1、1Differential Scanning Calorimetry (DSC)Theory & Applications2整 体 概 述THE FIRST PART OF THE OVERALL OVERVIEW, P L E A S E S U M M A R I Z E T H E C O N T E N T第一部分3差示扫描量热仪 (DSC)nDSC测量样品吸热和放热与温度或时间的关系吸热 热流入样品，即样品吸收外界热量，为负值。放热 热流出样品，即样品对外界放出热量，为正值。国际标准ISO 11357-1:： DSC就是测量在程序控制温度下，输入到试样和参比物之间的功率差（dH/dt
2、）与温度(T)的关系的一种技术。该热流差能反映样品随温度或时间变化所发生的焓变：样品吸收能量时，焓变为吸热；当样品释放能量时，焓变为放热。4-0.4-0.3-0.2-0.10.00.1Heat Flow (W/g)0255075100125150Temperature (C)Exo UpEndothermic Heat FlowlHeat flows into the sample as a result of either lHeat capacity (heating) lGlass Transition (Tg)lMeltinglEvaporationlOther endothermic
3、 processesEndothermic5-0.10.00.1Heat Flow (W/g)020406080100120140160Temperature (C)Exo UpExothermic Heat FlowlHeat flows out of the sample as a result of either lHeat capacity (cooling) lCrystallizationlCuringlOxidationlOther exothermic processesExothermic6DSC与DTA测定原理的不同lDSCDSC是在控制温度变化情况下，以温度（或时间）为横
4、坐标，以样品与参比物间温差为零所需供给的热量为纵坐标所得的扫描曲线。lDTADTA是测量 T-T T-T 的关系，而DSCDSC是保持 T = T = 0 0，测定 H-T H-T 的关系。两者最大的差别是DTADTA只能定性或半定量，而DSCDSC的结果可用于定量分析。7DSC: What DSC Can Tell YoulGlass Transitions（玻璃化转变，Tg）lMelting and Boiling Points（熔点和沸点）lCrystallization time and temperature（结晶时间和温度）lPercent Crystallinity（结晶度）lP
5、olymorphism（多种形态）lHeats of Fusion and Reactions（熔化和反应热）lSpecific Heat（比热）lOxidative/Thermal Stability（氧化/热稳定性）lRate and Degree of Cure（固化速率和程度）lReaction Kinetics（反应动力学）lPurity（纯度）8DSC: 典型 DSC 转变温度热流 - 放热玻璃化转变结晶熔化交联 (固化) 氧化 或分解9热流型(Heat Flux)(Heat Flux)在给予样品和参比品相同的功率下，测定样品和参比品两端的温差 T T，然后根据热流方程，将 T T
6、（温差）换算成 Q Q（热量差）作为信号的输出。功率补偿型(Power Compensation)(Power Compensation)在样品和参比品始终保持相同温度的条件下，测定为满足此条件样品和参比品两端所需的能量差，并直接作为信号 Q Q（热量差）输出。调制热流型(Modulated Heat Flux)(Modulated Heat Flux)在传统热流型DSCDSC线性变温基础上，叠加一个正弦震荡温度程序，最后效果是可随热容变化同时测量热流量，利用傅立叶变换将热流量即时分解成热容成分动力学成分。1、DSC的基本原理FurnaceThermocouplesSampleReferenc
7、ePlatinum AlloyPRT SensorPlatinumResistance HeaterHeat Sink热流型 DSC功率补偿型 DSCSample传统量热仪内部示意图精确的温度控制和测量更快的响应时间和冷却速度高分辨率基线稳定高灵敏度 热流DSC 炉子剖面图Dynamic Sample ChamberReference PanSample PanLidGas Purge InletChromel DiscHeating BlockChromel DiscAlumel WireChromel WireThermocouple JunctionThermoelectric Disc
8、 (Constantan)12热流式 DSC - 工作原理sfsssRTTQrfrrrRTTQrsQQQRsRrTfsTrsTsTrRrTTRTTQQQfrrsfssrs13热流式 DSC - 工作原理假设: : 1, 1, 传感器绝对对称，Tfs = TfrTfs = Tfr， Rs = Rr = R Rs = Rr = R2, 2, 样品和参比端的热容相等Cpr-CpsCpr-Cps3, 3, 样品和参比的加热速率永远相同4, 4, 样品盘及参比盘的质量（热容）相等5, 5, 样品盘、参比盘与传感器之间没有热阻或热 阻相等 RTRTTRTTTTRrTTRTTQQQrsfrrfssfrrsf
9、ssrs14Heat Flux DSC: Theoretical T MeasurementTrTsTToTpTr = Reference TemperatureTs = Sample TemperatureTo = Onset of MeltTp = Peak of MeltTheoretically: To = TpTimeTemperature15Actual Heat Flux Data-4-20Delta T/Heat Flow156.0156.5157.0157.5Reference Temperature (C)156.0156.5157.0157.5SampleTemperat
10、ure (C)5.25.35.45.55.65.75.8Time (min)Sample: Indium +2C/minSize: 1.7900 mgComment: Multiple Heating and Cooling RatesDSCFile: .TADataDSCShickIndium 5.018Operator: CaulfieldRun Date: 08-Sep-2006 16:51Instrument: DSC Q1000 V9.6 Build 290Exo UpSlope due to thermal lagT16Violations of AssumptionsPan an
