超支化聚硼酸酯改性苯并噁嗪树脂阻燃性能研究

Flame retardancy of hyperbranched polyborate modified benzoxazine resin

苯并噁嗪是一种类似酚醛树脂的开环固化型热固性树脂,具有一定的耐热性和阻燃性,但在阻燃要求高的场合使用时,需要进一步改善其阻燃性、力学性能及工艺性。而已有的阻燃改性方法较难实现在提高树脂阻燃性的同时兼顾其力学性能和工艺性。采用一种具有增韧作用的耐高温超支化聚合物—超支化聚硼酸酯(HBPB),在改善苯并噁嗪树脂力学性能和固化工艺性的基础上对其进行阻燃改性。加入2.5或5.0wt%的HBPB后,苯并噁嗪树脂的800℃(氮气)残碳率可由46.0%提高至50.9%和54.8%;阻燃性能明显提升,由UL-94V1提高到UL-94V0级,苯并噁嗪树脂的极限氧指数也由24%增加到30%和33%。HBPB改性苯并噁嗪树脂燃烧产物表面形成的致密表面结构,是树脂阻燃性提高的重要原因。

Benzoxazine resin was a ring-opening thermosetting phenolic resin, but flame retardancy of the resin was still need to be improved in some occasion required high performance . Traditional modification methods were difficult to improve the flame retardancy, mechanical properties and processability, simultaneously. High thermal resistant hyper- branched polymer-hyperbranched polyborate （HBPB） was utilized to modify the flame retardancy of benzoxazine resin. Adding 2.5 or 5.0 wt% of HBPB, char yield of benzoxazine resin in 800 ℃ （nitrogen） was improved from 46.0% to 50. 9 and 54.8% respectively. The flame retardancy was also improved from the UL-94 V1 to UL-94 V0 level. And the limiting oxygen index was increased to 30%and 33% from 24%. The main reason for the improved flame retardancy was the denser surface structure of combustion product of HBPB modified benzoxazine resin.