remove the erroneous contribution to the
thermogram from the calorimeter itself.
Q Series Tzero® Transducer (2001)
Sample PlatformReference Platform
Constantan Body
Constantan Wire
Chromel Wire
Chromel Wire
Thin Wall Tube
Chromel Area Detector
Q-Sries New Tzero™ DSC CELL SCHEMATIC
Constantan Body
Chromel Wire
Chromel Area Detector
Constantan Wire
Chromel Wire
Base Surface
Thin Wall Tube
Sample Platform
Reference Platform
Tzero™ SENSOR
New Chromel/Constantan Tzero™ sensor located midway between the sample and reference platforms.
Tzero™ sensor acts as control sensor to assure precise isothermal furnace operation. The Tzero™ sensor is also used to calculate the four term heat flow.
Tzero Thermosensitive Area
In the TA Instruments design, the entire surface of the sample and reference platform represents thermosensitive area.This area is roughly 17.8 mm2
The chromel-constantan thermocouple is a high-ouput device
Thermosensitivearea detector
Tzero Principle of Operation
TrTs
Rs
Cs Cr
RrTo
Tf
The Tzero™ thermocouple provides anobjective reference point so that those
factors previously assumed can be directlymeasured.
Tzero™ DSC Measurement Model
Rs Rr
qs qr
Cs Cr
Tr
T0
Ts
τddTC
RTTq s
ss
ss −
−= 0
Heat Balance Equations
τddTC
RTTq r
rr
rr −
−= 0
Heat FlowSensor Model
Tzero® Heat Flow Equation
Tzero Heat Flow Equation
ΔT = Ts – Tr & ΔT0 = T0 - Ts
( )01 1 s
r sr s r
T dT d Tq T C C CrR R R d dτ τΔ Δ⎛ ⎞= − + Δ − + − −⎜ ⎟
⎝ ⎠
• Principal DSC Heat Flow• Thermal Resistance Imbalance• Heat Capacity Imbalance• Heating Rate Difference
Tzero™ Heat Flow Term Contributions
Principal heat flow provides main heat flow signalThermal resistance and heat capacity imbalance terms improve baselineHeating rate difference term improves resolution and MDSC performance
( )ττ dTdC
ddTCC
RRT
RTq r
ssr
rsr
Δ−−+⎟⎟
⎠
⎞⎜⎜⎝
⎛−Δ+
Δ−=
110
What is Pan Contact Resistance?
DSC Pan
Heat Flow Sensor
Heat Flow
Imperfect (non-intimate) contactbetween pan and sensor causes lagin heat flow which decreases resolution
Incorporating Pan Contact Resistance
Rs Rr
qs qr
Cs CrTr
T0
Ts
Rp Rp
mpscpan mprcpan
Tps Tpr
qsam
Sensor
Pan
A model was derived which incorporates pan contact resistance into the heat flow equation
Tzero® Benefit: Improved Baseline Shape
-150
-100
-50
0
50
100
150
-100 0 100 200 300 400
Hea
t Flo
w (μ
W)
Temperature (°C)
Heat Flow T1 µWHeat Flow T4 µW
( )01 1 s
r ss rr
d TC
dTT C C
R R drq
TdR τ τ
⎛ ⎞+ Δ − + −⎜ ⎟ −⎝ ⎠
ΔΔ−=
rq T
R=
Δ−
Tzero® Benefit: Improved Peak Resolution
( )01 1 s
r ss rr
d TC
dTT C C
R R drq
TdR τ τ
⎛ ⎞Δ − + −⎜ ⎟ −⎝ ⎠
+ΔΔ
−=
-8
-7
-6
-5
-4
-3
-2
-1
0
1
150 152 154 156 158 160 162 164
Hea
t Flo
w (W
/g)
Temperature (°C)
Heat FlowT1
rq T
R=
Δ−
Advanced Tzero™ Results
61 65 69 73 77Temperature (蚓 )
-25
-20
-15
-10
-5
0H
eat F
low
(mW
)
Advanced TzeroTzero DSCConventional DSC
Advanced Tzero DSC 1.13 mg Dotriacontane 10蚓 /min
But, Tzero is only as good as the measured signals: ΔT, ΔT0 & Ts
The objective of the Discovery DSC Technology is to realize the full potential of the Tzero® method by
dramatically improving the measured signals
Discovery DSC Objective
New Sensor - Objectives
Improve sensor flatness to reduce pan/sensor contact resistance variations
