Modification Of Waste Silicone Rubber Composite Insulator Power And Application In Ethylene Propylene Diene(EPDM)

Silicone rubber composite insulators due to the excellent insulation and pollution resistance have been widely used for outdoor high voltage application with the rapid development of the grid in China.With the approaching of the service life,a large number of composite insulators were replaced.Waste composite insulators not only occupy a lot of space,but also cause environmental pollution.Besides,the production cost of silicone rubber is high.Therefore,it is of great economic and ecological benefits to rationally make use of waste silicone rubber composite insulators.In this paper,silicone rubber composite insulators were first physically crushed.Waste rubber powder was added to EPDM to prepare composite materials.However,the cross-linked waste rubber powder that had low surface reactivity and polymeric matrix typically have lower mechanical properties due to lack of strong interfacial bonding.So,the surface and interface modification for waste powder should be carried out.The results obtained in this paper were as follows:?1?Waste silicone rubber composite insulator powder?WSP?was firstly analyzed by ATR-FTIR,Solid-state ²⁹Si NMR spectroscopy,TGA,EDS,SEM and laser particle size analyzer.The results showed the compositions of silicone rubber composite insulators included silicone rubber,white carbon black?SiO₂?and alumina trihydrate?the content was about 45%?.SEM showed that the powder was highly irregular agglomeration and particle size distribution testing showed that the average particle size was 13 um.?2?WSP was oxidized by using UV,UV-Fenton and H⁺/H₂O₂ surface oxidation approaches and subsequently grafted using 3-methacryloxypropyltrimethoxysilane coupling agent?KH570?to introduce functional reactive groups on the surface.The modification effects were evaluated by ATR-FTIR,Solid-state ²⁹Si NMR spectroscopy,TGA and SEM.The results showed that WSP could be oxidized by the three methods.WSP-H⁺/H₂O₂-KH570 displayed the maximum peak intensity of C=O and C=C,indicating that the oxidation effect of this approach by using acidic H₂O₂ solution and subsequently grafting of KH570 was best.?3?The modified WSP?WSP-H⁺/H₂O₂-KH570?was incorporated in the EPDM matrix and the properties of EPDM/WSP-H⁺/H₂O₂-KH570 and EPDM/WSP composites were investigated and compared.The curing time of EPDM/WSP-H⁺/H₂O₂-KH570 blend?90/10?was shortened.The physical properties of EPDM/WSP-H⁺/H₂O₂-KH570?90/10?blend revealed an observed improvement with up to 15.6%increase in tensile strength,10.2%increase in elongation at break and 3%increase in tear strength compared with those of corresponding compositions of EPDM/WSP blends.The TGA analysis showed that the EPDM/WSP-H⁺/H₂O₂-KH570 blend?90/10?had higher thermal stability at the decomposition stage of 210-380 ? compared with EPDM/WSP blends.DMA result displayed a tan ? peak,indicating that EPDM and WSP-H⁺/H₂O₂-KH570 were better miscible with the blend ratio?90/10?.The SEM photographs of the EPDM/WSP-H⁺/H₂O₂-KH570 displayed a relatively smooth surface with dispersed particles compared with EPDM/WSP.?4?In order to avoid the production of acidic waste solution in the modification process,the waste powder was firstly mixed with hexamethylene tetramine/iron dichloride/ferric chloride?mixed modifier?.The modified powder was added into EPDM to prepare the blends.The influence of mixed modifier 'modified waste powder on the properties of the blends was investigated.The physical properties of EPDM/WSP-mixed modifier?90/10?blends revealed an improvement with up to 11.8%increase in tensile strength,2.7%increase in elongation at break and 2.4%increase in tear strength,indicating that the mixed modifier was effective modifier for WSP.DMA result displayed a tan ? peak,indicating that EPDM and WSP-mixed modifier were better miscible with the blend ratio?90/10?.This was also consistent with the results of SEM analysis.?5?Two series of EPDM/WSP-H⁺/H₂O₂-KH570 and EPDM/WSP-mixed modifier blends were prepared.EPDM/WSP-H⁺/H₂O₂-KH570 blends showed more excellent mechanical properties and thermal stability.The EPDM/WSP-H⁺/H₂O₂-KH570 showed relatively smooth surface with uniformly dispersed particles.However,in consideration of the treatment process,the modified method using hexamethylene tetramine/iron dichloride/ferric chloride is more simple and environmentally friendly.