Atmospheric pressure plasma surface treatment to enhance interfacial insulation and water resistance of PP/SIR composite insulation

Layered polypropylene/silicon rubber (PP/SIR) composites have been widely used as reinforced insulation in electrical equipment. However, PP/SIR interface in composites is susceptible to electrical and moisture corrosion, severely affecting the stability of electrical equipment. In this study, an interface enhancement method for PP/SIR is developed based on atmospheric pressure plasma surface modification. Through controlling reaction conditions, Ar and Ar/hexamethyldisiloxane (HMDSO) plasma are established to provide reactive species such as Ar* and Si-containing fragments, which could etch or deposit SiO_3∼4 film on PP and SIR surfaces. The plasma treatment increases surface roughness and introduces polar oxygen-containing groups, while the film deposition fabricates hydrophobic surfaces, as well as shallows the surface trap to inhibit charge accumulation. The modified surfaces are configured in pairs to form PP/SIR interface for interface performance optimization. It is demonstrated that plasma etching promotes interface breakdown voltage of PP/SIR by 97.3 %, but the etched interface suffers from moisture invasion. By contrast, plasma film deposition blocks moisture penetration in PP/SIR interface, and synchronously contributes to the highest improvement of interface breakdown voltage (increased by 137.3 %). The facile plasma strategy could tailor multiple performances of surfaces and interfaces, which is of great significance for advanced dry-type modification in emerging applications.