Preparation And Properties Of Silicon Carbide Nanowires/polyvinylidene Fluoride Composites

Dielectric composites with excellent properties in all aspects are the key to the development of high-quality dielectric capacitors,So how to improve the dielectric properties and energy storage properties of dielectric composites has attracted extensive attention of researchers.A series of Si CNWs/PVDF binary composites,Si CNWs@Si O₂/PVDF composites and Si CNWs/T-Zn Ow/PVDF ternary composites were prepared by solution blending phase conversion method and hot pressing process.With polyvinylidene fluoride(PVDF)as matrix and silicon carbide nanowires(Si CNWs),core-shell silicon carbide nanowires@silica(Si CNWs@Si O₂)and tetraacicular zinc oxide whisker(T-Zn Ow)as fillers.The effects of surface modification,core-shell structure and multicomponent double nano fillers on the microstructure,and the corresponding macro dielectric properties and energy storage properties of PVDF matrix composites were investigated.To increase the compatibility between filler and matrix,Si CNWs and T-Zn Ow were modified by silane coupling agents KH550 and KH570,respectively.Typical core-shell structures were prepared by one-step thermal oxidation process Si CNWs@Si O₂nanowires,the thickness of Si O₂ shell increases with the extension of thermal oxidation time,when the thermal oxidation time is 10 h,the thickness of Si O₂ shell is 6.5 nm;PVDF matrix composites were synthetized by phase conversion method,and all nano fillers were blended with PVDF matrix;With the doping amount of Si CNWs increasing,the Si CNWs/PVDF binary composite appears obvious agglomeration,the dispersion of fillers in polymer matrix is greatly improved via the addition of core shell structure Si CNWs@Si O₂ and multicomponent double nano fillers Si CNWs and T-Zn Ow,the dispersion of filler in polymer matrix is greatly improved.Compared with Pure PVDF,the introduction of Si CNWs greatly ehances the dielectric constant of the composites.However,the dielectric loss and conductivity are large,the core-shell structure and multi-element double nano filler can effectively reduce the dielectric loss and conductivity while maintaining high dielectric constant,and significantly improve the breakdown strength of the composites.The energy storage density of Pure PVDF and series Si CNWs/PVDF binary composites is low,when the doping amount of nano filler is 25 wt%,the introduction of core shell structure with thermal oxidation time of 10 h Si CNWs@Si O₂ nanowires and multicomponent double nano filler with the ratio of Si CNWs to T-Zn Ow of 1:1,25wt%Si CNWs@Si O₂/PVDF(10h)composite and 25wt%Si CNWs/T-Zn Ow/PVDF(1:1)ternary composite under ultimate electric field strength,the maximum discharge energy densities obtained are 0.111 J/cm~3and 0.099 J/cm~3,the discharge efficiencies are 53.06%and 61.84%,respectively,which effectively improves the energy storage performance of the composite.