TiB_2增强酚醛泡沫的制备及性能

为提高酚醛泡沫材料的耐高温性能和高温裂解前后的力学性能,通过物理共混法在发泡酚醛树脂中添加二硼化钛(TiB_2)无机填料制备了酚醛/TiB_2泡沫复合材料。研究了泡沫复合材料的固化过程和在1 000℃下裂解前后的微观结构,以及不同的TiB_2颗粒含量对泡沫复合材料的热物理性能、裂解前后力学性能的影响。结果表明,添加的TiB_2颗粒并不能被引入到酚醛树脂的分子链中,但是能够与酚醛树脂裂解释放出的含氧气体发生氧化还原反应,将裂解气体中的C和O元素吸收并转化为无定形碳和TiO_2等固相产物,从而提高了酚醛泡沫的残炭率和裂解后的力学性能。随着TiB_2含量的增加,泡沫复合材料的残炭率以及裂解前后的表观密度、比压缩强度和比弯曲强度均呈上升趋势,其中裂解后的强度上升更为明显。当TiB_2用量为30份时,酚醛泡沫复合材料在1 000℃下裂解产物的残炭率、比压缩强度和比弯曲强度分别比纯酚醛泡沫材料提高了39.2%,76.5%和43.9%。

Preparation and Properties of Phenolic Foams Reinforced with TiB2 Particles

In order to improve high-temperature resistance of phenolic foams and their mechanical properties before and after high-temperature pyrolysis,phenolic/TiB2 foam composites were prepared by physical blending method with TiB2 particles. The curing process of the foam composite and its microstructure before and after pyrolysis at 1000℃ were studied. Effects of TiB2 con-tent on thermal physical properties and mechanical properties before and after pyrolysis at 1000℃ of the foam composites were also investigated. The results show that TiB2 particles can not be introduced into molecular chains of phenolic resin but induces oxidation-reduction reaction with pyrolysis oxygenic volatiles derived from phenolic resin at high temperature,which can absorb and transform the carbon and oxygen elements into amorphous carbon and TiO2 and increase the char yield and the strength of pyrolysis products. With the increase of TiB2 contents,the char yield and the specific compressive strength and specific blending strength before and af-ter pyrolysis are increased,the strengths after pyrolysis are improved more obviously. When the content of TiB2 is 30 phr,the char yield,specific compressive strength and specific blending strength of the pyrolysis foam composite residues at 1000℃ are increased by 39.2%,76.5% and 43.9% compared with those of pure phenolic foam.