Study On Preparation And Properties Of High Dielectric Polyethylene Hybrid Composites

With the rapid development of the electronic technology industry,traditional capacitor materials have become increasingly unsatisfactory.Therefore,how to increase the dielectric constant of capacitor materials,reduce dielectric loss,and increase energy storage density have become a research hotspot.High molecular polymers are widely used in capacitors and other fields due to their excellent chemical stability,easy processing,and low cost.However,such polymers generally have low dielectric constants,so how to increase the dielectric constant of polymers has become a new challenge.In this paper,low-density polyethylene is used as the polymer matrix,multi-walled carbon nanotubes?MWCNT?and barium titanate nanoparticles?BaTiO₃?was used as fillers,and ethylene-octene grafted glycidyl methacrylate?POE-GMA?elastomer is the compatilizer.Preparation of nanocomposites,and the effects of different nanoparticle content on the comprehensive properties of nanocomposites such as dielectric properties are studied.The specific research content is as follows:?1?Carbon nanotubes with carboxyl?MWCNT-COOH?were used to as fillers,by fixing the amount of POE-GMA elastomer in the system,and introduced them into the low-density polyethylene matrix?LDPE?.Finally,study the crystalline properties,dielectric properties and other comprehensive performance effects of MWCNT-COOH/POE-GMA/LDPE composites by adding different volumns of MWCNT-COOH.Through SEM,we can see that POE-GMA coated MWCNT-COOH has a good dispersion in the polyethylene matrix.The experimental results also found that at the same MWCNT-COOH content,the MWCNT-COOH/POE-GMA/LDPE composites have higher crystallinity and excellent mechanical properties than the MWCNT-COOH/LDPE composites.When the filler content at 5 wt%,the dielectric constant of MWCNT-COOH/POE-GMA/LDPE is 17 times than pure LDPE,and the dielectric loss is much lower than MWCNT-COOH/LDPE composites.In addition,it was found that the breakdown strength and energy storage density of the composites decreased significantly with the increase of the MWCNT-COOH filler content.?2?Barium Titanate?BaTiO₃?was used as filler.And surface modification of BaTiO₃ was carried out with hydrogen peroxide?H₂O₂?and silane coupling agent?KH-550?.Through the TGA,FTIR,and SEM proved that the surface modification of BaTiO₃ was successful.The BaTiO₃-NH₂ was introduced into the low-density polyethylene matrix?LDPE?,and the amount of POE-GMA elastomer in the system was fixed.Then study the crystallization properties,dielectric properties,energy density and breakdown strength of the added different content of BaTiO₃-NH₂ into the LDPE matrix.The results show that when the filler content was 10 wt%,the dielectric constant of BaTiO₃-NH₂/POE-GMA/LDPE nanocomposites was about 1.28 times higher than that of LDPE,and the dielectric loss was much lower than BaTiO₃-NH₂/LDPE composites.In addition,when the loading content at 10 wt%BaTiO₃-NH₂/POE-GMA/LDPE composite,the maximum breakdown strength was 350 MV/m and the maximum discharge energy density was 2.46 J/cm³,and the mechanical properties were also significantly improved.