【摘要】 针对PTC材料体系,提出了"PTC强度可提高空间"与"体系提高PTC强度的能力"两个概念,以低密度聚乙烯(LDPE)、高密度聚乙烯(HDPE)和乙烯-醋酸乙烯共聚物(EVA)作为基体,以导电炭黑作为填充导电粒子,制备了聚合物基复合型PTC材料,详细分析了炭黑含量、EVA含量对PTC材料性能的影响.研究表明,所提出的有关概念可用于分析材料的PTC效应机理及各种因素的影响,有助于进一步对聚合物基PTC热敏导电材料作用机制的理解及研究;炭黑含量影响材料电阻率和PTC强度,炭黑含量取在逾渗区电阻率偏小处可得到较高的PTC强度;EVA含量不同时材料电阻率和PTC强度都有先减小后稍增大的现象.更多还原

【Abstract】 Two new concepts of "maximum PTC analogy" and "systems’ PTC abilities" were introduced and the mechanism of PTC(Positive Temperature Coefficient) effect of conductive polymeric composites systems was investigated. Then PTC conductive polymeric composites were prepared using LDPE/HDPE and EVA or their composites as matrix materials and conducting carbon black(20～40 nm) as conducting fillers by meltprocessing mixers and extruders. The effect of carbon black contents and EVA on the properties of the systems were discussed in detail and the differences in the effect of LDPE and HDPE in the PTC systems were studied with the help of the concepts introduced. The results show that the two concepts are helpful to understand the mechanism of PTC effect and the effects of the factors.更多还原