DSC專業(yè)知識講座

DifferentialScanningCalorimetry(DSC)Theory&Applications第1頁差示掃描量熱儀(DSC)DSC測量樣品吸熱和放熱與溫度或時間關(guān)系吸熱熱流入樣品，即樣品吸取外界熱量，為負值。放熱熱流出樣品，即樣品對外界放出熱量，為正值。國際標準ISO11357-1:：

DSC就是測量在程序控制溫度下，輸入到試樣和參比物之間功率差（dH/dt）與溫度(T)關(guān)系一種技術(shù)。該熱流差能反應樣品隨溫度或時間變化所發(fā)生焓變：樣品吸取能量時，焓變?yōu)槲鼰?；當樣品釋放能量時，焓變?yōu)榉艧帷５?頁EndothermicHeatFlowHeatflowsintothesampleasaresultofeitherHeatcapacity(heating)GlassTransition(Tg)MeltingEvaporationOtherendothermicprocessesEndothermic第3頁ExothermicHeatFlowHeatflowsoutofthesampleasaresultofeitherHeatcapacity(cooling)CrystallizationCuringOxidationOtherexothermicprocessesExothermic第4頁DSC與DTA測定原理不一樣DSC是在控制溫度變化情況下，以溫度（或時間）為橫坐標，以樣品與參比物間溫差為零所需供應熱量為縱坐標所得掃描曲線。DTA是測量

T-T關(guān)系，而DSC是保持

T=0，測定

H-T關(guān)系。二者最大差異是DTA只能定性或半定量，而DSC成果可用于定量分析。第5頁DSC:WhatDSCCanTellYouGlassTransitions（玻璃化轉(zhuǎn)變，Tg）MeltingandBoilingPoints（熔點和沸點）Crystallizationtimeandtemperature（結(jié)晶時間和溫度）PercentCrystallinity（結(jié)晶度）Polymorphism（多種形態(tài)）HeatsofFusionandReactions（熔化和反應熱）SpecificHeat（比熱）Oxidative/ThermalStability（氧化/熱穩(wěn)定性）RateandDegreeofCure（固化速率和程度）ReactionKinetics（反應動力學）Purity（純度）第6頁DSC:典型DSC轉(zhuǎn)變溫度熱流->放熱玻璃化轉(zhuǎn)變結(jié)晶熔化交聯(lián)(固化)氧化或分解第7頁熱流型(HeatFlux)在給予樣品和參比品相同功率下，測定樣品和參比品兩端溫差

T，然后根據(jù)熱流方程，將T（溫差）換算成Q（熱量差）作為信號輸出。功率賠償型(PowerCompensation)在樣品和參比品始終保持相同溫度條件下，測定為滿足此條件樣品和參比品兩端所需能量差，并直接作為信號

Q（熱量差）輸出。調(diào)制熱流型(ModulatedHeatFlux)在傳統(tǒng)熱流型DSC線性變溫基礎(chǔ)上，疊加一種正弦震蕩溫度程序，最后效果是可隨熱容變化同步測量熱流量，利用傅立葉變換將熱流量即時分解成熱容成份動力學成份。1、DSC基本原理第8頁FurnaceThermocouplesSampleReferencePlatinumAlloyPRTSensorPlatinumResistanceHeaterHeatSink熱流型DSC功率賠償型DSCSample傳統(tǒng)量熱儀內(nèi)部示意圖精確溫度控制和測量更加快響應時間和冷卻速度高辨別率基線穩(wěn)定高敏捷度第9頁

熱流DSC爐子剖面圖DynamicSampleChamberReferencePanSamplePanLidGasPurgeInletChromelDiscHeatingBlockChromelDiscAlumelWireChromelWireThermocoupleJunctionThermoelectricDisc(Constantan)第10頁熱流式DSC-工作原理RsRrTfsTrsTsTr第11頁熱流式DSC-工作原理假設(shè):

1,傳感器絕對對稱，Tfs=Tfr，Rs=Rr=R 2,樣品和參比端熱容相等Cpr-Cps 3,樣品和參比加熱速率永遠相同 4,樣品盤及參比盤質(zhì)量（熱容）相等 5,樣品盤、參比盤與傳感器之間沒有熱阻或熱阻相等

