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1、Macromolecules2006,39,8389-83988389ModelingofFlow-InducedCrystallizationofParticle-FilledPolymersWookRyolHwang,²GerritW.M.Peters,³MartienA.Hulsen,³andHanE.H.Meijer*,³SchoolofMechanicalandAerospaceEngineering,ResearchCenterforAircraftPartsTechnology(ReCAP
2、T),GyeongsangNationalUniVersity,Jinju,660-701,SouthKorea,andMaterialsTechnology,EindhoVenUniVersityofTechnology,P.O.Box513,5600MB,EindhoVen,TheNetherlandsReceiVedMay30,2006;ReVisedManuscriptReceiVedSeptember25,2006ABSTRACT:Wepresentastudyonflow-inducedcr
3、ystallizationofpolymersfilledwithrigidparticles.Thenumericalsimulationsrevealtheinterplaybetweenfillerparticles,thepolymermelt,flow,andflow-inducedcrystallization.Bothcrystallizationkineticsandtheresultingcrystalorientationareaffected,andtheyarecrucialfo
4、rthematerialpropertiesthatarecreatedduringflow.Intheanalysisoftheproblem,firstadirect2Dnumericalsimulationtechniqueforviscoelasticparticlesuspensionsisappliedtodeterminethelocalmolecularconformationduringtheflow.Subsequently,weusethisconformationasthedri
5、vingforceforflow-inducedcrystallization.Localanisotropiccrystallinestructuresareformedduetohighmolecularorientation,especiallyneartheparticles.Becauseofthepresenceofthesameparticles,regionsofthemeltareshieldedfromtheflow,andtherefore,hardlyanyeffectofthe
6、flowisseenintheseregions.Bothcoupledanddecoupledsimulationswereperformed.InthelastapproximationtheflowproblemissolvedusingageneralizedNewtonianviscousfluidmodel,andthevelocitygradientsobtainedarepluggedintoaviscoelasticconstitutivemodelthatprovidesthemol
7、ecularconformation.Itisfoundthatthedecoupledmethodgivesincorrectresults,especiallywithrespecttothemolecularandcrystallinestructureorientation.I.IntroductionrectangulartestbarthatonlyproducestestsamplesinflowThepioneeringworkoftheDuPont-MITgroup(Argonandd
8、irection,alsothedirectionperpendiculartoflowcouldbeCohenfromMIT)ontoughnessimprovementofdifferenttested.10Asexpectedinaccordancewiththecompressiontestsemicrystallinepolymersusinghardfillersratherthansoftsamples,notoughness