等规聚丙烯在流动场中的非线性流变行为与其对结晶的影响

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1、AbstractInpolymermaterialprocessing，externalflowfieldinducesthechangeofchainconformationanddifferenceofrheobgmalbehaviors，whichleadtovariationofcombinationpathascrystallization．Tounderstandflow-inducedcrystallizationr℃edstheclearpointofrelationshipanaongexternalflowfield，polymerrheologic

2、albehaviorandcrystallization．Whilepolymermeltisalmostinnonlinearrheobgmalmgmninprocessing．Localflowfieldperhaps1a]rgelydiffers舶mapparentconditionduetoinstabilityofflow,whichmakesrelationshipbetweenflowfieldandcrystallizationmorecomplicated．Shearthinningisalwaysinahomogenouswayunderexterm

3、lflowwhilewallsnp，shearbandinganddelayedfractureoftenoccurd啊ingbothexperimentsandindustrialprocessinginheterogeneousways．ThecorrelationbetweenthesenonlinearrheologicalbehaviorsandcrysmllizationIllakesusunderstandindepthandprovidemuchmorewaystoconlrolexternalconditiontoacquireidealsamples

4、／pinducts．Recentobservationsofshearbandmganddelayedfractureinentangledpolymernquidhaveatlractedagreatdealofattentioninpolymercommunity,whichchallengeourcurrentunderstandingofpolymerdynamics．Thoughtheinterpretationonsuchnon-linearbehaviorsisstillamatterofdebate，theobservationshavebeenconf

5、irmedbydiffemntgroups(includingotlrgro印)．Animmediatequestionisraisedup：howdosuchnen-linearrheologicalbehaviorsaffectflow—inducedcrystallization(FIC)ofp01yIner9InthestudyofFICofpolymer,ahomogeneousflow毹ldisgenerallyassumedandran-linearrheologicalbehaviorslikeshearbandinganddelayedfracture

6、havenotbeentakenintoaccount,whichrmyleadstoamismatchbetweenflowfieldandcrystallizationbehavior．Inthisstudy,wecombineparticle—trackingvelocimetry口TV)andsynchrolronradiationmicrobeamwideangleX—raydiffraction(SR％tWAXD)tostudyFICofisotacticpolypropylene．Interestingly,post-shearmovementanddel

7、ayedfracturesaleobservedwithPTVafterastepstrainshearwhen】argeshearratesandstrainsareimposed．Withex-situSR-}tWAXD，wefoundthatthelayersmovingforwardkeephighcrystalorientatiomwhilethelayersmovingbackwardshowbworientations，whichmanifestsanon-uniformdistributionofcrystalorient