11、d calorimeter heat capacities are ignored Sample and reference heat capacities are assumed to be the same and to heat at the same rate. In general the sample and reference calorimeter heat capacities do not match contributing to non-zero empty DSC heat flow rate baseline. During transitions and MDSC
12、 experiments the sample and reference heating rates differ and the measured heat flow rate is incorrect because the sample and reference sensor and pan heat capacities store or release heat at different rates.17Expanded Principle of Operation Q = Ts - Tr + A + B + C R ThermalResistance Imbalance The
13、rmalCapacitance Imbalance Heating RateImbalanceTfsTsRsTfrTrRrCsCrNot Being Measured w/ Conventional DSC18Q-Series DSC SchematicSample & Reference PlatformsTzero ThermocoupleConstantan BodyChromel WireChromel Area DetectorConstantan WireChromel WireBase SurfaceThin Wall TubeSample PlatformReference P
14、latformQ-Series Heat Flow MeasurementTrTsRsCsCrRrToTfQ-Series DSCThe Tzero thermocouple provides anobjective reference point so that thosefactors previously assumed can be directlymeasured.20Tzero Heat Flow Measurement Rs Rr qs qr Cs Cr Tr T0 Ts Heat Flow Rate EquationsHeat FlowSensor ModelThe sampl
15、e and reference calorimeter thermal resistances and heat capacities obtained from Tzero calibration are used in the heat flow rate measurements.rsTTTsTTT00dtdTCRTqsss0dtdTCRTTqrrr0Differential Temperatures21Tzero Heat Flow Term ContributionslPrincipal heat flow provides main heat flow signallThermal
16、 resistance and heat capacity imbalance terms improve baselinelHeating rate difference term improves resolution and MDSC performancedTdCddTCCRRTRTqrssrrsr11022To技术的四相 热流方程dTdCddTCCRRTRTqrssrrsr110基本热流热阻不平衡热容不平衡加热速率不平衡标准DSC的单项热流方程To技术提供的额外项23T0及高级T0技术对DSC测量的改进：T0不需假设（Q200/Q100 DSC):1, 传感器绝对对称，Tfs = T
17、fr， Rs = Rr = R2, 样品和参比端的热容相等Cpr-Cps3, 样品和参比的加热速率永远相同高级To不需假设(Q2000/Q1000 DSC)：4, 样品盘及参比盘的质量（热容）性等5, 样品盘、参比比盘与传感器之间没有热阻或热阻相等 dTdCddTCCRRTRTqrssrrsr11024Baseline Bow Improvement25Superior Resolution on a Pharmaceutical Sample Analysis26Resolution Improvement156.81C-8.58mW0.49C156.92C-6.74mW1.03C-8-6-
18、4-202Heat Flow T4 (mW)-8-6-4-202Heat Flow T1 (mW)150152154156158160162164Temperature (C)Sample: Indium +10C/minSize: 1.7900 mgComment: Multiple Heating and Cooling RatesDSCFile: .TADataDSCShickIndium 5.001Operator: CaulfieldRun Date: 08-Sep-2006 12:08Instrument: DSC Q1000 V9.6 Build 290Exo Up27Advan
19、ced Tzero Results6165697377Temperature (C)-25-20-15-10-50Heat Flow (mW)Advanced TzeroTzero DSCConventional DSCAdvanced Tzero DSC 1.13 mg Dotriacontane 10C/min28MDSC 测量什么? lMDSC 将热流分解成与变化的升温速率相关和不相关的两部分lMDSC将变化的升温速率叠加在线性的升温速率上是为了测量与变化的升温速率相关的热流 l一般来讲, 只有热容与熔融的变化与变化的升温速率相关.lMDSC 的可逆和不可逆信号 绝不能 样品可逆和不可逆
20、性质的测量29MDSC 原理lMDSC 同时采用两种升温速率l平均升温速率l提供平均升温速率，它相当与普通标准 DSC 在同样升温速率下的信号l调制升温速率l目的是为了在得到热流信号的同时得到热容的信号30Standard DSC Measures the Sum of Heat FlowdH/dt = Cp(dT/dt) + (T,t)31Standard DSC Measures the Sum of Heat Flow Which Arises from Multiple SourcesdH/dt = Cp(dT/dt) + (T,t)32Ideal Separation of Heat
