Preparation And Characterzation Of Expansion Flame Retardant And Ceramifiable Silicone Rubber

Silicone rubber has been widely used in electronic appliances,electric wire and cable,aerospace,medicine and health,due to the advantages of high thermal stability,low heat release rate,non-toxic and aging resistance,etc.Its molecular main chain is Si-O structure,and the limit oxygen index of silicone rubber is higher compared to other main chains.However,silicone rubber will continue to burn when exposed to flame,so flame retardant modification is required.In this study,the high temperature vulcanized silicone rubber was studied in intumescent flame retardant system and vitrified system.Finally,the expansion/ceramic silicone rubber composites were studied systematically.In the first section,high temperature vulcanization silicone rubber(HTV-110)was used as material,aluminum hypophosphite(AHP)and expandable graphite(EG)were used as expansion flame retardants to study different factors' impacts on the flame retardant effect of silicone rubber.And the flame retardant property,mechanical property,thermal analysis and expansion character of silicone rubber composite materials were analyzed.The results revealed that the flame retardant property of silicone rubber composites improved tremendously,after adding aluminium hypophosphite into expandable graphite system layer strength improved,and expansion flame retardant had a good effect on the flame retardant property of silicone rubber.What's more,the vertical combustion can reach the V-0 level.In the second section,the ceramic properties of silicone rubber were studied.In order to prepare ceramic silicone rubber composite materials,AHP and Mica were used as porcelain-forming fillers and glass powder was used as fluxing agent.And X-ray diffraction(XRD),scanning electron microscopy(SEM),mechanical properties,thermogravimetric analysis(TGA),and other ways of characterization were used.The results show that AHP acts as a flux at low temperature and can effectively reduce the ceramic temperature.On the other hand AHP/Mica composites have better properties in strength than pure silicone rubber,and ceramic increased with increasing temperature.When adding 15 times of Mica alone,the compression strength is 8.31 MPa under 1000?,however when 10 times AHP/5 times Mica are used,the compression strength can reach 14.46 MPa,increased by 42.5%In the third section,silicone rubber expansions into ceramic were studied.Aluminum hypophosphite and mica were adopted to synthesis silicone rubber composites and to the impacts of silicone rubber composites were explored by changing the flux of the glass powder content.The experiment results showed that with the increase of Frits,the degree of crystallization decreases.The expansion started at 850? and the expansion increased with temperature,when the temperature up to 950?,the volume expansion to 157%,and the compression is 2.33MPa,however the mechanical performance was obviously reduced.After adding 6 times of silicone oil,the tensile strength increased from 2.94MPa to 3.65MPa and the hardness of shore hardness decreased from 75 to 64,what's more it did not affect its ceramic expansion behavior in high temperature.