TGA课件.ppt
- 文档编号:30842717
- 上传时间:2024-01-31
- 格式:PPT
- 页数:69
- 大小:6.07MB
TGA课件.ppt
《TGA课件.ppt》由会员分享,可在线阅读,更多相关《TGA课件.ppt(69页珍藏版)》请在冰豆网上搜索。
,热重分析(TGA),Theory&Applications,2,TGA:
TheTechnique,ThermogravimetricAnalysis(TGA)measurestheamountandrateofchangeintheweightofamaterialasafunctionoftemperatureortimeinacontrolledatmosphere.,热重分析的结果用热重曲线或微分热重曲线表示。
样品在热环境中发生化学变化、分解、成分改变时可能伴随着重量的变化。
热重分析就是在不同的热条件(以恒定速度升温或等温条件下延长时间)下对样品的质量变化加以测量的动态技术。
3,WhatTGACanTellYou,ThermalStabilityofMaterialsOxidativeStabilityofMaterialsCompositionofMulti-componentSystemsEstimatedLifetimeofaProductDecompositionKineticsofMaterialsTheEffectofReactiveorCorrosiveAtmospheresonMaterialsMoistureandVolatilesContentofMaterials,热稳定性,氧化稳定性,组成,产品寿命,分解动力学,反应或腐蚀气氛对材料的影响,材料水分和挥发份含量,4,MechanismsofWeightChangeinTGA,WeightLoss:
Decomposition:
Thebreakingapartofchemicalbonds.Evaporation:
Thelossofvolatileswithelevatedtemperature.Reduction:
Interactionofsampletoareducingatmosphere(hydrogen,ammonia,etc).Desorption.WeightGain:
Oxidation:
Interactionofthesamplewithanoxidizingatmosphere.Absorption.Allofthesearekineticprocesses(i.e.thereisarateatwhichtheyoccur).,5,DTG曲线微分型曲线,TG曲线积分型曲线,6,初始热分解温度(B、G),反应终了温度(C、H),最大失重速率温度,7,影响热重测定的因素:
PurgeGas,TGA:
AlwayspurgethroughbalancehousingwithdryinertgasTGA:
Onlyintroducereactive/corrosivegasesthroughsamplearea/furnacehousingNitrogenmostcommon.Heliumoftenprovidesbestbaselinebutwillmakefurnaceworkhardathightemperature.Aircansometimesimproveresolutionbecauseofdifferencesintheoxidativestability(versusthermalstability)ofcomponents.,气氛不同反应机理的不同。
8,TGA:
PurgeGasFlow,60ml/min,90ml/min,10ml/min,40ml/min,StandardFurnace,EGAFurnace,9,TestforOxygenContaminationofN2PurgeGas,320.79C,10minuteN2pre-purge,+,CopperOxalate,10,EffectofOxygenonCopperOxalateDecomposition,11,TGA:
BaselineConsiderations,GoodwaytoquantifyhowtheTGA/SDTisworking.Especiallyimportantformeasuringsmallweightlossesassociatedwithvolatilizationorsmallamountsofresidue.Runclean,empty,taredpan,overtemperaturerangeofinterest,atdesiredheatingrate.Plotweightingvs.temperature.,12,TGA:
AccurateResiduals,13,TGA:
SamplePreparation(cont.),UsebrasstweezerstoeliminatestaticeffectsTareacleansamplepanbeforeeveryrunDistributesampleevenlyoverbottomofpanLiquidsamples-usehermeticpanwithapin-holelid,14,Platinum(usefulformostmaterials)EasytoCleanNonporousAlloyswithmostmetalsAlumina(Ceramic)Corrosives/InorganicsLargesamplesAluminum(TGA)(designedforone-timeuse)LowercostLowertemperaturelimit(=600C),TGA:
SamplePanSelection,15,TGA:
SamplePans-Types/Sizes,16,EffectofSampleSize,17,EffectofHeatingRate,18,MassEffectSemi-crystallinePE,19,PanShapeEffectAmorphousPMMA,20,SampleMorphologyEffectsPET,2.9mg;amorphousPET2.8mg;semi-crystallinePET,21,ShiftinOnsetwithRampRate,22,TimetoCompleteDegradation,23,Q5000IRHigh-HeatingRateTGAAnalysis,24,TypicalApplications,ThermalStabilityCompositionalAnalysisOxidativeStability,25,ThermalStabilityofPolymers,26,BlockversusRandomCopolymers,27,EffectofEpoxyCureTemperature,260,280,300,320,340,360,380,400,420,440,0,20,40,60,80,100,Temperature(C),Weight(%),100C,125C,150C,175C,200C,Prog:
10C/min,28,CuriePoint(居里温度)Determination,29,ThermalStabilityofanExplosiveMaterial,30,ThermalStabilityofanExplosiveMaterial,31,TGAofanAdhesive,25.18mgofanadhesive10C/min,32,InsetViewShowsStrangeResult,Isthisreal?
