摘要
研究了高密度聚乙烯 /石墨导电复合物的PTC行为及其影响因素 ,揭示了内应力随温度升高而松弛对PTC效应的贡献。复合物的导电性能与PTC行为是由导电网络的总体结构及其随温度的变化所决定的 ,与材料组分性质以及各组分之间的相互作用关系不大。当环境温度趋于基体熔点时 ,复合物热学性质的变化造成导电网络的大规模破坏 ,是PTC行为产生的根源。热处理等物理手段可改变导电网络的微观结构 ,但不影响PTC行为赖以产生的物理机制 ,也不能有效改善PTC行为的热循环稳定性。
The PTC behavior and its stability of high-density polyethylene/graphite (HDPE/GP) composites were studied. The results show that the internal stress is one of the factors which result in the PTC transition and influence the PTC behavior. The conduction as well as the PTC behavior of conductive polymer composites is determined by the overall structures of the conducting network and its structure changes at ambient temperature, but it is independent of the filler contents and the interfacial interaction between the filler and the matrix. The changes in thermodynamic properties lead to the damage of the conducting network when the ambient temperature approaches to the melting point of matrix, which might be the essential reason for PTC behavior. Some physical means, such as thermal annealing, can produce arbitrary changes in the microstructure of the network. However, the physical mechanisms which cause the PTC behavior can not be changed at all. Furthermore, the PTC stability in thermal cycles can not be improved remarkably by such means.
出处
《功能高分子学报》
CAS
CSCD
2001年第1期39-44,共6页
Journal of Functional Polymers
基金
国家自然科学基金!资助课题 ( 5 0 0 0 3 0 0 7)
国家高技术新材料专家委员会重点资助!课题 ( 715 0 0 70 0 80 )
