炭黑填充聚甲基乙烯基硅氧烷硫化胶的阻温特性与电阻弛豫

研究了炭黑填充硅橡胶硫化胶的热循环以及热处理过程中的导电行为,发现在热循环中阻温关系曲线逐渐向低电阻方向移动,而在恒温下发生电阻弛豫现象;分析了硫化胶的导电机制,讨论了阻温关系发生移动的原因.

Resistivity-temperature Properties and Resistivity Relaxation of Carbon Black Filled Poly(methyl vinyl siloxane) Vulcanite

The conduction behavior of carbon black(CB) filled poly(methyl vinyl siloxane)(PMVS) vulcanites undergoing thermal cycles or subject to thermal treatment at given temperatures was investigated. The conduction behavior in PMVS/CB crosslinked composites at room temperature followed the prediction of the statistical percolation theory. The negative temperature coefficient(NTC) effect of resistivity corresponded to thermal activation conduction mechanism, while the positive temperature coefficient(PTC) effect was related to the breakdown of conductive network caused by volume expansion. The results revealed that the resistivity-temperature properties during the thermal cycles was gradually changed towards low-resistance, while the change of resistance with variation of time at given temperatures exhibited resistivity relaxation behavior. The conductive mechanisms and corresponding changes in the structure of PMVS/CB responsible for the resistivity-temperature behavior were discussed. At given temperatures, the tesistance relaxation was strengthened with decreasing CB weight fraction. On the other hand, it is strengthened with increasing ambient temperature at given CB fractions.