Abstract:

Using silver nitrate（AgNO₃）as raw material and polyvinylpyrrolidone（PVP）as protective agent，nano-silver with average size of 80 nm，100 nm，120 nm was prepared by UV chemical reaction in N,N-dimethylformamide（DMF）solution. Scanning electron microscopy and laser particle size analyzer were used to investigate the degree of dispersion and particle size of nano-silver. Nano Ag/epoxy composite was prepared by solution-ultrasonic method and was characterized with XRD，FT-IR spectroscopy. The effects of nanoparticle size and content of Ag on the electrical properties of composite were discussed. A specific size and distribution of nano-silver could increase the breakdown strength of the epoxy. The smaller the particle size of nano-Ag was，the more obvious enhancement of breakdown strength was observed. The dielectric strength of epoxy increased with increasing Ag content at first，and then decreased. Dielectric constant and dielectric loss of the composite had little change. It was assumed that the silver did not increase the system dielectric loss. These particular phenomena could be explained by “Coulomb blockade effect”. A theoretical and experimental basis for the dielectric properties of modified epoxy resin was provided.

摘要：

以硝酸银为原料，用聚乙烯吡咯烷酮（PVP）作保护剂，在N,N-二甲基甲酰胺（DMF）溶液中，通过光化学反应法分别合成了平均粒径为80 nm、100 nm、120 nm的银胶，并用扫描电子显微镜及激光粒度仪测试了其分散程度和粒径正态分布；采用溶液-超声法制备了纳米Ag/环氧树脂复合材料；采用XRD、FTIR表征了纳米Ag对环氧树脂的改性结果，并详细讨论了纳米Ag粒径及含量对复合材料介电性能的影响。结果表明：一定尺寸和分布的纳米金属粒子能够提高聚合物的击穿强度，纳米Ag的粒径越小，击穿强度的提升越明显；并且在固定粒径时，聚合物的击穿强度随着Ag的含量提高出现先增加又降低的趋势，介电常数和介电损耗却出现了先降低后增加的趋势，这种特殊的现象可以用库伦阻塞效应限制电荷运动的理论来解释。