CB/CNTs/PP导电高聚物力/温度作用下介电性能的研究

Research on dielectric properties of CB/CNTs/PP conductive polymers under force/temperature

以聚丙烯(PP)为基体,炭黑(CB)和碳纳米管(CNTs)为填料,通过熔融共混、注塑成型制备导电复合材料,测定电场频率、填料种类、填料含量以及温度、载荷等因素对其介电性能的影响。结果表明,室温下,随着填料含量的增加,材料介电常数和介电损耗均呈增大趋势;随着频率的增加(100 Hz^10MHz),介电常数和介电损耗首先迅速降低,然后逐渐趋于稳定;随着CNTs的加入,CB/CNTs/PP导电复合材料的介电常数明显增大,但是当填料含量达到某一定值时,继续增大CNTs的含量,介电常数反而下降;同一频率下,随着温度的升高(30~100℃),由热膨胀引起炭黑粒子间距的变化会导致介电常数减小。复合材料压缩实验表明:压缩载荷作用下,材料发生形变,基体中的CB粒子间相对位置改变,引起介电常数减小。

Conductive composites were prepared by melt blending and injection molding using polypropylene(PP) as a matrix and carbon black(CB) as fillers. The effects of electric field frequency, filler type, filler content, temperature and load on dielectric properties of the composites were determined. The results show that the dielectric constant and dielectric loss of the material increased with the increase of filler content at room temperature. With the increase of frequency(100 Hz-10 MHz), dielectric constant and dielectric loss of the composites decreased rapidly in the initial stage, and then tended to be stable. Dielectric constant of the composites increased significantly with the addition of CNTs, while when the filler content reached a certain value, the dielectric constant would decrease with the increase of CNTs. The change in space between carbon black particles caused by thermal expansion would decrease the dielectric constant of the composite with increasing temperature(30-100 ℃) at the same frequencies. The experimental results show that the material deformed with the compressive loading which would lead to the change of relative position between CB particles. As a result, the dielectric constant of the composites would decrease.