文档名：低密度聚乙烯基料链结构对黏弹特性的影响
摘要：高压电缆向高电压等级和大长度的发展,对交联聚乙烯绝缘料的加工性能提出了更高的要求.绝缘料的加工性能和电缆绝缘成型质量主要受低密度聚乙烯(LDPE)基料黏弹特性影响,基料的黏弹特性取决于其链结构.然而,由于LDPE基料分子链支化结构复杂,难以建立单一的链结构参数与黏弹特性的关联,因此精准地获得LDPE链结构特征对黏弹特性的影响对电缆绝缘优化升级至关重要.该文采用制备型升温淋洗分级工艺,对管式法LDPE和釜式法LDPE进行分级得到具有不同平均分子量的级份,采用凝胶渗透色谱法和旋转流变仪表征原料和级份的链结构参数及黏弹特性.结果表明,长链支化结构相似时,重均分子量越大,分子链间越容易产生缠结,黏度和模量越高,剪切变稀现象发生频率越低;重均分子量接近时,零切黏度与长链支化度具有非单调关系,过高的长链支化度会削弱分子链间的物理缠结,导致零切黏度降低.基于LDPE黏弹特性构效关系,结合电缆挤出成型工艺,设计更为适宜的基料黏弹特性参数,以此优化调控LDPE的链结构,是未来高端电缆绝缘材料研发的方向.
Abstract：Ashighvoltagecabletransmissionsystemsdeveloptohighervoltagelevelsandlongerdistances,thethicknessandlengthofcableinsulationlayersareincreasing,whichplaceshigherdemandsontheprocessingpropertiesofcrosslinkedpolyethyleneinsulatingmaterials.Theviscoelasticityoflow-densitypolyethylene(LDPE)directlyaffectstheprocessingperformanceoftheinsulatingmaterialsandultimatelydeterminethemoldingqualityofcableinsulation.WhilethemolecularstructureofLDPEisthekeytodetermineitsviscoelasticity.However,duetothecomplexbranchingarchitecturesandbroadlydistributedchainstructureofLDPE,itischallengingtoestablishtherelationshipbetweenasinglemolecularchainstructuralparameterandviscoelasticity.Therefore,accurateobtainmentoftheinfluenceofLDPEmolecularchainstructuralcharacteristicsontheviscoelasticityissignificantforcableinsulationoptimizationandupgrading.Inthispaper,preparativetemperature-risingelutionfractionation(P-TREF)wascarriedouttoseparateatubularLDPEandanautoclaveLDPEintofractionswithdifferentaveragemolecularweight.ForeachLDPEsample,twofractionswithhighcontentandlargemolecularweightdifferenceswereselectedforsubsequentexperiments.MolecularstructuresoftheoriginalLDPEsamplesandtheirfractionswerecharacterizedbygelpermeationchromatographyandtheirviscoelasticparameterssuchascomplexviscosity,storagemodulusandlossmodulus,weremeasuredusinganelectromagneticrheometer.TheresultsshowthattheLDPEresinspreparedbydifferentprocessexhibitsignificantlydifferentmolecularchainstructurecharacteristics.TheshapeofmolecularweightdistributionfortheautoclaveLDPEisbimodal,withmoremoleculesofhighermolecularweightandawidermolecularweightdistribution.Ithashigherlong-chainbranchingdegreeanditsmolecularchainarchitectureisclosertoasphere.Itisclosertostarbranchedpolymer.WhilethetubularLDPEfeaturesaunimodalmolecularweightdistributioncurvewithasmalleraveragemolecularweightandanarrowermolecularweightdistribution.Ithasfewerlongchainbranchingpermoleculeanditsmolecularchainarchitectureisclosertoarod.Atthesameweightaveragemolecularweight,thezero-shearviscosityofautoclaveLDPEiscomparativelylowerthanthatoftubularLDPE.ForthetwoLDPEresins,therelationshipbetweenzero-shearviscosityandweightaveragemolecularweightisasfollows:fortheautoclaveLDPE,η0∝Mw3.4,whileforthetubularLDPE,η0∝Mw6.7.Theresearchinthispaperalsofoundthatwhenthelongchainbranchingtopologyissimilar,thelargertheweightaveragemolecularweight,themoreprobabletocreateentanglementbetweenmolecularchains.Thus,theviscosityandmoduliarehigherandtheshearthinningphenomenonappearsatlowerfrequency.Whentheweightaveragemolecularweightisclose,thezero-shearviscosityhasanon-monotonicrelationshipwiththedegreeoflong-chainbranching.Excessivelong-chainbrancheswillweakenthephysicalentanglementbetweenmolecularchains,resultinginadecreaseinthezero-shearviscosity.Basedonthestructure-activityrelationshipofviscoelasticityofLDPE,andcombineditwithcableextrusionmoldingprocess,itisfeasibletodesignmoresuitableviscoelasticityparametersofLDPEinsulatingmaterials,andoptimizethechainstructureofLDPEaccordingtothis.Thisisthefuturedirectionoftheresearchanddevelopmentofadvancedcableinsulatingmaterials.
作者：吴一帆 王诗航 李盛涛 摆音娜 景政红 徐治 楼铁城 Author：WuYifan WangShihang LiShengtao BaiYinna JingZhenghong XuZhi LouTiecheng
作者单位：电工材料电气绝缘全国重点实验室(西安交通大学)西安710049中国石化北京燕山分公司北京102500国网上海市电力公司电缆分公司上海200072
刊名：电工技术学报
Journal：TransactionsofChinaElectrotechnicalSociety
年，卷(期)：2024, 39(1)
分类号：TM215
关键词：高压电缆 低密度聚乙烯 黏弹特性 分子链结构
Keywords：Highvoltagecable low-densitypolyethylene viscoelasticity molecularchainstructure
机标分类号：TQ325.12O634.4+1TM215
在线出版日期：2024年1月18日
基金项目：国家电网有限公司总部科技项目，国家自然科学基金低密度聚乙烯基料链结构对黏弹特性的影响[
期刊论文] 电工技术学报--2024, 39(1)吴一帆 王诗航 李盛涛 摆音娜 景政红 徐治 楼铁城高压电缆向高电压等级和大长度的发展,对交联聚乙烯绝缘料的加工性能提出了更高的要求.绝缘料的加工性能和电缆绝缘成型质量主要受低密度聚乙烯(LDPE)基料黏弹特性影响,基料的黏弹特性取决于其链结构.然而,由于LDPE基料...参考文献和引证文献
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