加工工艺对聚乙烯分子链取向调控及力学性能的影响  

Effect of Processing Technology on Molecular Chain Alignment of Polyethylene and Their Mechanical Performance

作　　者：何蓉[1] 周金彩[1] 毛文祺[1] He Rong;Zhou Jincai;Mao Wenqi(Hunan Institute of Science and Technology,Changsha 410118,China)

机构地区：[1]湖南科技职业学院,长沙410118

出　　处：《工程塑料应用》2018年第10期63-67,共5页Engineering Plastics Application

基　　金：2017年度湖南省自然科学基金项目(2017JJ5030);2016年度湖南科技职业学院院级课题项目(KJ16101);2016年度湖南省职业院校教育教学改革研究项目(ZJGB2016059)

摘　　要：研究了不同注塑加工条件下聚乙烯样条力学性能和分子链取向的情况,并对其分子链取向和力学性能的关系进行了分析和讨论。结果表明,在较高的料筒温度和剪切速率下,聚乙烯分子链段更容易发生取向;而在较低模具温度和较高的冷却速率下,聚乙烯分子链段不易发生解取向。提高料筒温度、剪切速率和冷却速率,同时降低模具温度,有利于保持聚乙烯样条中分子链段的取向态,从而使得相应聚乙烯样条的力学强度提高。为了研究加工工艺对不同链结构聚乙烯性能的影响,选用线型结构的聚乙烯5 000s和自制长链支化聚乙烯进行对比。当料筒温度、剪切速率、模具温度和冷却速率分别为180℃,300r/min,50℃,30℃/s时,聚乙烯5 000s样条的拉伸强度为25.2MPa,断裂伸长率为180%;长链支化聚乙烯样条的拉伸强度为21.3MPa,断裂伸长率为589%。The mechanical properties and polymeric chain orientation of polyethylene samples under different injection processing conditions were mainly investigated.The influences of polymeric chain orientation on the mechanical properties were analyzed and discussed.The results show that higher temperature and shear rate are in favor of the orientation of the polymeric chains of polyethylene,while lower die temperature and higher cooling rate show suppressed effects on the disorientation.It is beneficial to keep the orientation state of the molecular chain in the polyethylene sample and improve the mechanical strength of the polyethylene sample by increasing the temperature of the barrel,the shear rate and the cooling rate,as well as reducing the temperature of the die.Polyethylene 5 000 s and long chain branched polyethylene were used to investigate the effects of the processing parameters on the performances of polyethylene with various micro-structures.When the barrel temperature,shear rate,die temperature and cooling rate are 180℃,300 r/min,50℃and 30℃/s respectively,the tensile strength of the corresponding polyethylene 5000 s is 25.2 MPa,and the elongation at break is 180%,the tensile strength of the corresponding long chain branched polyethylene is 21.3 MPa,and the elongation at break is 589%.

关 键 词：聚乙烯 注塑加工 工艺优化 分子链取向 力学性能 

分 类 号：TQ325.1[化学工程—合成树脂塑料工业]