聚乙烯基炭黑复合PTC材料的研究

STUDY ON PTC MATERIALS MADE BY POLYETHYLENE AND CARBON BLACK COMPOSITES

研究了以两种不同的高密度聚乙烯为基体炭黑复合材料的电阻正温度系数 (PTC)特性与填料浓度、加工工艺及后处理条件的关系 ,给出了最优化工艺条件。实验结果表明 ,两种聚乙烯 /炭黑复合材料在材料的混炼和后处理工艺、以及室温电阻R0 和PTC特性等方面都表现出较大的差异。具有高熔融指数的聚乙烯 /炭黑复合体系 (PE2 0 /CB)具有良好的易混炼性和材料的均匀性 ,并且当炭黑含量在 18%— 2 6 %范围内变化时 ,材料具有较理想的R0 和PTC性能。低熔融指数聚乙烯 /炭黑复合体系 (PE2 /CB)则在材料的稳定性和NTC现象的消除方面胜出一筹。

The influences of processing conditions on polyethylene/carbon black composites with two types of PE are studies in this paper, including mixing temperature, mixing time, additives, heating treatment and irradiation. And the optimized process conditions are obtained. It is found that the composites based on different PE matrices exhibit different properties, which is attributed to the different viscosity of the matrices. PE20/CB composites show excellent mixing properties, low room-temperature resistivity and considerable PTC effect when containing 18%-26% content of CB, while PE2/CB composites are much better in stability and the elimination of NTC effect. It is suggested that the combination of different matrices in one composite may be a convenient method to fabricate more superior polymeric PTC materials.