采用溶胶凝胶法,以正硅酸乙酯和酚醛树脂为原料,在草酸的催化作用下,制备出了不含硫和氯等有害杂质的均相碳化硅先驱体,并在特定条件下,对所得先驱体进行烧结,使之转化为陶瓷.结果表明,预水解温度控制在40℃左右,时间为24h时,凝胶制备效果最佳;草酸与正硅酸乙酯的摩尔比为0.01左右时,可以使凝胶时间达到最短;溶胶凝胶法制得的先驱体呈黄色透明的玻璃态,其微观组成为几十纳米的微粒,树脂与SiO2可能通过氢键相互作用,有利于树脂在先驱体中均匀分布而形成均相先驱体;另外硝酸镍的加入对先驱体烧结过程中β-SiC的生成起到促进作用.

Based on aliphatic alcohol, alcohol amine and amine, a new mixed expander (NB) for polyurethane prepolymer was prepared. This expander is very useful for rapid solidification medical polyurethane materials without carcinogenic ingredient. Taking a commercially available expander(MB), which is mainly composed of 4,4'\|methylene\|bis(2\|chloroaniline)(MOCA), as a reference, the reactions of the both expanders and polyether\|based polyurethane prepolymer were traced by IR and GPC. Both systems showed similar solidification time, but the material based on NB, or N\|PU, have a better initial fluidity, which is convenient for clinical operation. The reactive degree of isocyanate groups is higher in N\|PU than in M\|PU(material based on MB). The average molecular weight of N\|PU is much higher than that of M\|PU. The stress\|strain curves of the material of N\|PU and M\|PU behaved like “C” and reverse “S” type respectively. N\|PU does not show obvious creeping phenomenon and is less rigid. Environmental adaptability of both materials is the same. Therefore, NB is suggested to be a substitute for MB.

A simplified model of polycarbosilane (PCS)precursor was carried out.On the base of it, Charlesby Pinner relationship was applied to the process of EB radiation curing of PCS fibers and a statistical analysis was made.The results show that, the measured data conform to the Charlesby Pinner relationship and in a large range of absorbed doses. the crosslinking degree and cracking degree of vinyl containing PCS (VPCS) fibers are approximately proportional to the absorbed dose .