Preparation And Properties Of Nano-ZnO/Silicon Rubber Composites

In electric industry, improved performance of high reliability and long life for micro-electronic devices is demanded due to the widely use of large scale integrated circuit. With outstanding electrically insulating and thermally conductivity, the electrically insulating and thermally conductivity polymer composite is playing an important role. On the basis of surveying of the relative literature about the electrically insulating and thermally conductivity polymer composite, three kinds of composites were prepared, using bi-component RTV silicon rubber as matrix, nanometer zinc oxide powder as filler which was treated by various modifying method and couple-used with zinc oxide whisker (ZnOw). The effects of fillers’ content, processing technology, modifying methods on the thermal conductivity, volume resistivity, dielectric property, thermal stability,mechanical properties, structure and other properties of compsite were deeply researched by modern analytical methods, such as thermal conductive tester, high insulation resistance meters, scanning electron microscopy. Through experiments, following conclusions can be obtained:With addtion of nano-ZnO filler, thermal conductivity of the composite can get an obvious improvement. When the fill amount of nano-ZnO was90phr, the thermal conductivity of composite came up to0.94W/(m-K), being more than3.7times of that of pure silicon rubber. The addition of nano-ZnO filler into silicon rubber decreases its volume resistivity whereas increases its dielectric constant and dielectric loss, however, it remains good electrically insulating properties. Besides, the thermal stability of the composite was enhanced with the addition of nano-ZnO filler.With surface-modification by stearic acid, KH570, A-172respectively, the agglomeration of nano-Zno filler in silicon rubber matrix could be improved. The thermal conductivity of composite was also effect by modification. The biggest increase of thermal conductivity could be obtained by using A-172as modifying agent. When the fill amount of A-172modified nano-ZnO was30phr, the thermal conductivity of composite came up to0.47W/(m-K), being23%more than non-modified composite. Meanwhile, the A-172modification had slightly effect on the volume resistivity and maintained a good dielectric property of the composite.The use of hybrid ZnO wisker and A-172modified nano-ZnO particles provides composite with better thermal conductivity than the role-particle filler used.Comparing some typical equation with experimental data of filled thermal conductive composites, Agari.Y’s equation was adaptable for nano-ZnO/silicon rubber composite in this research.