Research On Preparation And Thermal Properties Of Silicone-phenolic Hybrid Resin

Phenolic resin has excellent properties of flame resistance,high temperature resistance,corrosion resistance,and other aspects.It can be used as heat-resistant coating,adhesive and matrix resin of composite in the fields of thermal protection of chemical industry and aerospace.Silicone resin is a kind of cross-linked polymer with a framework which is connected alternately by silica and oxygen.The high bond energy of Si-O bond and flexible molecular structure make it having good thermal stability,weather resistance and flexibility.In this paper,the environment-friendly phenolic system and silicone resin were copolymerized to prepare silicone-phenolic hybrid resin.The influence of reaction parameters on structure and thermal properties of hybrid resin was studied.Furthermore,structure transformation of hybrid resin after pyrolysis and thermal degradation reaction were analyzed.Firstly,resorcinol-terephthalaldehyde resin?RT?with many benzene ring structures was synthesized,and silicone prepolymer?SP?was prepared by the reaction of methyltriethoxysilane?MTES?and 3-aminopropyl triethoxysilane.The silicone-phenolic hybrid resin?SPRT?was prepared by the copolymerization of RT with SP.The synthesized RT and SPRT were thermally cured in air.In this paper,the structure and thermal properties of silicone-phenolic hybrid resin were controlled by tailoring the amount of APTES and the ratio of phenolic resin to methyltriethoxysilane?MTES?,to solve the problem of phase separation of silicone-phenolic hybrid resin.The comprehensive performance of silicone-phenolic hybrid resin was improved by incorporation of APTES in the reaction system.The results obtained by scanning electron microscopy?SEM?observation and analyses of energy dispersive X-ray spectrometer?EDS?showed,that the distribution of C,N,O and Si in SPRT samples was uniform,and no phase separation was observed.The chemical structures of RT and SPRT were analyzed by FT-IR and XPS.Thermogravimetric?TG?results indicated that the mass retention of RT and SPRT at 1000? in inert atmosphere was 66.5% and 73.4%,respectively.The mass retention of SPRT at 1000? was 35.2% in air.On the basis of the preparation of SPRT,the carbonization sample C-SPRT of silicone-phenolic hybrid resin was prepared by high temperature thermal conversion of SPRT in N₂ atmosphere,to further improve its heat and oxygen resistance.The results of X-ray photoelectron spectroscopy?XPS?showed that SPRT has formed the structure of Si O₂ and polyaromatic ring with oxygen atom after high temperature heat treatment.The SPRT sample was tested by TG-FTIR,and the results indicated that the decomposition of SPRT samples in inert atmosphere would produce CO,CO₂,H₂ O,CH₄ and alcohols.TG results in air showed that the initial thermal decomposition temperature(T_5%)of C-SPRT was 628?,which was higher than the corresponding SPRT sample about 282?,and the mass retention rate was 48.4% at 1000?.