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1、FREERADICALDEGRADATIONOFPOLYPROPYLENEINTHEBULK:COUPLINGOFKINETICANDRHEOLOGICALMODELSPascaleAulagner,AuderAinser,ChristianCarrotandJacquesGuilletLaboratoiredeRheologiedesMatieresPlastiques,FacultedeSciencesetTechniques,VniversiteJeanMonnet,23,RueduDocteurPaulMichelon,42023Saint-Etienne
2、Cedex2,FranceABSTRACTFreeradicaldegradationofpolypropyleneinthebulkduringreactiveextrusionhasreceivedalotofinterestasanalternativemethodtoproduceresinswithawidevarietyofmolecularweightdistributions.Accuratedesignoftheresultingproducts,however,requiresabettercontroloftheprocess,whichca
3、nbeachievedbytheuseofconsistentmodelingoftheextrusionprocess.Forthispurpose,areasonableconstitutiveequationdescribingtherheologicalbehaviorofthematerialduringthereactiveextrusionoperationisnecessary.Thispaperinvestigatesthereliabilityofthecombinationoftwomodelsdescribingbothchemicalan
4、drheologicalaspectsoftheprocess.Thefirstmodeldescribesinasimplifiedmannerthekineticsofthefreeradicaldegradationandhelpstotakeintoaccountthecontinuouschangeofthemolecularweightdistribution(MWD)ofthepolymeralongthereactiontime.Ontheotherhand,variousmodels,fromempiricismtomoreelaborateon
5、esusingmoleculardynamics,willbepresentedtorelatetheMWDtotherheologicalbehavior.Theiruse,incombinationwiththepreviousmodeldescribingthekineticsofthedegradation,willbeshowntogiveaveryaccuratedepictionoftherheokineticaspectsofthefreeradicaldegradationofpolypropyleneresinsinaninternalmixe
6、rusingaperoxideasaninitiator.381Broughttoyouby
7、NewYorkUniversityBobstLibraryTechnicalServicesAuthenticatedDownloadDate
8、1/23/155:39AMVol.20,No.5,2000FreeRadicalDegradationofPolypropyleneintheBulk:KineticandRheologicalModelsKEYWORDSpolypropylene,freeradicaldegradation,meltrheology,kinet
9、icsINTRODUCTIONPolypropylenehasreceivedgrowinginterestinthelast20yearsbecauseofitspotentiallywidespectrumofusesandbecauseofitsgoodprocessability.Thehighversatilityofthispolymermaterialhasgainedafurtherincreasewiththeuseoffreeradicaldegradationinthebulkduringreactiveextrusion.Startingf
10、romal