Ni/硅橡胶复合材料的压敏与介电特性

Pressure sensitivity and dielectric properties of Ni/silicone rubber composite

采用硅橡胶(110型)与金属(Ni粉)按质量比1∶2配料,经过特殊的制备工艺,合成金属Ni/硅橡胶高分子复合材料。分别测量样品的压敏效应和介电特性。结果表明:在不同应力作用下,样品的电阻从1×1012Ω降到10Ω,其变化范围为11个数量级;在恒应力作用下,样品的电阻随时间的增加而减小,表现出"电阻蠕动"现象;室温下,样品的电容和介电损耗都随频率的增加而减小,随应力的增加而增大,其原因是在样品中形成了以高分子为绝缘层、金属Ni粉为导电填料的相互隔离且平行的超电容网络微观结构。在外力作用下,这种微观结构中每一个电容单元的间距逐渐减小而电容逐渐增大,致使样品的电容有大幅度增加;介电损耗是由于样品的电阻率减小,电导增大,使部分电能转化为热能。

Nickel - silicone rubber polymer composites were prepared using silicone rubber and nickel powder at a ratio of 1 ： 2. The effect of pressure and the dielectric properties of the composite samples at room temperature were measured. The results show that the resistance of samples under modest compression can fall from about 1 × 10^12Ω to〈10Ω, a change of 11 orders of magnitude. A resistance creep has also been observed： the resistance of samples under constant stress decreases with time. The permittivity and dielectric loss of the composite at room temperature decrease with increasing frequency but increase with application of uniaxial stress. This is because the special microstructure of a capacitor network formed by the metallic filler particles and the insulating polymer materials of the composite. Under uniaxial pressure, the distance between metallic particles decreases, leading to an increase in capacitance and conductivity, which in turn results in an increase in dielectric loss.