Effect of Crosslinking Agent Content on Dielectric Properties of PP Films Modified by EB Irradiation for HVDC Capacitor

The decline in breakdown strength and the rise in dielectric loss of polypropylene (PP) film at high temperatures are the key factors restricting the application of metalized film capacitors (MFCs). This article proposed a modification method using electron-beam (EB) irradiation to improve the high-temperature insulation performance of PP film for capacitors. The influence of crosslinking agent contents on the dielectric properties of irradiated crosslinked PP is investigated. The results show that the conductivity of EB-irradiated films doped with 0–2 wt% pentaerythritol triacrylate (PETA) is reduced by 26.9%–60.8% and the breakdown strength is enhanced by 2.8%–21.2% at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$125~^{\circ }$ </tex-math></inline-formula>C, resulting in better dielectric properties compared to pure PP films. The formation of a 3-D network structure by crosslinking can inhibit the thermal motion of molecular chains and improve their thermal stability, consequently limiting the transport behavior of carriers. Irradiation crosslinking modification can improve the high-temperature dielectric properties of PP films. This research provides a valuable reference for the crosslinking modification of PP films serving in MFCs.