| Room temperature vulcanized foamed silicone rubber is a kind of sealing buffer material which can be foamed at room temperature.In the preparation process,if the foaming rate is too fast and the cross-linking rate is too slow,the gas will spill over the surface of the material and it is difficult to control the stable formation of the pore structure.However,if the cross-linking rate is too fast and the foaming rate is too slow,the silicone rubber matrix with larger viscosity will be formed,and it is more difficult to form the bubble structure.That is to say,in the process of preparing foamed silicone rubber by chemical foaming method,the matching of vulcanization rate and foaming rate is difficult to control.Therefore,it is still a research direction worthy of further exploration to prepare a kind of silicone rubber foam material with excellent performance and stable foaming in place at room temperatureBased on the α,ω-dihydroxy polydimethylsiloxane,hydroxyl silicone oil,silica powder,vinyl polysiloxane,MQ silicone resin,methyl hydrogen silicone oil,platinum catalyst,inhibitor,etc.as the main raw material was prepared by foam of two-component RTV silicone rubber,and through hydrogen by silicon hydrogen addition reaction and condensation dehydrogenation reaction to get foam silicone rubber material.The effects of platinum catalysts and different kinds of reaction functional groups on the structure and properties of foamed silicone rubber were studied.The results showed that the selection of platinum catalyst and the appropriate ratio of reaction groups had a great influence on the properties of the two-component RTV foamed silicone rubber.Through the characterization of reactants and reaction products by FTIR,the foaming and cross-linking reaction of silicone rubber under the action of platinum catalyst has been completed.Firstly,the influence of the amount of platinum catalyst on the foaming silicone rubber was studied.The results showed that when the platinum content was 1200ppm,the comprehensive properties of the foaming material reached the optimal.TGA results showed that the thermal stability was also excellent at this time,with the initial decomposition temperature reaching 494℃ and the residual weight retention rate reaching 71.66%.Meanwhile,the crosslinking density of the product reached a maximum of 15.97×E-5 mol/mL,which improved the stability of the pore structure.The micromorphology was observed by SEM,and the conclusion was drawn that when the addition amount of platinum catalyst was 1200ppm,the nucleation density of foamed silicone rubber was the highest and the average pore diameter was 0.309mm.Then by setting the appropriate orthogonal experiment table,the control ratio of different functional groups,get a series of different foam bubble pore structure and properties of room temperature vulcanized silicone rubber.SEM showed that the average pore diameter was the smallest when the orthogonal experimental conditions were A1B1C1,and the average pore diameter was the largest when the orthogonal experimental conditions were A1B3C3,and the order of the influence of different functional groups on the pore size was determined as follows:terminal hydroxyl content>terminal vinyl content>silicon-hydrogen bond content.A series of room-temperature vulcanized foamed silicone rubber with different pore structures and properties were prepared in this paper,which laid a foundation for the material development in special application scenarios.It can be seen from the element analysis test and vertical burning test,the foamed silicone rubber material prepared by room temperature vulcanization has good thermal stability,and after ablation products contain a large amount of SiO2 powders,according to the standard of vertical burning test,a single sample after each on fire flaming combustion time less than 10 seconds,the flame retardant level is FV-0,which means that the preparation of silicone rubber foam materials has a wider application in heat sealing and flame retardant. |
PDF Full Text Request