第12頁HeatFluxDSC:TheoreticalDTMeasurementTrTsDTToTpTr=ReferenceTemperatureTs=SampleTemperatureTo=OnsetofMeltTp=PeakofMeltTheoretically:To=TpTimeTemperature第13頁ActualHeatFluxDataSlopeduetothermallagDT第14頁ViolationsofAssumptionsPanandcalorimeterheatcapacitiesareignoredSampleandreferenceheatcapacitiesareassumedtobethesameandtoheatatthesamerate.Ingeneralthesampleandreferencecalorimeterheatcapacitiesdonotmatchcontributingtonon-zeroemptyDSCheatflowratebaseline.DuringtransitionsandMDSC?experimentsthesampleandreferenceheatingratesdifferandthemeasuredheatflowrateisincorrectbecausethesampleandreferencesensorandpanheatcapacitiesstoreorreleaseheatatdifferentrates.第15頁ExpandedPrincipleofOperation

Q=Ts-Tr+A+B+C R

ThermalResistanceImbalance

ThermalCapacitanceImbalance

HeatingRateImbalanceTfsTsRsTfrTrRrCsCrNotBeingMeasuredw/ConventionalDSC第16頁Q-SeriesDSCSchematicSample&ReferencePlatformsTzero?Thermocouple第17頁Q-SeriesHeatFlowMeasurementTrTsRsCsCrRrToTfQ-SeriesDSCTheTzerothermocoupleprovidesan

objectivereferencepointsothatthose

factorspreviouslyassumedcanbedirectly

measured.第18頁Tzero?HeatFlowMeasurementHeatFlowRateEquationsHeatFlowSensorModelThesampleandreferencecalorimeterthermalresistancesandheatcapacitiesobtainedfromTzerocalibrationareusedintheheatflowratemeasurements.DifferentialTemperatures第19頁Tzero?HeatFlowTermContributionsPrincipalheatflowprovidesmainheatflowsignalThermalresistanceandheatcapacityimbalancetermsimprovebaselineHeatingratedifferencetermimprovesresolutionandMDSCperformance第20頁To技術(shù)四相

熱流方程基本熱流熱阻不平衡熱容不平衡加熱速率不平衡標準DSC單項熱流方程To技術(shù)提供額外項第21頁T0及高級T0技術(shù)對DSC測量改善：T0不需假設(shè)（Q200/Q100DSC):

1,傳感器絕對對稱，Tfs=Tfr，Rs=Rr=R 2,樣品和參比端熱容相等Cpr-Cps 3,樣品和參比加熱速率永遠相同高級To不需假設(shè)(Q2023/Q1000DSC)：

4,樣品盤及參比盤質(zhì)量（熱容）性等 5,樣品盤、參比比盤與傳感器之間沒有熱阻或熱阻相等第22頁BaselineBowImprovement第23頁SuperiorResolutiononaPharmaceuticalSampleAnalysis第24頁ResolutionImprovement第25頁AdvancedTzero?Results第26頁MDSC?測量什么?

MDSC將熱流分解成與變化升溫速率有關(guān)和不有關(guān)兩部分MDSC將變化升溫速率疊加在線性升溫速率上是為了測量與變化升溫速率有關(guān)熱流

一般來講,只有熱容與熔融變化與變化升溫速率有關(guān).MDSC可逆和不可逆信號

絕不能

樣品可逆和不可逆性質(zhì)測量

第27頁MDSC?

原理MDSC?

同步采取兩種升溫速率平均升溫速率提供平均升溫速率，它相稱與一般標準DSC@在同樣升溫速率下信號調(diào)制升溫速率目標是為了在得到熱流信號同步得到熱容信號第28頁StandardDSCMeasurestheSumofHeatFlowdH/dt=Cp(dT/dt)+?(T,t)第29頁StandardDSCMeasurestheSumofHeatFlowWhichArisesfromMultipleSourcesdH/dt=Cp(dT/dt)+?(T,t)第30頁IdealSeparationofHeatFlowdH/dt=?(T,t)dH/dt=Cp(dT/dt)第31頁平均&調(diào)制溫度信號調(diào)制溫度平均溫度Modulate+/-0.42°Cevery40secondsRamp4.00°C/minto290.00°C525456586062ModulatedTemperature(°C)525456586062Temperature(°C)13.013.514.014.515.0Time(min)第32頁平均&調(diào)制升溫速率周期平均升溫速率調(diào)制升溫速率0246810Deriv.ModulatedTemperature(°C/min)0246810Deriv.Temperature(°C/min)13.013.514.014.515.0Time(min)第33頁MDSCRawDataSignals…ModulatedHeatFlow

andModulatedTemperature(HeatingRate)Signalshavean“Average”andan“Amplitude”第34頁調(diào)制DSC總熱流：調(diào)制熱流傅立葉轉(zhuǎn)換第35頁CalculationofReversingCpModulatedHeatingRateModulatedHeatFlowReversingCp第36頁調(diào)制DSC?

