PS-HI／EVA／CB复合材料导电性能的研究及结构分析

Studies on Conductive Behavior and Structure of PS-HI/EVA/CB Composite

采用XRD、DSC、SEM等研究了低熔点、半结晶聚合物EVA对非晶聚合物高抗冲聚苯乙烯／炭黑(PS-HI／ CB)复合材料的结构、导电性和正温度系数(PTC)效应的影响,结果表明,EVA,可提高复合材料的PTC强度,当PS- HI/EVA/CB=70:30:30时复合材料的PTC强度由不加EVA的2．2提高到5．1;复合材料的PTC转变温度与EVA 的熔点接近,因此,通过添加不同熔点的聚合物可实现控制复合材料的PTC转变温度的目的;SEM照片显示,随着 EVA含量的增加,两相结构发生变化,PS-HI由连续相转为椭圆形分散相,EVA由共连续结构转为网络状结构,直至网络状结构消失,而这种两相结构变化与复合材料的电阻率变化一致。

Influences of low melting point and semi-crystalline EVA on the structure, conductive behavior and positive temperature coefficient （PTC） of PS-HI/CB system were studied by means of XRD, DSC and SEM. It is showed that the addition of EVA improves the PTC strength. When PS-HI/EVA/ CB is 70：30：30, its PTC strength goes up to 5. l from 2.2, and its PTC transition temperature is close to that of EVA. Therefore, incorporation of polymers with different melting points can control the PTC transition temperature of the system. SEM photos show that the structure of the two phases changes with the increasing loadings of EVA, and simultaneously the continuous PS-HI phase transfers to oval distributive phase; the structure of EVA tends to be network and disappears at last. The phase structure transfer conforms to that of conductivity of the system.