增塑聚乳酸的热-机械性能表征课件

Thermo-mechanicalcharacterizationofplasticizedPLA:

Isthemiscibilitytheonlysignificantfactor?Polymer47(2006)4676–4682增塑PLA的热机械性能：miscibility是唯一重要因素吗？IntroductionMaterialsandmethodsResultsanddiscussionConclusionAbstractPLAisawidelyusedpolymerwhichhasreceivedmuchattentioninthelastdecadebecauseofitsoriginatingfromrenewableresourcesanditspotentialbiodegradability.PLAfulfilsthepackagingindustry’srequirementsformostoftherigidobjectsbutthepolymerneedstobeplasticizedtobeusedassoftfilms.Inthiswork,agreedplasticizersforfoodcontactweremeltmixedwithL-PLAandthen,theglasstransition,melting,crystallizationandmechanicalpropertiesoftheblendswereinvestigated.TheexperimentalresultswerecomparedtothepredictedresultsfoundthroughempiricalinteractionparametersandFoxequations.Molecularscalemiscibilityisassumedintheamorphousphasewhatevertheplasticizer.ThemobilitygainedbythePLAchainsintheplasticizedblendsyieldscrystallization,whichisthedrivingforceforvariousscalephaseseparations.1.Introduction

ResearchinbiodegradablepolymersInterestingpropertiesandfaultsofPLAPlasticizingofPLA:necessaryandcommonplasticizersNewresearchaboutplasticizersofPLA1.1ResearchinbiodegradablepolymersIncreasedattentioninrecentyears:wideapplicationinenvironmentalfriendlypackaging.Popularandbiodegradablepolymers:PLA（聚乳酸）,PCL(聚已内酯),PBAT（己二酸-对苯二甲酸-丁二酯共聚物）andPHB（聚羟基丁酸酯）.1.2InterestingpropertiesandfaultsofPLA

InterestingpropertiesofPLA:biodegradability,goodmechanicalproperties,andprocessabilityandsoon.FaultsofPLA:lowdeformationatbreakandhighmodulus.LimitedrigidthermoformedpackagingindustryofPLABiodegradablepackagingmaterials1.3PlasticizingofPLA

--commonplasticizersfoodcontactagreedplasticizersorpolymers:poly(hydroxybutyrate)--聚羟基丁酸酯poly(vinylacetate)--聚醋酸乙烯poly(ethyleneoxide)--聚环氧乙烷

polysaccharides--多糖poly(ethyleneglycol)--聚乙二醇citrate--柠檬酸1.4NewresearchaboutplasticizersofPLA

YounesandCohn:microphaseseparationoccursatagivencompositiondependingonthemolecularweightofPEG(1500and35,000g/mol).Huetal.:theglasstransitiontemperatureofPLA–PEG(8000g/mol)followedtheempiricalFoxequationbuttheblendswerenotstableintimeandphaseseparationwasobserved.Nijenhuisetal.:thepoorlong-termstabilityofblendsbetweenPLAandPEGwasduetoslowcrystallizationofPEG.Others:fattyacidesterisagoodplasticizerwithastronghindranceofthecrystallinephasedevelopment.2.Materialsandmethods

2.2BlendingconditionsMachine:Anopenedmixer(Brabender,50EHT)controlledbyalab-StationdrivenbytheBRABENDERSoftwareWinmix.Conditions:Blendingtemperaturewas180℃andblendingtime15minandbladerotationspeedwas30rpm.Sample:20*20*0.8cm32.3.DifferentialscanningcalorimeterMachine:

Perkin–ElmerPyrisDSC;PyrisV3.0softwareunderWindowsNT4.0fordatacollection.Calibration:

IndiumandTin;temperaturerange[+15to+350℃].Pretreatment:

Heatedto200℃for5min.Precision:

±0.5℃.2.4.MechanicalmeasurementsMachine:

MTSSynergieRT1000Loadingspeed:

1mm/minforpurePLAand10mm/minforplasticizedPLA.

3.1

Solubilityparametercalculation

溶度参数的计算

3.2Thermalanalysisofmiscibility

热分析

3.3Mechanicalproperties

机械性能3.1Solubilityparametercalculation溶解度参数的计算

为了估计两种分子的兼容性，有几种方法可以用于计算溶度参数，本文采用Hoy法计算参数δ。溶度参数的确定基于平均分子量。

Interactionparameter(相互作用参数)χ由等式（1）计算得到：(1)B是一个0.3~0.4的常数，符合entropiccomponent，通常非极性体系采用0.34熵？Table2

SolubilityparameterδandinteractionparameterχbetweenPLAandplasticizers（增塑剂）InTable2,δwascalculatedforPLAandplasticizers.Interactionparameterχ

wasobtainedusingEq.(1),withoutentropiccomponentbecauseofthelargepolarity(极性)ofthecomponentused.χ<0.5Miscible;NophaseseparationFig.1.ThermogramsofPLA/plasticizers90/10(w/w)heatedat20℃min-1aftercoolingat20℃min-1Table3

GlasstransitiontemperatureofpurecomponentsandofblendsbetweenPLAandplasticizersFoxequation：Tg——混合体系玻璃化转变温度Tg1，Tg2——组分的玻璃化转变温度w1，w2——组分的质量分数(2)(d)AGM/PLA;(e)DBS/PLA;(f)PBOH/PLATheotherplasticizersdeviatemoreseverelyfromtheFoxrelationandyieldhigherinteractionparametersaswell.However,eventhoughtheseblendsdonotleadtototalmolecularscalemiscibilitybetweenPLAandplasticizers,theycanoffersatisfyingcompatibilityaswillbeassessedbytensiletests.Table5CrystallizationtemperaturesofpurecomponentsandofPLA/plasticizerblendsduringheatingatarateof20℃min-13.3.MechanicalpropertiesTable6

Tensilemodulus(MPa)ofpurePLAandplasticizedPLATable7

Strainatbreak(%)ofpurePLAandplasticizedPLATable8

Stressatbreak(MPa)ofpurePLAandplasticizedPLAFig.3.Tensilemodulusvsglasstransitiontemperatureofplasticizers/PLAblends.4.ConclusionPlasticizersblendedwithPLAloweredtheglasstransitiontemperatureandmodi