不一樣成份概念MDSC?DataSignals可逆熱流ReversingTransitions熱容HeatCapacity玻璃化轉(zhuǎn)變GlassTransition大部分熔融MostMelting總熱流=可逆熱流+不可逆熱流第37頁MDSC?DataSignals總熱流=可逆熱流+

不可逆熱流不可逆轉(zhuǎn)變熱焓松弛EnthalpicRecovery揮發(fā)Evaporation結(jié)晶Crystallization熱固化ThermosetCure蛋白質(zhì)變性ProteinDenaturation淀粉糊化StarchGelatinization分解Decomposition部分熔融SomeMelting調(diào)制DSC?不一樣成份概念第38頁MDSC?無定形PETNonreversingReversingTotal-0.4-0.20.0NonrevHeatFlow(W/g)-0.4-0.20.00.20.4RevHeatFlow(W/g)-0.4-0.20.00.2HeatFlow(W/g)050100150200250300Temperature(°C)ExoUp第39頁何時&為何運行MDSC?？我需要比熱信息嗎？轉(zhuǎn)變是一種比熱有關(guān)現(xiàn)象嗎?有被其他效應掩蓋現(xiàn)象嗎？存在對于標準DSC來講很薄弱或很寬轉(zhuǎn)變嗎？是否需要更高敏捷度或辨別率嗎？比熱會在恒溫條件下伴隨時間而變化嗎（例如恒溫固化）？第40頁何時&為何運行MDSC?？對于熔融和結(jié)晶–假如熔融過程看起來正常(單個吸熱峰)并且在加熱時無顯著結(jié)晶

，就無須采取MDSC然而,假如熔融過程很復雜,或很難確定樣品是否在加熱時

存在結(jié)晶,采取MDSC假如想得到比熱(Cp)–運行MDSC通過常規(guī)DSC得到比熱(Q1000由于直接比熱測量是個例外)采取較高升溫速率,>10°C/min需要三個試驗基線參照樣(藍寶石)樣品第41頁一般DSC不足不也許在單個DSC試驗中同步提升敏捷度和辨別率升溫速率快，敏捷度提升，辨別率下降升溫速率慢，辨別率提升，敏捷度下降MDSC?能夠處理該問題是由于他有兩個升溫速率基線彎曲度和漂移限制了DSC檢測弱轉(zhuǎn)變敏捷度MDSC?消除了基線彎曲度和漂移是在于熱容信號取得是采取如下等式:

K

x調(diào)制升溫速率振幅調(diào)制熱流振幅Cp=平均升溫速率

xCp可逆熱流=第42頁圖譜很難解釋由于DSC測量是總熱流MDSC?不但僅提供總熱流，并且包括熱容信號和動力學組分4.

很難通過一般DSC精確測量聚合物結(jié)晶度.

精確測量結(jié)晶度，需要:確定真正熱容基線定量測量在加熱過程中有多少結(jié)晶在繼續(xù)發(fā)展第43頁Application

HeatCapacity

GlassTransitionMeltingandCrystallizationThermoplasticsThermosets

AdditionalApplicationsExamples第44頁假如我們要用DSC測量比熱怎么辦？當f(x)=0時（沒有動力學有關(guān)現(xiàn)象時）。樣品熱流可簡寫為：Q=Cp·

·m

。通過兩次不一樣加熱速率對樣品進行測試即可得到：K為儀器校正系數(shù)1、Cp測量第45頁傳統(tǒng)DSC測量樣品比熱Cp首先需要確定K值。能夠通過已知比熱標準材料（如藍寶石）來確定。

基線重現(xiàn)性對Cp測量影響必須考慮。為了得到更加好Cp數(shù)據(jù)首先要測試空白基線，然后對每次樣品測試成果進行基線扣除。

不要忘掉我們在進行熱流計算時假設(shè)條件。這是測量誤差起源之一。K為儀器校正系數(shù)第46頁傳統(tǒng)

DSC測量比熱辦法

:第47頁DirectCpMeasurementonQ2023/Q1000UnlikeanyotherDSC,theheatflowsignaloftheQ2023/Q1000isanabsolutesignal:BaselineisflatAbsolutezeroheatflowvalueestablishedaspartofmethodByknowingabsolutevaluesoftheheatflowandtheheatingrate,heatcapacityiscalculatedinrealtimeandstoredindatafileAccuracyandprecisionisgenerally±1-2%withjustsinglerunmeasurements第48頁HeatFlowandHeatCapacityfromtheSameExperimentPolypropylene第49頁ItIsOftenDifficulttoIdentifytheTrueBaseline

