Dielectric Performance of Furan-Functionalized Polypropylene Film for HVdc Capacitors

In this article, a modification method based on long-chain branching is proposed to improve the dielectric properties of polypropylene (PP) at high temperature. Long-chain branches are successfully grafted to linear PP using functional group reactions with furfuryl sulfide (FS). When FS is added at the amount of 0.05 wt%, the breakdown strength of the modified film is increased by 17.45% and the leakage conductivity is decreased by 86% at 125 °C. The energy storage density of the modified film is increased by 30.93% (25 °C) and 46.74% (125 °C). Functional monomers can form deep traps to capture electrons, and the long-chain branched structure can enhance the thermal stability of the molecular chain. The carrier concentration inside PP at high temperatures is efficiently reduced by the synergistic effect of functional monomers and long-chain branched structure.