柔性交联型聚酰亚胺气凝胶的制备及性能

利用溶胶-凝胶反应制备了聚酰亚胺凝胶,经过超临界干燥得到了聚酰亚胺气凝胶.研究了固含量和交联剂比例对气凝胶性能的影响规律.结果表明,聚酰亚胺气凝胶的密度和线收缩率都随着固含量和交联剂比例的增加而增加;随着固含量的增加,气凝胶的室温热导率呈现出先降低再增加的趋势(0. 026～0. 033W·m-1·K-1),气凝胶的力学刚度和强度明显提升;交联剂的加入,可以提高材料的韧性,断裂应变最高达21. 7%;制得的柔性聚酰亚胺气凝胶具有良好的热稳定性,是满足尖端武器以及空间飞行器对于轻质、柔性热防护要求的理想材料之一.

Preparation and Properties of Flexible Cross-linked Polyimide Aerogels

Polyimide aerogels were synthesized by sol-gel reaction, followed by supercritical drying. The effects of sol solid content and cross-linking agent ratio on performance of polyimide aerogels were investigated. The results showed that both the shrinkage and density of polyimide aerogels increased with increasing sol solid content and cross-linking agent ratio. With the increased sol solid content, the suitable thermal conductivity(0.026—0.033 W·m^-1·K^-1) declined at first and then increased, and the modulus and strength of polyimide aerogels was improved obviously. Introducing the cross-linking agent into molecular structure improved the toughness of polyimide aerogels, and the maximum value of break strain was 21.7%. The polyimide aerogels also showed high temperature stability. The good properties made them an ideal insulation for light weight and flexible thermal protection of advanced weapons and space vehicles.