TDI modified polysilazane was synthesized by the reaction of toluene -2,4- diisocyanate ( TDI) and polysilazane ( PSN2) , which was then characterized by FT-IR, GPC and TGA. The influences of reaction conditions on the structure, molar mass, viscosity and thermal properties of the product were investigated. Experimental data showed that with the increase of TDI in the reaction system at the same temperature, the molar mass decreased, the molecular weight distribution narrowed and the viscosity increased. When adopting the same amount of TDI, the viscosity of the samples increased with the elevated reaction temperature. Besides, TDI modified-PSN2 showed higher thermal stability with less weight loss at the onset stage than original PSN2. And all the products possessed high ceramic yield above 80%.%采用甲苯二异氰酸酯( TDI)与聚硅氮烷PSN2反应,制备了异氰酸酯改性聚硅氮烷.用红外、凝胶渗透色谱及热重分析对反应产物进行了表征,比较了反应温度及原料比例对产物的结构、摩尔质量、黏度及热性能的影响.结果表明,在相同反应温度下,随着TDI用量增加,产物的摩尔质量减小,摩尔质量分布变窄,黏度增加；TDI用量相同时,产物黏度随温度升高而增大,但摩尔质量变化无明显规律.另外,随TDI用量增加,异氰酸酯改性聚硅氮烷前期的热失重减小,陶瓷产率有所升高,且均在80％以上.
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