Structure and Properties of Model Polybutadienes,

íosG.RubberMicrostructureonHIPSDynamicMechanicalPropertiesStructureandPropertiesofModelPolybutadienesandHIPS:Effectof:Publishedby:://jep.sagepub.com/cgi/alertsEmailAlerts::::©2006SAGEPublications.Allrightsreserved.Notforcommercialuseorunauthorizeddistribution.atPENNSYLVANIASTATEUNIVonFebruary8,2008*ANDRAFAELHERRERAN.DepartamentodeIngenierı´aQuı´micaLaboratoriodePolı´merosL-213,FacultaddeQuı´micaUniversidadNacionalAuto´nomadeMe´xicoC.P.04510,Me´xicoD.F.,Me´xicoLEONARDORI´OSG.InstitutoMexicanodelPetro´leoEjeCentralLa´zaroCa´rdenas152C.P.07730,Me´xicoD.F.,Me´xicoABSTRACT:Highimpactpolystyrene(HIPS)serieswassynthesizedbythemass-suspensionprocessusingpolybutadiene(PB)rubberswithdifferentcis-1,4,trans-1,4,andvinyl-1,2isomerscontent.TheHIPSwerecharacterizedbyTEM,GPC,DMA,andDSCanalyses.ItwasfoundthatthedynamicmechanicalpropertiesofHIPSstronglydependuponthemicrostructureofPBusedasamodifierduetothedifferenttendencyofPBisomerstopromotegrafting,cross-linking,andcrystallization.TheDMAforHIPSsynthesizedfromhighcisandhightransrubbersshowadditionalrelaxationsatthelowtemperatureregion.TheDSCresultsforgelsextractedfromtheseHIPSexhibitedmeltingendothermsconfirmingtheexistenceofcrystallinedomains.*Authortowhomcorrespondenceshouldbeaddressed.E-mail:[e-mail]DPLASTICSVol.38–April20061330095-2443/06/020133–14$10.00/0DOI:10.1177/0095244306057255
2006SAGEPublications©2006SAGEPublications.Allrightsreserved.Notforcommercialuseorunauthorizeddistribution.atPENNSYLVANIASTATEUNIVonFebruary8,2008(HIPS),studiesthathaveallowedlittle-by-little,theunderstandingofexistingrelationshipsbetweenthestructuresofpolybutadiene(PB)impactmodifiers,theirpropertiesand,alsothepropertiesofHIPScompositematerialsmadefromthem.However,thereareafewworksthattakeintoaccountPBmicro-structureeffect(microstructureunderstoodasmolepercentageofcis-1,4,trans-1,4,andvinyl-1,2unitspresentinPBpolymerchains)ontheirdynamicmechanicalproperties[1]andonthedynamicmechanicalpropertiesofmodifiedpolystyrenes.Existingworks[2–6]donotconsiderthedifferenttendencyofPBisomerstopromotegrafting,cross-linking,andcrystallizationinsiderubberparticlesandthewaytheyaffectdynamicmechanicalpropertiesofHIPS,butratherfocusonexaminingtheeffectofotherinterestingfactors,suchasoscillatingfrequency[2],degreeofgraft[3],particlescavitation[4],blockcopolymeraddition[5],andrubberphasevolumefraction[6].Aspriorworkslackthestudyofimpactmodifier’smicrostructureeffectonthemechanicalandthermalpropertiesofHIPS,andbecausetheresearchofPBmicrostructureeffectonHIPSpropertiesisofinterestforMexicanHIPSproducersauthorsdecidedtoperformsuchstudyinthepresentwork.EXPERIMENTALMaterialsStyrenemonomer(industrialgrade)wasobtainedfromPEMEX.Methylethylketone(MEK,industrialgrade)andtetrahydrofuran(THF,HPLCgrade)weresuppliedbyMallinkrodtBaker,Inc.Peroxidecompoundinitiators:1,1-di(tert-butylperoxy)-3,3,5-trimethyl-cyclohexane(T-29),1,1-di(tert-butylperoxy)cyclohexane(T-22E50),2,5-dimethyl-2,5-di(tert-butylperoxy)hexane(T-101),andEthapolTMsuspendingagent(acryliccopolymer)wereallprovidedbyAkzoNobel.AntioxidantIrganox1076,demoldingagent(derivedfromstearicacid),134M.R.RIVERAETAL.©2006SAGEPublications.Allrightsreserved.Notforcommercialuseorunauthorizeddistribution.atPENNSYLVANIASTATEUNIVonFebruary8,2008(plasticizer),potassiumhydroxide,(KOH,99%purity),andtoluene(industrialgrade)wereprovidedbyGIRSA.Allreagentswereusedasreceived.SynthesisAseriesofPBswithdifferentmicrostructuresweresynthesizedanionicallyandcharacterizedasreportedelsewhere[1].Tonamethem,abbreviationsaccordingtotheisomercontent(mole)areused:HCforhighcis(96%ofcis-1,4units);HTforhightrans(82%oftrans-1,4units);MCTformediumcisandtrans(42%ofeachcisandtrans),andLCTforlowcisandtrans(10%ofeachcisandtrans,but80%ofvinyl-1,2units).TheHIPSmaterials(identifiedbyaninitialHfollowedbythenameofPBemployedontheirsynthesis)wereallproducedbyamass-suspensionprocessinaCEMCOTM1gallonjacketedreactorfittedwithanrpmdetector,temperatureandpressuresensors,acombinedanchorandpropellerstirrer,anoilbathforheating,andappropriateconnectionsforkeepingN2(g)ine