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柔性有机硅气凝胶复合材料的制备及性能研究
姚鸿俊1,王飞2,朱召贤1,董金鑫1,龙东辉1
1.华东理工大学,化学工程联合国家重点实验室,上海 200237;2.中国空间技术研究所,北京 100074
摘要:
以甲基三甲氧基硅烷(MTMS)和二甲基二甲氧基硅烷(DMDMS)为前驱体,通过溶胶-凝胶、常压干燥制备出柔性有机硅气凝胶,研究了MTMS与DMDMS的摩尔比对其化学组成和微观结构的影响;采用莫来石纤维毡作为增强体,制备出密度为0.25 g/cm3的柔性有机硅气凝胶复合材料。实验结果表明,所制复合材料具有优异的热稳定性,其室温热导率在0.03 W/(m·K)以内;当MTMS和DMDMS的摩尔比为3.8∶1.2时,复合材料的均匀伸长率达3.6%、残重率达82.4%;复合材料经高温处理后,有机硅气凝胶转变为无机SiO2气凝胶,较好地保持煅烧前的微观形貌和隔热性能;通过500 s石英灯静态加热,发现复合材料的表面有陶瓷化反应,厚度方向无收缩,背部温升81℃,表现出烧蚀/隔热的双重特性。
关键词:  有机硅气凝胶  纤维增强复合材料  低密度  隔热  烧蚀
DOI:10.12044/j.issn.1007-2330.2019.06.005
分类号:TB332
基金项目:
Preparation and Properties of Flexible Silicone Aerogel Composites
YAO Hongjun1,WANG Fei2,ZHU Zhaoxian1,DONG Jinxin1,LONG Donghui1
1.State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237;2.China Academy of Space Technology, Beijing 100074
Abstract:
Flexible silicone aerogels were prepared through sol-gel polymerization of methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS), followed by ambient pressure drying. The effects of mole ratio of MTMS to DMDMS on the chemical composition and microstructure of silicone aerogels were analyzed. Furthermore, flexible aerogel composites with a low density of around 0.25 g/cm3 were prepared by using mullite fiber blanket as structure reinforced agent. The as-prepared composites have excellent flexibility, good thermal stability and low room-temperature thermal conductivity below 0.03 W/(m·K). When the ratio of MTMS to DMDMS was optimized to 3.8∶1.2, the resultant composites had the highest tensile elongation of 3.6% and char yield of 82%. After calcination of the composites, the silicone aerogels were convent into inorganic SiO2 aerogels with similar microstructure and thermal insulation. In static assessment of quartz lamp heating for 500 s, the surface of composites occurred ceramic reaction without obvious shrinkage at thickness direction, and there was 81℃-rise of their back temperature, demonstrating the combined functions of organic ablator and inorganic insulation properties.
Key words:  Silicone aerogel  Fiber-reinforced composites  Low density  Insulation  Ablation