UsingOnlyHeatFlow第50頁HeatCapacitySignalsAreNormalizedforHeatingRateandPermitComparisonofExperimentsatDifferentHeatingRatesRemember,DSCandMDSCCpsignalsarereallyApparentCpsignals;

crystallizationandmeltingarelatentheats,notCp第51頁EffectofSideChainsonCpPolymerSideChainCp(J/g/°C)PE-H2.763PP-CH2.752PS-Ph2.139Asthestericbulkofthesidechainincreases,molecularmobilitydecreasesresultinginlowerspecificheat.B.Wunderlich,ATHASCpDataBank,1985.第52頁EffectofPolymerBackboneonCp#ofMethylenesCp(J/g/°C)10.622620.691830.708840.759780.7736OCH2n)O([]Asthenumberofmethylenesincrease,mobilityisincreasedinthepolymer,resultinginhigherheatcapacity.B.Wunderlich,ATHASCpDataBank,1985.Polyoxyalkenes@-153°C第53頁EffectofCopolymerCompositiononCpCompositionCopolymerCp(%PP)(Type)(J/°C/mol)6.0block15.127.5random16.3915.5random18.54AsPPconcentrationisincreased,thenumberofmethylenesincreases,resultinginariseinspecificheatcapacity.Also,withrandomnesscomesentropy（熵）,increaseinmobility,andincreaseinspecificheatcapacity.B.Wunderlich,ATHASCpDataBank,1985.PE/PPCopolymer@-93°C第54頁2GlassTransitiondQ/dtdQ/dt溫度溫度TgTg

1/2從DSC曲線上確定Tg辦法第55頁PMMA1stHeatPMMA-Aged1stHeat@10°C/min6.87mgEnthalpicRecoveryPeak122.42°C(H)-0.6-0.4-0.20.0HeatFlow(W/g)406080100120140160Temperature(°C)

ExoUpUniversalV4.2DTAInstruments第56頁PMMA2ndHeatPMMA-Aged2ndHeat@10°C/min6.87mg121.52°C(H)-0.6-0.4-0.20.0HeatFlow(W/g)406080100120140160Temperature(°C)

ExoUp第57頁ComparisonPMMA1stHeat&2ndHeatPMMA-Aged1stHeat@10°C/min6.87mgEnthalpicRecoveryPeakPMMA-Aged2ndHeat@10°C/min6.87mg-0.6-0.4-0.20.0HeatFlow(W/g)406080100120140160Temperature(°C)ExoUpUniversalV4.2DTAInstruments第58頁EnthalpyRelaxation/RecoveryatTgEnthalpyrelaxation,oraging,istheprocessofamorphousmaterialapproachingequilibrium(neverreached).EnergyisreleasedasafunctionoftimeandtemperatureEnthalpyrecoveryistheendothermictransitionseenattheendofaglasstransitioninDSCexperiments.ItistherecoveryofenergythatwasdissipatedduringagingIntraditionalDSC,enthalpyrecoverycanappearasameltandmakemeasurementofTgdifficultSinceenthalpyrecoveryisakineticevent,itcanbeseparatedfromthechangeinheatcapacitybyMDSC第59頁第60頁PracticalSignificanceofEnthalpyRecoveryIsenthalpyrecoveryattheglasstransitionimportant?Sometimes!Iftwosamplesoffinishedproducthavesignificantlydifferentsizeenthalpyrecoverypeaks(differby0.5J/gormore),theycanbeexpectedtoshowdifferencesinsomephysicalproperties(size,hardness,impactresistance,etc.)DifferencesinthesizeoftheenthalpyrecoverypeakforrawmaterialsthatwillbeprocessedattemperaturesaboveTgarenotimportantThethermalhistoryofrawmaterialsisusuallynotcontrolledThesesamplesshouldbecomparedaftertheyareheatedtoatemperatureaboveTgwhichremovesthepreviousthermalhistory第61頁MDSCSeparationofEnthalpyRecoveryPeakTotalHeatFlowincludesTgandenthalpyrecoverypeakReversingHeatFlowcontainsonlyTgNonreversingHeatFlowcontainsenthalpyrecoverypeak第62頁Tg在哪里?藥片,44%RH3.08mgMDSC?1/60/5Tg在哪里?第63頁Tg在這里!Tg在這里!第64頁復雜樣品QuenchedXenoy14.79mg10°C/min復雜樣品第65頁MDSC?

