复配偶联剂对SiO_2/聚四氟乙烯复合材料性能的影响

制备了不同组分配比的氨丙基三乙氧基硅烷(KH550)-苯基三甲氧基硅烷(Z6124)复配偶联剂(KH550-Z6124)改性SiO2/聚四氟乙烯(PTFE)复合材料,系统地研究了KH550-Z6124组分配比对复合材料介电性能、吸水率和导热性能的影响。采用Lichtenecker模型计算了SiO2/PTFE复合材料的介电常数和介电损耗理论值,并与实验值进行对比。结果表明:当KH550、Z6124的含量(以SiO2的质量为基准)分别为0.3wt%和1.7wt%时,KH550-Z6124改性SiO2/PTFE复合材料的介电损耗由Z6124改性SiO2/PTFE复合材料的1.7×10-3降低至1.0×10-3,吸水率由0.082 6wt%降低至0.020 3wt%,导热率提高66%;SEM形貌分析发现KH550-Z6124改性SiO2颗粒在PTFE基体中均匀分散,界面连接更紧密;KH550-Z6124改性SiO2/PTFE复合材料的介电常数和介电损耗实验值更接近其理论值。

Influences of compound coupling agent on properties of SiO2/polytetrafluoroethylene composites

Aminopropyltriethoxysilane (KH550)-phenyltrimethoxysilan (Z6124) compound coupling agents with different components mixing ratios modified SiO₂/polytetrafluoroethylene (PTFE) composites were prepared, and the effects of mixing ratios of KH550-Z6124 components on the dielectric properties, water absorption rate and heat conduction properties were investigated systematically. Lichtenecker model was adopted to calculate the theoretical values of dielectric constant and dielectric loss of SiO₂/PTFE composites, and the theoretical values were compared with the experimental values. The research results show that when the mass ratios of KH550 and Z6124 to SiO₂ are 0.3wt% and 1.7wt%, the dielectric loss of KH550-Z6124 modified SiO₂/PTFE composites reduces from 1.7×10^-3 (Z6124 modified SiO₂/PTFE composites) to 1.0×10^-3, the water absorption rate reduces from 0.082 6wt% to 0.020 3wt% and thermal conductivity increases by 66%. The SEM microstructure analysis show that KH550-Z6124 modified SiO₂ particles disperse uniformly in PTFE matrix, and the interface connection is stronger. The experimental values of dielectric constant and dielectric loss of KH550-Z6124 modified SiO₂/PTFE composites are more closer to the theoretical values.