33,Usetimebasedderivativeoftemperaturetoplottheheatingrate,34,AberrationinHeatingRate,Usuallymeansthatthesampletouchedthethermocouple,35,TGAofDrugA,Sample:
DrugASize:
22.5850mgHeatingRate:
10C/min,36,TGAofDrugAMonohydrate,Sample:
DrugAMonohydrateSize:
15.1740mgHeatingRate:
10C/min,Waterweightloss,Decomposition,37,TGAofDrugAMicrospheres,Sample:
DrugAMicrospheresSize:
14.2940mgHeatingRate:
10C/min,38,TGAAnalysisofCold/AllergyTablet,Sample:
Cold/AllergyTabletSize:
18.4890mgHeatingRate:
10C/min,Volatiles,Decomposition,39,DSC-TGASodiumTungstate,SmallSampleSize(3mg)and10C/minHeatingRate,Dehydration,Solidstateandmeltingtransitions,40,DehydrationSensitivity,41,TGA-DSCSodaAsh,Dehydration,HeatflowIntegrationsautomaticallynormalizedusingweightatstartoftransition,Polymorphicphasetransitions,Meltingtransition,42,CompositionalAnalysisCalciumOxalate,Sample:
CaOxSize:
6.9610mgHeatingRate:
10C/min,43,EVACopolymer,%VinylAcetate=%AceticAcid*MolecularWeight(VA)/MolecularWeight(AA),VA%=16.85(86.1/60.1)=24.2%,Sample:
EVA(25%)Size:
19.2030mgHeatingRate:
10C/min,44,PETw/CarbonBlackFiller,HowmuchCarbonBlackwasinthissample?
45,PET,46,ComparisonofFilled&Un-FilledPET,47,Styrene-ButadieneRubberAnalysis,48,FilledPolymerAnalysis,Inertfiller,Inertfiller,Inertfiller,49,OxidativeStabilityEpoxy,50,ResolutionEnhancementbyChangingPurge,PET,N2AirN2w/switchtoair,gasswitch,51,传统TGA与高分辨TGA之比较聚氨酯,52,传统TGA与高分辨TGA之比较,CharacterizationofaPTFE/PEEK/CarbonFiberBlend,53,DecompositionKineticsBackground,Includesisothermalandconstantheatingratemethods.Constantheatingratemethodisthefastestandwillbediscussedhere.BasedonmethodofFlynnandWallPolymerLetters,19,323,(1966).Requirescollectionofmultiplecurvesatmultipleheatingrates.UltimatebenefitobtainedinLife-Timeplots.,Requiresatleast3TGArunsatdifferentheatingratesor1ModulatedTGArunCalculatesActivationenergy&conversioncurvesUltimatebenefitispredictivecurves“LifetimePlots”,54,KineticAnalysis,Therateatwhichakineticprocessproceedsdependsnotonlyonthetemperaturethespecimenisat,butalsothetimeithasspentatthattemperature.Typicallykineticanalysisisconcernedwithobtainingparameterssuchasactivationenergy(Ea),reactionorder(k),etc.and/orwithgeneratingpredictivecurves.,55,KineticAnalysis,cont.,Activationenergy(Ea)canbedefinedastheminimumamountofenergyneededtoinitiateachemicalprocess.,State1,State2,Ea,WithModulatedTGA,Eacanbemeasureddirectly.,56,TGAKineticsExample,57,TGAKinetics-HeatingRatevs.Temperature,ActivationEnergy(Ea)Slope,58,TGAKinetics-EstimatedLifetime,59,WhyUseEvolvedGasAnalysis?
TGAmeasuresweightchanges(quantitative)Difficulttoseparate,identify,andquantifyindividualdegradationproducts(off-gases)Directcouplingtoidentificationtechniques(MassSpec,FTIR)reducesthisproblem,EvolvedGasAnalysis,60,Mass-SpectrometryBenefits,AdditionalinformationfortheinterpretationofthereactionsintheTGAresultsSensitivemethodfortheanalysisofgaseousreactionproductsExactcontrolofthefurnaceatmospherebeforestartingandduringtheexperimentLocationofairleaksaroundthefurnace,61,TGA-MassSpectroscopy,Advantages:
HighersensitivityandwiderdynamicrangethanFTIR(1ppmvs.10ppm).Measuresnon-IRabsorbinggases.Morerapidresponse.Disadvantage:
Cannotdistinguishbetweenisomers.(e.g.N2andCO),62,TGA-FTIR,FTIRAdvantages:
On-linemeasurementHydrocarbonsareeasytoidentifyDisadvantages:
Nodetectionofinertgases(nodipolemoment)Detectionofinorganicgaseslimited,63,TGA-MS:
SystemSchematic,64,TGAofCalciumOxalate,65,TGA-MSCalciumOxalate,66,TGA-MS,67,TGA-MS,Duringweightloss,areactionoccursbetweenH2inpurgeandsampleinwhichH2OandHOareproduced.,68,TGA-MS,Benzeneisacomponentofsmoke.Muchreducedintheflameretardantsample.,69,CompositionalAnalysisbyTGA-MS,
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- TGA 课件