有助于圖譜解釋MDSC?

有助于圖譜解釋第66頁無定形態(tài)PET/PCDSC，PCTg在哪里?第67頁MDSC在聚合物共混物中顯示兩個Tg

MDSC?.318/40/3第68頁DSC@5°C/minforDrugMicrospheresPolymer70%CrystallineDrug15%AmorphousDrug15%Approx.Composition第69頁MDSC?@2°C/minforDrugMicrospheres第70頁聚合物合金一般DSC淬冷PET/PC/HDPE第71頁聚合物合金MDSC?

MeltingofPETMeltingofHDPEZoominonthisarea第72頁聚合物MDSC?TgofPETTgofPCCrystallizationofPETMeltingofHDPE第73頁小甜品在冷卻過程中玻璃化轉(zhuǎn)變

第74頁InterpretingChangeinStructure

forDrugMonohydrateCpofFirstHeatCpofSecondHeatLossofcrystallinityondehydrationRecrystallizationGlassTransitionSampleanalyzedinpinholepan第75頁3、ThermosetMaterialsA“thermoset”isacross-linkedpolymerformedbyanirreversibleexothermicchemicalreactionAcommonexampleisa2partepoxyadhesiveWithaDSCwecanlookatthecuringofthesematerials,andtheTgoffullorpartiallycuredsamples第76頁ThermosettingPolymersThermosettingpolymersreact(cross-link)irreversibly.A+Bwillgiveoutheat(exothermic)whentheycross-link(cure).Aftercoolingandreheating,

CwillhaveonlyaglasstransitionTg.A+BCGLUEThermosetMaterials第77頁CuringofaThermosettingMaterialbyDSC116.07°C76.30°C195.0J/g20MinEpoxyCuredinDSC15.15mg@10°C/min-6-4-202468HeatFlow(mW)050100150200Temperature(°C)DSCExoUpUniversalV4.3ATAInstruments第78頁EffectofHeatingRateonThermosetCuring第79頁殘余固化隱藏玻璃化轉(zhuǎn)變10.85mgEpoxyheating@3°/min,afterisothermalcureat100°C第80頁AdvantageofMDSCforPostCureScanSample:EpoxySize:10.85mgHeatingExperimentat3

C/minAfter160minIsothermalCureat100

CNoteOnsetofDecompositionBeforeCompleteCureNoteInabilitytoMeasureTg第81頁1、掃描速度影響敏捷度隨掃描速度提升而增加辨別率隨掃描速度提升而減少技巧：增加樣品量得到所要求敏捷度低掃描速度得到所要求辨別率DSC測試過程中影響原因第82頁掃描速度影響第83頁大適用于測試低程度轉(zhuǎn)變、非均勻試樣峰寬、溫度精確度、辨別率低。要求dT/dt小。小峰尖，辨別率好，對零級反應轉(zhuǎn)變溫度要求平衡值，允許有大dT/dt，

2、樣品尺寸3、氣氛—不能與試樣反應，動態(tài)優(yōu)于靜態(tài)。高傳熱系數(shù)氣體（如H2、He）辨別率高；

低傳熱系數(shù)氣體（如真空）敏捷度高。樣品皿封壓：底面平整、樣品不外露合適樣品量：敏捷度與辨別率折中第84頁樣品粒度與形狀對曲線影響AgNO3DSC曲線

a.原塊狀樣品b.稍研磨樣品c.先熔化冷卻后再測160165.5210bc吸熱放熱aT拉伸過PET

DSC曲線未拉伸PET

DSC曲線第85頁4、選擇合適樣品盤SamplePan:Crimpedvs.HermeticallySealedCrimpedpansarelighter(?23mg)andprovidebettersensitivityandresolutionHermeticaluminumpansareheavier(?55mg)butcanbesealedtopreventlossofvolatilesHermeticstainlesssteelpans(?250mg)permituseoflargesamples(100mg)andhighertemperatures/pressures(2023psig=1.4MPa)Careshouldbetakentokeepthebottomofallpansflattoimproveheattransfer/resolution第86頁SamplePans Typeofpandependson:SampleformVolatilizationTemperaturerangeUselightest,flattestpanpossibleAlwaysusereferencepanofthesametypeassamplepan第87頁HermeticPans(Sealed)HermeticPansareavailablein:Aluminum:<600°C;<3atm(300kPagage)AlodinedA