茂金属聚乙烯改性低密度聚乙烯中空间电荷的机理研究

Study on Mechanism of Space Charge in Low Density Polyethylene Modified by Metallocene Catalyzed Polyethylene

针对高压,超高压直流塑料电缆中存在的空间电荷效应,文中选用与普通低密度聚乙烯(LDPE)化学结构相似的茂金属聚乙烯(MPE)作为成核剂与LDPE共混,用电声脉冲法(PEA)测量了共混物的空间电荷特性,以差示扫描量热法(DSC)研究了共混物的非等温结晶行为,用高阻计测量了共混物的体积电阻率的变化,结合聚合物的结晶和导电理论,讨论了共混物中空间电荷的形成和抑制机理。测试结果表明:1%的MPE与LDPE共混,能有效降低LDPE中空间电荷效应,提高结晶温度,降低体积电阻率。

Space charge effect is undesirable for HV and EHV plastic power cable. Metallocene catalyzed polyethylene （MPE）, used as a nucleator, is blended into 10w-density polyethylene（LDPE）. Then the space charge profile in the blends（MPE/LDPE） is measured by pulsed electro-acoustic （PEA） method, and at the same time the crystallization are Studied by differential scanning calorimerty （DSC） method. In addition, the volume resisitivity of MPE/LDPE is measured by micro-current detector. At last, based on the theories of crystallization and conduction of polymer, the formation and inhibition mechanisms of space charge in the blends are discussed. It is shown by the test results that LDPE blended with 1%wt MPE could effectively decrease the space charge effect, improve the temperature of crystallization, and reduce the volume resisitivity.