Dielectric Properties of Crosslinked Polypropylene by Gamma-ray Irradiation for Film Capacitor

In this paper, a cross-linked polypropylene (XLPP) preparation method by gamma $\boldsymbol{(\gamma)}-\mathbf{ray}$ irradiation was investigated to improve the dielectric properties of polypropylene (PP). With adding 0.2 wt% sensitizer trimethylolpropane triacrylate (TMPTA), PP films were irradiated at doses of 0, 2, 5 and 10 kGy. The cross-linking degree was characterized through the gel method, and dielectric properties were investigated at different temperatures. Experimental results showed that the breakdown strength of the XLPP films increased by 12.7% and the conductivity decreased significantly. The cross-linking of molecular chains enhanced the intermolecular forces and formed a stable three-dimensional mesh structure. Therefore, the destruction of PP molecular chain by high-energy electrons is inhibited, and dielectric properties at high temperature is improved. This paper provides a feasible idea for the cross-linking modification method of PP for film capacitors.