21、 FlowdH/dt = (T,t)dH/dt = Cp(dT/dt)33平均 & 调制温度信号调制温度平均温度Modulate +/- 0.42 C every 40 secondsRamp 4.00 C/min to 290.00 C525456586062Modulated Temperature (C)525456586062Temperature (C)13.013.514.014.515.0Time (min)34平均 & 调制升温速率周期平均升温速率调制升温速率0246810Deriv. Modulated Temperature (C/min)0246810Deriv. Tem
22、perature (C/min)13.013.514.014.515.0Time (min)35MDSC Raw Data SignalsModulated Heat Flow and Modulated Temperature (Heating Rate)36调制DSC总热流：调制热流的傅立叶转换37Calculation of Reversing CpModulated Heating RateModulated Heat FlowReversing Cp38调制DSC 不同成分的概念lMDSC Data Signalst)(T, dtdT Cp dtdHf可逆热流Reversing Tr
23、ansitions热容Heat Capacity玻璃化转变Glass Transition大部分的熔融Most Melting 总热流 = 可逆热流 + 不可逆热流39lMDSC Data Signalst)(T, dtdT Cp dtdHf 总热流 = 可逆热流 + 不可逆热流不可逆转变热焓松弛Enthalpic Recovery挥发Evaporation结晶Crystallization热固化Thermoset Cure蛋白质变性Protein Denaturation淀粉糊化Starch Gelatinization分解Decomposition部分熔融Some Melting调制DSC
24、 不同成分的概念40MDSC 无定形 PETNonreversingReversingTotal-0.4-0.20.0Nonrev Heat Flow (W/g)-0.4-0.20.00.20.4Rev Heat Flow (W/g)-0.4-0.20.00.2Heat Flow (W/g)050100150200250300Temperature (C)Exo Up41何时 & 为什么运行 MDSC？l我需要比热信息吗？l转变是一个比热相关的现象吗?l有被其他效应掩盖的现象吗？l存在对于标准DSC来讲很微弱或很宽的转变吗？l是否需要更高的灵敏度或分辨率吗？l比热会在恒温条件下随着时间而变化吗
25、（比如恒温固化）？42何时 & 为什么运行 MDSC？l对于熔融和结晶 l如果熔融过程看起来正常 (单个吸热峰) 并且在加热时无明显的结晶 ，就不必采用 MDSCl然而, 如果熔融过程很复杂, 或很难确定样品是否在加热时 存在结晶, 采用MDSC l如果想得到比热 (Cp) 运行MDSCl通过常规DSC得到比热 (Q1000 由于直接比热的测量是个例外)l采用较高的升温速率, 10C/minl需要三个实验基线参考样 (蓝宝石)样品43普通 DSC的局限性不可能在单个DSC的实验中同时提高灵敏度和分辨率升温速率快，灵敏度提高，分辨率下降升温速率慢，分辨率提高，灵敏度下降MDSC 可以解决该问题是
26、因为他有两个升温速率基线弯曲度和漂移限制了DSC检测弱转变的灵敏度MDSC 消除了基线弯曲度和漂移是在于热容信号的取得是采用如下等式:K x 调制升温速率振幅调制热流振幅Cp平均升温速率 x Cp可逆热流44图谱很难解释l因为DSC测量的是总热流lMDSC 不仅仅提供总热流，而且包括热容的信号和动力学组分4. 很难通过普通DSC准确测量聚合物的结晶度. l准确测量结晶度，需要:l确定真正的热容基线l定量测量在加热过程中有多少结晶在继续发展45ApplicationHeat Capacity Glass TransitionMelting and CrystallizationThermopla
27、stics ThermosetsAdditional Applications Examples46t)(T,dtdT Cp dtdHf如果我们要用DSC测量比热怎么办？当f(x)=0 时（没有动力学相关现象时）。样品热流可简写为：Q = Cp m 。通过两次不同加热速率对样品进行测试即可得到：mQQKCp)(2121K为仪器校正系数1、Cp的测量47传统DSC测量样品比热Cp首先需要确定K值。 可以通过已知比热的标准材料（如蓝宝石）来确定。 基线的重现性对Cp测量影响必须考虑。 为了得到更好的Cp数据首先要测试空白基线，然后对每次样品 测试结果进行基线扣除。 不要忘记我们在进行热流计算时的假
28、设条件。这是测量误差的来源之一。mQQKCp)(2121K为仪器校正系数48传统 DSC 测量比热的方法 :49Direct Cp Measurement on Q2000/Q1000Unlike any other DSC, the heat flow signal of the Q2000/Q1000 is an absolute signal:l Baseline is flatl Absolute zero heat flow value established as part of methodBy knowing absolute values of the heat flow a
29、nd the heating rate, heat capacity is calculated in real time and stored in data fileAccuracy and precision is generally 1-2% with just single run measurements50Heat Flow and Heat Capacity from the Same ExperimentPolypropylene51It Is Often Difficult to Identify the True Baseline Using Only Heat Flow
30、52Heat Capacity Signals Are Normalized for Heating Rate and Permit Comparison of Experiments at Different Heating RatesRemember, DSC and MDSC Cp signals are really Apparent Cp signals; crystallization and melting are latent heats, not Cp53Effect of Side Chains on CpPolymerSide ChainCp (J/g/C)PE-H2.7
