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1、ResearchArticleReceived:11May2011Revised:8July2011Accepted:10July2011PublishedonlineinWileyOnlineLibrary:14October2011(wileyonlinelibrary.com)DOI10.1002/pi.3180Effectofannealingonthemicrostructureandmechanicalpropertiesofpolypropylenewithorientedshish-kebabstructureHongweiBai,aHu
2、aDeng,a∗QinZhang,aKeWang,aQiangFu,a∗ZhijieZhangbandYongfengMenbAbstractAnnealingisthoughttobeaneffectivemethodtopromotechainrearrangementinsemicrystallinepolymersandimprovetheirphysicalproperties.However,littleattentionhasbeenpaidtotheannealingofflow-orientedsemicrystallinepolymer
3、sdespiteitsimportanceinpolymerprocessing.Inthiswork,themicrostructuralevolutionofinjection-mouldedpolypropylenewithanorientedshish-kebabstructureuponannealinghasbeenexploredwithdifferentialscanningcalorimetry,small-angleX-rayscatteringandscanningelectronmicroscopy,Fouriertransfor
4、minfraredspectroscopyanddynamicmechanicalanalysis.Theresultsshowthatannealinggivesrisetoachainrearrangementinboththecrystallineandamorphousphases.Accompaniedbythegrowthandperfectingofthekebabs,relaxationoftheinitiallyorientedchainsintheamorphousphaseisobserved.Then,therelationshi
5、pbetweenthestructureandtheresultingmechanicalpropertiesisestablished.c2011SocietyofChemicalIndustryKeywords:polypropylene;shish-kebab;annealing;molecularorientation;toughnessINTRODUCTIONopedinrecentyearstosuppresstherelaxationoftheorientedItiswellknownthatisotacticpolypropylene,
6、oneofthemostim-meltduringcoolingsolidification.Inourgroup,dynamicpack-portantsemicrystallinepolymerswithfastexpansioninmarketinginjectionmoulding(DPIM),atypeofSCORIMtechnique,hasshare,cancrystallizeintotwodistinctcrystallinemorpholo-beensuccessfullyusedtoprepareinjection-mouldedpa
7、rtswithahighlyorientedshish-kebabstructure.24–30Insuchaprocess,angiesfromthemelt:spherulitesandshish-kebabsuperstructure.Isotropicspherulitesareoftenobservedunderquiescentcrystal-oscillatoryshearfieldisimposedonthecoolingpolymermeltslizationconditions,whileanisotropicshish-kebabsc
8、anonlybeduringpackingstagewithtwopistons
