稀土改性剂对玻璃纤维-SiO2/聚四氟乙烯复合材料性能的影响

采用不同的稀土改性剂（La、Ce、Pr、Nd和Sm）对SiO₂和玻璃纤维（GF）进行改性处理，SiO₂含量为55wt%，GF含量为2wt%。填料改性处理后与聚四氟乙烯（PTFE）分散液在高速分散机中混合，然后通过热压烧结法制得GF-SiO₂/PTFE复合材料。考察了不同的稀土改性剂对GF-SiO₂/PTFE复合材料吸水性、介电性能、热膨胀系数和力学性能的影响。采用FTIR手段对稀土La改性剂，未改性的填料和改性后的填料结构进行了测试。并用SEM和EDS对复合材料的断口形貌及表面处理前后填料的形貌进行观察和能谱分析。结果表明：由于稀土La的电子层结构比其他轻稀土更稳定，对阴离子的吸引作用比其他轻稀土强，稀土La改性剂比其他的稀土改性剂能更好地促进填料GF与PTFE界面粘合，改善GF-SiO₂/PTFE复合材料性能。GF-SiO₂/PTFE复合材料的介电性能受到La含量的影响，当La含量为0.3wt%时介电性能最佳。

Effect of rare earth modifier on properties of glass fiber-SiO2/polytetrafluoroethylene composites

The different solution of rare earth modifier (La, Ce, Pr, Nd and Sm) were used to modify glass fiber (GF) and silica (SiO₂), the glass fiber-SiO₂/polytetrafluoroethylene (GF-SiO₂/PTFE) composites of 55wt% SiO₂ and 2wt% GF were mixed by a high-speed dispersion machine and prepared by hot-pressing. The effects of rare earth modifier on the properties of the composites material were investigated, such as the water absorption, the thermal, the dielectric properties, the tensile strength and morphology. The FTIR method was used to investigate the structures of rare earth La, unmodified filler and modified filler. The surface morphology and element were analyzed by SEM and EDS. The results show that rare earth La is superior to other rare earth modifier in promoting the interfacial adhesion between glass fiber and polytetrafluoroethylene (PTFE) and improving the water absorption, the coefficient of thermal expansion, the dielectric properties and tensile properties of the GF-SiO₂/PTFE composites due to the stable electronic structure of rare earth La and the strong attraction to the anion.. The dielectric properties of the GF-SiO₂/PTFE composites is mainly affected by the content of rare earth La, and the optimum performance of the GF-SiO₂/PTFE composites is obtained at 0.3wt% rare earth La content.