聚偏氟乙烯基复合材料的制备及介电性能

Dielectric properties and preparation of microcapacitor of polyvinylidene fluoride matrix composite

为有效改善聚合物基复合材料的介电性能,兼顾高介电常数和低填料量同时并存,采用以聚偏氟乙烯(PVDF)为基体树脂,钛酸钡(BT)和石墨烯(GNP)分别为介电填料和导电填料,在BT-GNP/PVDF复合体系内部构建微电容器结构。采用溶液法和热压法制备GNP/PVDF薄膜和BT-GNP/PVDF复合薄膜。结果表明,BT和GNP填料在BT-GNP/PVDF复合薄膜中能够均匀分散,在薄膜内能形成明显的微电容器结构。陶瓷填料BT的引入,使微电容器结构更有利于提高BT-GNP/PVDF复合薄膜的介电常数。BT含量大于50wt%的BT-GNP/PVDF复合薄膜介电常数均不低于GNP/PVDF薄膜。BT含量为50wt%的BT-GNP/PVDF复合薄膜的介电常数高于BT含量分别为35wt%、60wt%和70wt%的BT-GNP/PVDF复合薄膜,最大值约为43,相当于GNP含量为0.8wt%的GNP/PVDF薄膜的1.5倍;BT含量为50wt%的BT-GNP/PVDF复合薄膜损耗角正切均小于其他体系薄膜,最大不超过0.09,最小约为0.02。BT-GNP/PVDF复合薄膜的电导率变化趋势基本一致,没有明显差异。

In order to effectively improve the dielectric properties of polymer matrix composites and consider the coexistence of high dielectric constant and low filler content, the microcapacitor structure was constructed in the barium titanate-graphene/polyvinylidene fluoride(BT-GNP/PVDF) composite system with PVDF as the matrix resin, BT and GNP as the dielectric filler and conductive filler respectively. The GNP/PVDF films and BT-GNP/PVDF composite films were prepared by solution method and hot pressing method. The results show that the BT and GNP fillers can be evenly distributed in both the BT-GNP/PVDF composite films and they are easier to form microcapacitor structure in the hot-pressing films. With the introduction of BT, the structure of the microcapacitor formed between GNP and BT is more conducive to the improvement of the dielectric constant of the BT-GNP/PVDF composite films. The dielectric constant of BT-GNP/PVDF composite films with BT content more than 50 wt% are not lower than that of GNP/PVDF composites. The dielectric constant of BT-GNP/PVDF composite film with BT content of 50 wt% is higher than that of the BT-GNP/PVDF composite films with BT content of 35 wt%, 60 wt% and 70 wt%,respectively, the maximum is about 43, equivalent to 1.5 times of GNP/PVDF film with GNP content of 0.8 wt%. The dielectric loss of BT-GNP/PVDF composite film with BT content of 50 wt% is also smaller than other systems, the maximum value is no more than 0.09 and the minimum value is about 0.02. The conductivity of BT-GNP/PVDF composite films are in consistant change trend and there is no significant difference between them.