31、63PP-CH2.752PS-Ph2.139As the steric bulk of the side chain increases, molecular mobility decreases resulting in lower specific heat.B. Wunderlich, ATHAS Cp Data Bank, 1985. 54Effect of Polymer Backbone on Cp# of MethylenesCp (J/g/C)10.622620.691830.708840.759780.7736OCH2n)O(As the number of methylen
32、es increase, mobility isincreased in the polymer, resulting in higher heat capacity.B. Wunderlich, ATHAS Cp Data Bank, 1985. Polyoxyalkenes -153CEffect of Copolymer Composition on CpCompositionCopolymerCp(%PP)(Type)(J/C/mol)6.0block15.127.5random16.3915.5random18.54As PP concentration is increased,
33、the number of methylenesincreases, resulting in a rise in specific heat capacity. Also, with randomness comes entropy（熵 ）, increase in mobility, and increasein specific heat capacity.B. Wunderlich, ATHAS Cp Data Bank, 1985. PE/PP Copolymer -93C562 Glass Transitiond Q/dtd Q/dt温度温度TgTg 1/2 从DSC曲线上确定Tg
34、的方法57PMMA 1st HeatPMMA - Aged1st Heat 10C/min6.87 mgEnthalpic Recovery Peak122.42C(H)-0.6-0.4-0.20.0Heat Flow (W/g)406080100120140160Temperature (C) Exo UpUniversal V4.2D TA Instruments58PMMA 2nd HeatPMMA - Aged2nd Heat 10C/min6.87 mg121.52C(H)-0.6-0.4-0.20.0Heat Flow (W/g)406080100120140160Temperat
35、ure (C) Exo Up59Comparison PMMA 1st Heat & 2nd HeatPMMA - Aged1st Heat 10C/min6.87 mgEnthalpic Recovery PeakPMMA - Aged2nd Heat 10C/min6.87 mg-0.6-0.4-0.20.0Heat Flow (W/g)406080100120140160Temperature (C)Exo UpUniversal V4.2D TA Instruments60Enthalpy Relaxation/Recovery at TglEnthalpy relaxation, o
36、r aging, is the process of amorphous material approaching equilibrium (never reached). Energy is released as a function of time and temperaturelEnthalpy recovery is the endothermic transition seen at the end of a glass transition in DSC experiments. It is the recovery of energy that was dissipated d
37、uring aginglIn traditional DSC, enthalpy recovery can appear as a melt and make measurement of Tg difficultlSince enthalpy recovery is a kinetic event, it can be separated from the change in heat capacity by MDSC6162Practical Significance of Enthalpy RecoverylIs enthalpy recovery at the glass transi
38、tion important?lSometimes!lIf two samples of finished product have significantly different size enthalpy recovery peaks (differ by 0.5 J/g or more), they can be expected to show differences in some physical properties (size, hardness, impact resistance, etc.)lDifferences in the size of the enthalpy
39、recovery peak for raw materials that will be processed at temperatures above Tg are not importantlThe thermal history of raw materials is usually not controlledlThese samples should be compared after they are heated to a temperature above Tg which removes the previous thermal history63MDSC Separatio
40、n of Enthalpy Recovery PeakTotal Heat Flow includes Tg and enthalpy recovery peakReversing Heat Flow contains only TgNonreversing Heat Flow contains enthalpy recovery peak64Tg在哪里?药片, 44%RH 3.08mg MDSC 1/60/5Tg在哪里?65Tg在这里!Tg在这里!66复杂样品Quenched Xenoy 14.79mg 10C/min复杂样品67MDSC 有助于图谱解释MDSC 有助于图谱解释68无定形态
