Core-shell SiC/SiO₂ whisker reinforced polymer composite with high dielectric permittivity and low dielectric loss

A polymer composite with high dielectric permittivity and low dielectric loss was successfully fabricated by embedding core-shell structure whisker in polymer matrix. The novel core-shell structure of silicon carbide/silicon dioxide whisker (SiC/SiO₂-W) filler was prepared via a one-step air-exposure calcination treatment of original SiC whisker (SiC-W). The effects of semiconductor-insulator core-shell filler on morphology structure, mechanical properties, dielectric and electrical properties of poly(vinylidene fluoride) (PVDF) composite were investigated. Compared with SiC-W/PVDF composite, SiC/SiO₂-W/PVDF composite shows stronger mechanical properties, and dramatically suppressed dielectric loss and conductivity while remains high dielectric permittivity. Furthermore, the dielectric and electrical properties of the composite can be further optimized by adjusting the shell thickness. Especially, the composite with SiO₂ thickness of 6-7 nm presents the best integrative dielectric and electrical properties, which exhibits a dielectric permittivity of 2230.3 and a dielectric loss of 0.86 at 100 Hz.