酚醛树脂(PF)因其具有良好的耐热性能和机械性能而被广泛应用. 但其耐热性能已经满足不了现代航空航天技术的需求,研究发现,采用硼酸对酚醛树脂进行改性,可以制得具有优良耐高温性能的硼酚醛树脂(BPF). 采用硼酸酯法合成硼酚醛树脂,n(苯酚)∶n(甲醛)=1∶1.5时耐热性最佳. 热分析结果表明,合成的BPF在1000 ℃条件下的残炭率为78%,其耐热性能明显优于传统的酚醛树脂. 同时讨论了不同硼酸含量对BPF耐热性能的影响,当n(硼酸)∶n(苯酚)>0.33∶1时,残炭率趋于稳定. 此外,利用差示扫描量热仪(DSC)方法确定BPF预固化温度为160 ℃,后固化温度为220 ℃.
Phenolic resin(PF) is widely used due to its excellent heat resistance and mechanical properties.But its heat resistance cannot meet the demand of modern science and technology.Preparation of boron phenolic resin(BPF) with excellent high temperature resistance through borate esterification method, and when n(phenol)∶n(formaldehyde) is 1∶1.5, the corresponding BPF exhibits the best heat resistance.The thermal analysis results show that the char yield of BPF is 78% at 1000 ℃, which is better than those of traditional phenolic resin and commercially available boron phenolic resin.The influence of boric acid content on the heat resistance of BPF was also discussed.When n(boric acid)∶n(phenol) is more than 0.33∶1, the char yield of BPF tends to be constant.In addition, the pre-curing and the post curing temperatures of BPF determined by DSC analysis are 160 ℃ and 220 ℃, respectively.
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