Effect of spherical copper particle size on the negative permittivity behavior of copper/polypropane composite

In this work, the conductive composites were manufactured by hot pressing with polypropylene (PP) as matrix resin and copper powder as conductive filler. The effects of copper particle radius and content on the dielectric properties of the composites were studied. The results show that dielectric constant of the composite was greatly improved than that of pure PP material. With the increase of copper content, the conductive percolating network was established within the composites. Along with the percolation phenomenon of microstructure, the conductive mechanism simultaneously changed. The absolute value of the negative permittivity also increases to 2.2 x 10(6). Moreover, the negative permittivity was observed by tuning their compositions and tailoring their microstructures. Further investigation revealed that there was a constitutive relationship between permittivity and reactance.