Reduce distortion due to thermal expansion difference between chromel area thermocouples and constantan platformsRealize full benefit of Tzero sample pans – reduce pan contact resistance and variation
Pan Contact Resistance
New Sensor - Objectives
Optimize thermocouple locationThermocouple should not be in pan/sensor contact zone because inevitable variations in the magnitude and distribution of contact resistance reduces the repeatability of the differential temperature measurementsLocate thermocouple so that ΔT and ΔT0 measurements are unaffected by pan contact resistance variations
Discovery DSC Transducer
High strength bondImproved flatness of pan/sensor contact region by 6xNo alloying of thermocouple by welding
• Optimum thermocouple placement: junction at circumference
0.37
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3 4 5 6 7 8 9 10
Nor
mal
ized
Hea
t Flo
w
Time (sec)
T1 Normalized Heat Flow
Q2000 T4P Normalized Heat Flow
Discovery DSC Normalized Heat Flow T4P
Time Constant Comparison
Discovery DSC Time Constant: ~0.8 s
-12
-10
-8
-6
-4
-2
0
2
152 153 154 155 156 157 158 159 160 161 162 163
Hea
t Flo
w (m
W)
Temperature (°C)
Indium Response Ratio
Q20: 8Q2000: 60
Discovery DSC: >90
Q SERIES AUTOLID AND TOUCH SCREEN
Autolid – automates placement and removal of DSC lids and thermal shields providing repeatable thermal isolation of the cell.
Integrated Touch Screen – for local control and monitoring of experiment, real time signals, and time remaining. Automatic autosampler calibration is initiated from this screen.
MASS FLOW CONTROLLER
Accurate, settable purge gas flow that eliminates flow meters
Settable in method
Includes gas switching
Easy to use Legris fittings
Autolid IIDesign Improvements
Redesigned Autolid IIEasier adjustmentBetter lid placement precisionMore efficient purge gas exhaustBetter Temperature/Tzero Stability
Tzero™ DSC CELL SCHEMATIC
Silver Base for Cell Lid #1
Measuring Chamber
Silver Base for Cell Lid #2
Furnace
Tzero™ Sensor
54 Nickel Cooling Rods
Cooling Flange
Chambers for Temperature Conditioning
of Purge Gas
COOLING OPTIONS : FACS
Finned Air Cooling System (FACS) – Innovative (silent!) system that uses house air to cool the DSC to ambient temperatures. Can be used for cooling experiments, and thermal cycling. Cost effective alternative to Refrigerated and Liquid Nitrogen systems for work at ambient temperatures and above.
LIQUID NITROGEN COOLING SYSTEM
Temperature range= -180 to 550 °C
Cooling Rates= 85 °C/ min to 100 °C= 50 °C/min to 0 °C= 25 °C/min to – 100 °C
Baseline Bow= <30 μW (-100 to 300 °C)
Baseline Repeatability= < 40 μW
Baseline Noise= < 1.5 μW p-t-p
COOLING OPTIONS : RCS
Refrigerated Cooling System (RCS)
RCS90 can achieve lower temperatures (-90C).
RCS40 can achieve lower temperatures (-40C).
Q SERIES AUTOSAMPLER
Ultra-reliable autosampler with patented new optical sensor. Compatible with multiple pan types. Works perfectly with all automated cooling systems. Self calibrating.
Q SERIES Pressure DSC
Pressure Cell
1. Q20 PDSC2. Q1000/Q2000 PDSC
Q SERIES Photo-DSC
Q SERIES Optical-DSC
This hole is sized to the probe diameter.
Universal Optical Accessory Kit
NIR, RAMAN
