不同纳米填料填充聚偏氟乙烯基复合材料的介电松弛行为

Dielectric relaxation behavior of PVDF-based composites filled with different nanofillers

以绝缘性BaTiO3、半导性SiC和具有导电性的纳米石墨片(GNP)为填料,采用溶液法制备了聚偏氟乙烯(PVDF)基复合材料,着重研究了具有不同性质的填料对PVDF基复合材料介电行为的影响。结果表明:随着不同纳米填料用量的增加,PVDF基复合材料的介电常数都有增大的趋势,尤其是添加半导性SiC和导电性GNP对PVDF基复合材料介电性能改善的效果最明显,其影响程度可由ε′-ε″曲线获知;当SiC和GNP含量高于渗流阈值后,其高频松弛峰趋于平直;采用介电模量的形式可以很好地描述材料在频率依赖下的松弛行为,其松弛激活能随着填料用量的增大而降低,表明填料的加入促进了PVDF基复合材料的极化。

Polyvinylidene fluoride(PVDF)based composites filled with insulating BaTiO3,semiconductive SiC and conductive graphite nanoplatelet(GNP)were fabricated by simple solution mixing process.The effects of different nanofillers on the dielectric behavior of PVDF-based composites were mainly investigated.The results show that the dielectric constant of PVDF-based composites is found to increase with the increasing of all nanofiller contents,particularly for the composites with semiconductive SiC and conductive GNP fillers.The dielectric relaxation behavior of SiC/PVDF and GNP/PVDF composites can also be verified viaε′-ε″plot,where the relaxation peaks of PVDFbased composites at high frequency region tend to be straight when the content of SiC and GNP reaches the percolation threshold.In addition,the form of dielectric modulus can well describe the relaxation behavior of the PVDFbased composites.The relaxation activation energy reduces with the increasing of nanofiller content,which indicates that the addition of the nanofiller improves the polarization of PVDF-based composites.