Research Of Synthesis And Modification Of High Temperature Silicone Resin

In recent years, with the development of technology in aerospace and military industry, the heat-resistant of ordinary silicone resin has been far from satisfying the requirements of these fields. These areas urgently need a kind of silicone resin which has a performance of high temperature. The reason that temperature of silicone adhesive is its degrading at high temperature, and the main reason of degradation is that main-chain is not strong in the structure of silicone, which can fracture when under attacking. So the temperature resistance of adhesive will decreased rapidly. This paper focuses on the problem about main-chain of silicone and studies silicone modified by inorganic materials. In ensuring the viscosity and the strength of silicone, we make the heat resistance better by improving the stability of main-chain.First, we synthesized the common silicone resin. This paper choose condensation to prepare the silicone resin from kinds of methods of synthesis, such as condensation, catalytic addition and peroxide oxidation. Condensation is that chlorosilane hydrolyzed silanol, then it generated silicone resin by polycondensation. In the experiment, the heat resistance of silicone resin were characterized and analyzed by IR and TG. The result showed that silicone resin containing benzene ring has good heat resistance, which can be used at 350℃in a long time. In addition, the paper also done some research about monomer ratio, solvent, ethanol, deionized water and hydrolysis temperature to effect of silicone resin, and found the best reaction conditions, which is that hydrolysis temperature was between 5℃to 10℃; hydrolysis time was about 40 min; condensation reaction time was 2h; condensation time was 55℃; the molar ratio of deionized water and chlorine atoms was about 7:1;solvent volume is 2 times of the total monomer, and the volume ratio of acetone and xylene was 1:10.Second, this paper do some research on the modification of silicone resin by glass. Because of the low reactivity of boric acid, the paper use boron-containing glass to modify the silicone resin, which can improve the temperature performance of silicone, shorten curing time and lower curing temperature. The temperature of modified silicone resin had reached to 550℃, and the curing time was only 21.6h at room temperature.At last, the paper researched the modification of boric acid to silicone resin. To the problem that modified materials of silicone are mostly organic materials, the paper prepared silicon-boron by condensatation with boric acid and chlorsilane, and characterize the modified silicone by IR and TG. The result show that decomposition temperature of silicone has reached to 490℃. Other, we also research the effect of boric acid consumption, reaction time, reaction temperature to the yield and performance of silicone resin. The result showed that the best reaction temperature was 90℃and reaction time was 6.5h.