41、PET/PC的DSC， PC的Tg在哪里 ?120.00C170.00C30.74J/g215.00C270.00C42.95J/g120.00C270.00C13.31J/gStandard DSC 10C/min57% PET; 43% PCDSC Heat Flow AnalyzedTwo Different Ways-16-12-8-404 Heat Flow (mW)-22-18-14-10-6-2Heat Flow (mW)50100150200250Temperature (C)Sample: Quenched PET and PCSize: 13.6000 mgMethod:
42、DSC10Comment: DSC10; PET13.60/PC 10.40/Al film 0.96mgDSCFile: C:.LenCrystallinityqPET-PCdsc.001Exo UpUniversal V3.8A TA Instruments69MDSC 在聚合物共混物中显示两个 Tg Decrease in Heat CapacityDue to Cold CrystallizationGlass Transitionof PolycarbonateTrue Onset of MeltingCold Crystallization PeakSeen Only in Tot
43、al SignalTotal Heat FlowReversing Heat Flow-3.2-3.0-2.8-2.6-2.4-2.2-2.0 Rev Heat Flow (mW)-3.2-3.0-2.8-2.6-2.4-2.2-2.0Heat Flow (mW)50100150200250Temperature (C)Sample: Quenched PET and PCSize: 13.6000 mgMethod: MDSC .318/403Comment: MDSC 0.318/403; PET13.60/PC 10.40/Al film 0.96mgDSCFile: C:TADataL
44、enCrystallinityqPET-PC.002Exo UpUniversal V3.8A TA InstrumentsMDSC .318/40/370Polymer 70% Crystalline Drug 15% Amorphous Drug 15%Approx. Composition71MDSC 2C/min for Drug Microspheres72聚合物合金的普通DSC-5-4-3-2-1Heat Flow (mW)50100150200250300Temperature (C) Exo UpUniversal V4.2D TA Instruments淬冷 PET/PC/H
45、DPE73聚合物合金的MDSC -1.5-1.0-0.50.0Nonrev Heat Flow (W/g)-2.0-1.5-1.0-0.50.0Rev Heat Flow (W/g)-2.5-2.0-1.5-1.0-0.50.0Heat Flow (W/g)50100150200250300Temperature (C) Exo UpUniversal V4.2D TA InstrumentsMelting of PETMelting of HDPEZoom in on this area74聚合物的MDSC75.63C(H)145.78C(H)-0.6-0.4-0.20.00.20.4Non
46、rev Heat Flow (W/g)-1.2-1.0-0.8-0.6-0.4-0.20.00.2Rev Heat Flow (W/g)-1.4-1.2-1.0-0.8-0.6-0.4-0.20.0Heat Flow (W/g)6080100120140160180Temperature (C) Exo UpUniversal V4.2D TA InstrumentsTg of PETTg of PCCrystallization of PETMelting of HDPE75小甜品在冷却过程中的玻璃化转变 76Interpreting Change in Structure for Drug
47、 MonohydrateCp of First HeatCp of Second HeatLoss of crystallinity on dehydrationRecrystallizationGlass TransitionSample analyzed in pinhole pan773、Thermoset MaterialslA “thermoset” is a cross-linked polymer formed by an irreversible exothermic chemical reactionlA common example is a 2 part epoxy ad
48、hesivelWith a DSC we can look at the curing of these materials, and the Tg of full or partially cured samples78Thermosetting PolymersThermosetting 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
49、a glass transition Tg.A + B CGLUEThermoset Materials79Curing of a Thermosetting Material by DSC116.07C76.30C195.0J/g20 Min Epoxy Cured in DSC15.15mg 10C/min-6-4-202468Heat Flow (mW)050100150200Temperature (C)DSCExo UpUniversal V4.3A TA Instruments80Effect of Heating Rate on Thermoset Curing128.29C0.
50、5594W/g122.26C323.9J/g137.04C0.9506W/g130.12C315.5J/g149.93C1.972W/g141.85C315.1J/g160.93C3.431W/g151.92C320.0J/g172.86C5.792W/g162.53C320.5J/g-20246Heat Flow T4 (W/g)100120140160180200220240Temperature (C)1C/min2C/min5C/min10C/min20C/min81残余固化隐藏玻璃化转变10.85 mg Epoxy heating 3/min, after isothermal cu
