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1、PolymerDegradationandStability95(2010)593e599ContentslistsavailableatScienceDirectPolymerDegradationandStabilityjournalhomepage:www.elsevier.com/locate/polydegstabAdielectricstudyofmolecularrelaxationsinirradiatedhighdensitypolyethyleneG.Stamboliev,E.Su
2、ljovrujic*InstituteofNuclearSciences“Vinca”,P.O.Box522,11001Belgrade,SerbiaarticleinfoabstractArticlehistory:Themolecularrelaxationbehaviourofhighdensitypolyethylene(HDPE),exposedtogammaradiationinReceived14October2009airtovariousabsorbeddoses(upto700kG
3、y),hasbeeninvestigatedbydielectricloss(tand)analysis.AllReceivedinrevisedformrelaxationzones(g,banda,inorderofincreasingtemperature),between25Kandthemelttemper-27November2009ature,werestudiedinthefrequencyrangefrom1kHzto1MHz.Thechangesobservedinthediele
4、ctricAccepted14December2009relaxationspectrawererelatedtothemodificationsinthestructuralandmorphologicalparametersAvailableonline23December2009attributedtoexposureofthesamplestoradiation.Radiation-inducedchangesinthecrystalfraction,oxidativedegradationan
5、ddegreeofnetworkformation,observedbywideangleX-rayscatteringKeywords:(WAXS),differentialscanningcalorimetry(DSC),infraredspectroscopy(IR)andgelmeasurements,wereHDPEIrradiationwellconnectedwiththechangesinintensity,positionandactivationenergyofaandgrelax
6、ations.DielectricrelaxationsCompletedisappearanceofthealreadyweakbrelaxationwithirradiationisattributedtothemoreCross-linkingrestrictedchainsegmentmobilityinthenetstructure,butthecontributionduetoradiation-inducedOxidativedegradationincreaseincrystallin
7、ityshouldalsobetakenintoaccount.Ó2009ElsevierLtd.Allrightsreserved.1.Introductionthattheaprocessisdielectricallyactiveduetoreorientationofcarbonylgroupsinthechainsinthecrystallinephase[7].BoydIndielectricandmechanicalrelaxationstudies,polyethyleneandMan
8、sfieldhaveproposedthatthedielectricaprocesscanbe(PE)displaysthreecharacteristicrelaxationszones;thesehaverepresentedbypropagationprocessofatwisteddefectalongtheconventionallybeendesignatedasa,b,andgrelaxationinorderchainwithinacry
