Synergistic Improvement Of Organic Silane And Layered Clay On The Tracking And Erosion Resistance Of Silicone Rubber

Silicone rubber is widely utilized in the field of outdoor high voltage insulation due to its advantages of light weight,outstanding electrical insulation properties and hydrophobicity,and is gradually replacing the traditional insulation materials.With increasing operating voltage level of the electric power system,silicone rubber is prone to causing the irreversible tracking and erosion failure during long-term service in the high voltage electric field,severely threatening the security and stability of the electric power system.Basically,the incorporation of a large amount of inorganic fillers(>40 wt%)is regarded as an efficient method to enhance the tracking and erosion resistance of silicone rubber.However,the processability,hydrophobicity and mechanical properties of silicone rubber are thus seriously deteriorated.Therefore,it is of great significance and challenge to effectively improve the tracking and erosion resistance of silicone rubber.In this work,high temperature vulcanized silicone rubber(HTVSR)with excellent tracking and erosion resistance was successfully prepared with simultaneous incorporation of organic silane and layered clay.The possible mechanism of organic silane/layered clay on the tracking and erosion resistance of HTVSR was further studied.The main contents and results are listed as follows:(1)HTVSR with desirable tracking and erosion resistance was prepared by incorporating vinyltriethoxysilane(Vi TES)and layered Mg-Al double hydroxide(LDH).The effect of Vi TES/LDH on the tracking and erosion resistance,curing properties,crosslinking density and mechanical properties of HTVSR was investigated.It was found that Vi TES and LDH synergistically enhanced the tracking and erosion resistance of HTVSR.With addition of 3.33 phr Vi TES and 5.00 phr LDH,the anti-tracking performance of HTVSR reached the 1A 4.5level,and the eroded mass was merely 0.3%.The results of scanning electron microscopy and equilibrium swelling showed that Vi TES improved the dispersion of LDH sheets in the HTVSR matrix and increased the crosslinking density of HTVSR.(2)The effect of Vi TES/LDH on the morphology and chemical composition of the superficial track residue,anti-plasma irradiation performance and thermal stability of HTVSR was studied by scanning electron microscopy-energy dispersion X-ray spectrometry,attenuated total reflection-Fourier transform infrared spectrometry,plasma irradiationtreatment,thermogravimetry and thermogravimetry-Fourier transform infrared spectrometry.The possible synergistic mechanism of Vi TES/LDH on the tracking and erosion resistance of HTVSR was further explored.It was indicated that Vi TES enhanced the interfacial interaction between HTVSR and LDH,and the side methyl oxidation as well as thermal degradation of the HTVSR backbone were suppressed.Meanwhile,under the high voltage arcing discharge,LDH facilitated the formation of a compact barrier layer consisting of bimetal mixed oxides on the HTVSR surface,exerting prominent lamellar barrier effect and inhibiting the further degradation of HTVSR and the generation as well as development of electrical tracking.(3)Platinum nanoparticles immobilized on montmorillonite(Pt@CTAB-MMT)were prepared by the in-situ reduction of chloroplatinic acid hexahydrate on the intercalated montmorillonite lamellas with sodium citrate tribasic.The structure of Pt@CTAB-MMT was characterized by Fourier transform infrared spectrometry,X-ray diffraction,scanning electron microscopy,transmission electron microscopy and thermogravimetry.The effect of3-aminopropyltriethoxysilane(AS)and Pt@CTAB-MMT on the tracking and erosion resistance,curing properties,mechanical properties and thermal stability of HTVSR was investigated.It was found that AS and Pt@CTAB-MMT synergistically improved the tracking and erosion resistance of HTVSR.With addition of 1.00 phr AS and 0.05 phr Pt@CTAB-MMT,the anti-tracking performance of HTVSR reached the 1A 4.5 level,and the eroded mass was only 0.4%.The possible synergistic suppression mechanism of AS/Pt@CTAB-MMT on the tracking and erosion of HTVSR was further studied by scanning electron microscopy-energy dispersion X-ray spectrometry,thermogravimetry and Raman spectrometry.Under the high voltage arcing discharge,AS and the high-activity platinum nanoparticles immobilized on Pt@CTAB-MMT synergistically facilitated the radical crosslinking reaction of the HTVSR molecular chain,resulting in the formation of a dense ceramic barrier layer on the surface of HTVSR.Meanwhile,as the carrier of Pt@CTAB-MMT,MMT possessed prominent lamellar barrier effect,therefore protecting HTVSR from further arc ablation and inhibiting the generation as well as development of electrical tracking.