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聚乙烯基倍半硅氧烷及其可瓷化复合材料的制备与性能
程治硚1, 王开石1, 匡松连1, 韩伟健2
1.先进功能复合材料技术重点实验室,航天材料及工艺研究所,北京 100076;2.中国科学院化学研究所,北京 100190
摘要:
以乙烯基三甲氧基硅氧烷(VTMS)为单体,采用水解缩合的方法制备了聚乙烯基倍半硅氧烷(PVSQ),对PVSQ的固化机制、固化温度以及热稳定性进行研究。结果表明以低毒性的乙醇取代甲苯为溶剂、能于150 ℃中温固化的PVSQ可作为硅基可瓷化防热复合材料的基体使用。通过SEM、EDS、XRD对添加TiB2、云母等成瓷填料制备的PVSQ复合材料的陶瓷化性能进行研究。结果表明材料在800~1 200 ℃热处理30 min后失重率仅为0.29%~4.15%,体积收缩率为5.20%~15.08%,高温下成瓷填料与材料热解产物之间发生原位陶瓷化反应,产生大量玻璃相起到基体桥接作用,促进尺寸、形状稳定的陶瓷体形成。
关键词:  聚乙烯基倍半硅氧烷  复合材料  可瓷化  失重率  尺寸稳定性
DOI:10.12044/j.issn.1007-2330.2019.01.010
分类号:
基金项目:
Synthesis and Properties of Polyvinylsilsesquioxane and Its Ceramifiable Composites
CHENG Zhiqiao1, WANG Kaishi1, KUANG Songlian1, HAN Weijian2
1.Science and Technology on Advanced Functional Composites Laboratory,Aerospace Research Institute of Materials & Processing Technology,Beijing 100076;2.Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190
Abstract:
Polyvinylsilsesquioxane(PVSQ) was synthesized with hydrolysis-polycondensation method from vinyltrimethoxysiloxane (VTMS),and the curing mechanism, curing temperature and thermal stability of PVSQ were studied.The results show that PVSQ,which use ethanol as solvent and be curable at 150 ℃,can be used as the matrix of silicone-based ceramifiable composites for thermal protection applications.Combined with ceramifiable fillers (e.g.,TiB2,mica,etc.),the in-situ ceramization process of PVSQ ceramifiable composites was studied by SEM, EDS and XRD.The results indicate that the weight loss of PVSQ composites is only 0.29wt% to 4.15wt% and the volumetric shrinkage is 5.20vol% to 15.08vol% when annealed at 800 to 1 200 ℃ for 30 min.The in-situ ceramization reaction take place between the ceramifiable fillers and the pyrolytic products of PVSQ at high temperatures,and generate a large amount of glassy phase for matrix bridging, which further leads to the formation of dimensionally-stable ceramic product.
Key words:  Polyvinylsilsesquioxane  Composites  Ceramization  Mass loss  Dimensional stability