Preparation Of Functional Organic-inorganic Hybrid Low-melting Glass And Its Effect On The Tracking And Erosion Resistance Of Addition Liquid Silicone Rubber

Silicone rubber has excellent high and low temperature resistance,hydrophobicity and recovery of hydrophobicity and so on.It is gradually replacing the traditional insulating materials,such as glass and ceramic.However,silicone rubber is easily subjected to the tracking and erosion in the long-term operation so as to lose its electric insulation property.Nowadays,the mechanical property and hydrophobicity of silicone rubber might decrease by the heavy load and high polarity of inorganic anti-tracking and erosion additive,and the common organic anti-tracking and erosion additive would decrease the hydrophobicity of silicone rubber owing to the addition of the polar groups.Therefore,it is meaningful for the development of silicone rubber to not only enhance the tracking and erosion resistance of silicone rubber,but also improve its mechanical and hydrophobic property.In this dissertation,polyphenylsilsesquioxane terminated with methyl and vinyl groups,an organic-inorganic low-melting glass(PhLMG),was prepared,and its effect on tracking and erosion resistance of silicone rubber was investigated.Then,fluorine-containing polyphenylsilsesquioxane,an organic-inorganic low-melting glass(FPLMG),was prepared.The effect of FPLMG on the hydrophobicity and tracking and erosion resistance of silicone rubber was studied.At last,the synergistic effect of FPLMG and ureido-containing MQ silicone resin(U-MQ)on the tracking and erosion resistance of silicone rubber was investigated.The main research contents and results are listed as follows:(1)Polyphenylsilsesquioxane terminated with methyl and vinyl groups,an organic-inorganic low-melting glass(PhLMG),was prepared by hydrolysis-condensation of phenyltriethoxysilane,hexamethyldisiloxane(MM)and divinyltetramethyldisiloxane(ViMMVi).PhLMG was characterized by Fourier transform infrared spectrometry(FT-IR),1H nuclear magnetic resonance spectrometry(1H-NMR),X-ray diffraction(XRD),gel permeation chromatography(GPC),thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC).The effect of PhLMG on tracking and erosion resistance and mechanical property of ALSR was investigated.The results demonstrated that residual silanol groups of PhLMG decreased and even disappeared with terminating agents increasing,and its molecular weight and thermal stability decreased.PhLMG could improve the tracking resistance and mechanical properties of ALSR.When the molar ratio of terminating agents(composites of MM and ViMMVi)to PhTES was 0.05,ALSR/Ph LMG had good tracking and erosion resistance property.(2)Fluorine-containing polyphenylsilsesquioxane,an organic-inorganic low-melting glass(FPLMG),was prepared by the hydrolysis-condensation of PhTES,vinyltriethoxysilane(ViTES)and tridecafluorooctyltriethoxysilane(FAS).FPLMG was characterized by FTIR,1H-NMR,GPC,TG,DSC and XRD,and its effect on the mechanical property,hydrophobicity,thermal stability and tracking and erosion resistance of ALSR was studied.The results indicated that FPLMG possessed amorphous ladder-like structure.The molecular weight and glass transition temperature of FPLMG increased and thermal stability decreased with the increase of FAS content.The tracking resistance and hydrophobicity of silicone rubber were effectively enhanced by FPLMG.However,the serious erosion of ALSR still existed,which was needed to be further improved.When the content of FAS was 5.7 mol%,ALSR/FPLMG successfully passed the 6 h incline plane tests.TG and TG-FTIR showed that FPLMG with low FAS content formed densely protective layer on the surface of ALSR.ALSR was mainly subjected to the cleavage of side methyl groups and thermal degradation of backbone.When the content of FAS was excessive,the protective layer formed by FPLMG was destroyed.The side methyl groups mainly suffered from the oxidation degradation instead of cleavage.Besides,the hydrophobicity of ALSR was improved when the FAS content of FPLMG increased.(3)The effect of FPLMG and U-MQ on the tracking and erosion resistance of ALSR was studied.The results indicated that FPLMG and U-MQ had excellent synergistic effect on improving the tracking and erosion resistance of ALSR.ALSR/FPLMG/U-MQ passed the 1A 4.5 kV level in incline plane test,and the eroded mass ratio declined to 0.2 %,compared with 2.5 % of ALSR,3.0 % of ALSR/FPLMG and 2.0 % of ALSR/U-MQ.TG and TG-FTIR results demonstrated FPLMG and U-MQ could effectively delay the oxidation degradation of side methyl groups and suppress the thermal degradation of backbone.Cone calorimetric test and plasma treating test also manifested that FPLMG and U-MQ possessed good synergistic effect on the flame retardancy and anti-plasma radiation of ALSR.