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采用不同粒径的Ni粉与硅橡胶(110型)按质量比2.4∶1.0制成Ni/硅橡胶复合材料,分别测量了其压敏导电性及介电性质,并结合扫描电镜照片对其微观导电机制进行了分析。结果表明随着填料Ni粉粒径的减小,Ni/硅橡胶复合材料的直流电阻率对外加压强更加敏感:在低压强下,粒径为74、48和18μm的样品的电阻率随压强的变化率分别为1.73×104、2.59×104和3.71×104Ω.m/kPa。样品直流电阻率陡降的区域随粒径的减小向压强较小的方向移动,显示出复合材料的渗流阈值与填充粒子的粒径有关:粒径越小,渗流阈值也越小。Ni/硅橡胶复合材料的交流电导率、介电常数、介电损耗均随填料Ni粉粒径的减小而变大:Ni粉粒径为18μm的Ni/硅橡胶复合材料的电导率约为10-2S.m-1,比74μm粒径样品的电导率(约10-7S.m-1)提高了5个数量级;对应的介电常数由约102提高到约103。改变填料Ni粉粒径可以有效地调节复合材料的弹性和压敏、电输运特性。
Ni / Silicone rubber composites with different particle sizes of Ni powder and silicone rubber (110 type) were prepared at the mass ratio of 2.4:1.0, and their pressure-sensitive conductivity and dielectric properties were measured respectively. The microscopic Conducting mechanism was analyzed. The results show that the DC resistivity of Ni / Silicone rubber composites is more sensitive to applied pressure as the particle size of filler Ni decreases: the resistivity of samples with particle sizes of 74, 48 and 18 μm at low pressure increases with the increase of pressure The rate of change was 1.73 × 104,2.59 × 104 and 3.71 × 104Ω.m / kPa. The region where the DC resistivity drops sharply decreases with the decrease of particle size, which indicates that the percolation threshold of the composite is related to the particle size of the filler particles. The smaller the particle size, the smaller the threshold of seepage. The AC conductivity, dielectric constant and dielectric loss of Ni / Silicone rubber composites increase with the decrease of particle size of Ni powder. The conductivity of Ni / Silicone rubber composites with Ni powder particle size of 18μm is about 10-2S.m-1, which is five orders of magnitude higher than that of the 74μm particle size sample (about 10-7S.m-1); the corresponding dielectric constant increases from about 102 to about 103. Changing the particle size of the filler Ni powder can effectively adjust the elastic and pressure-sensitive properties of the composite material.