基于共凝聚PTFE/炭黑粒子复合材料的制备和性能

Preparation and Properties of Composites of Carbon Black Reinforced Polytetrafluoroethylene Prepared by a Two-step Process

在不使用凝聚剂的情况下采用下压式机械搅拌方式使聚四氟乙烯(PTFE)乳液和炭黑(CB)共凝聚,得到颗粒大小均匀的PTFE/CB粒子,然后用冷压成型和高温烧结工艺制备PTFE/CB复合材料,研究了烧结温度和CB含量对PTFE/CB复合材料的力学性能、导电性能和结晶度的影响。结果表明,烧结温度为390oC时复合材料中形成了均匀分布的微纤结构,力学性能最好;CB的填充明显提高了PTFE的力学性能和导电性能,当CB含量(质量分数)为2%时复合材料的力学性能最佳,拉伸强度从19.1 MPa增加至27.3 MPa,断裂伸长率从420%增加到525%。CB含量提高到3%的PTFE/CB复合材料结晶度最大,且CB在PTFE基体中形成了导电网络,电导率出现"逾渗",PTFE/CB复合材料具有抗静电性能。

Uniform complex particles of polytetrafluoroethylene（PTFE）/carbon black（CB） were firstly hetero-coagulated without additives of non-ionic surfactant by mechanical stirring. Then composites of PTFE/CB with better properties were successfully prepared via cold pressing and sintering method with complex particles of PTFE/CB as raw material. The effect of sintering temperature and the CB amount on properties of composites PTFE/CB was investigated. Results show that the optimum sintering temperature was 390 oC, and the mechanical properties of composite PTFE/CB sintered at 390 oC exhibited significantly better mechanical properties due to the formation of good micro-fibrous structure. Among others,with the CB addition of 2 mass%, the composite exhibited the best mechanical properties, i.e. its tensile strength increased from 19.1 MPa to 27.3 MPa and the elongation at break increased from 420% to525%. Importantly, the electrical conductivity could reach the percolation threshold for the composite with3 mass % CB due to the formation of a conductive network in the PTFE/CB matrix. Therefore, it follows that the composite of PTFE with 3 mass % CB can possess high degree of crystallinity with appropriate antistatic performance.