【摘要】 在聚酰亚胺（PI）制备阶段,将SiO₂气凝胶粉末加入到N,N-二甲基乙酰胺（DMAc）和聚酰胺酸（PAA）中分别制备复合薄膜,对比研究了在PAA聚合前后加入SiO₂气凝胶粉末对PI热稳定性及隔热性能的影响。扫描电子显微镜分析表明在PAA聚合前加入SiO₂气凝胶粉末能够使气凝胶在PI基体中分散均匀,形成均匀的热阻网络,同时也保留了气凝胶的孔洞结构。热失重分析表明PI的热稳定性随着SiO₂气凝胶含量的增加而提高,当SiO₂气凝胶含量为20%时（wt,质量分数,下同）,聚合前加入SiO₂气凝胶制备的复合薄膜热失重初始温度提高了180℃,而聚合后加入SiO₂气凝胶则只提高了87℃。导热系数测试结果表明SiO₂气凝胶的加入提高了PI的隔热性能,当SiO₂气凝胶含量为20%时,聚合前加入气凝胶制备的复合薄膜的导热系数为0.071W/（m·K）,聚合后加入气凝胶制备的复合薄膜导热系数为0.1343W/（m·K）。说明在PAA聚合前加入SiO₂气凝胶粉末更能发挥气凝胶的优异性能。更多还原

【Abstract】 In the polyimide（PI）preparation stage,SiO₂ aerogel powders was added to N,N-dimethylacetamide（DMAc）and polyamic acid（PAA）to prepare composite films respectively.The effects of adding aerogel powders before and after polymerization on the thermal stability and thermal insulation properties of PI were compared.The scanning electron microscopy（SEM）showed that the addition of aerogel powders before PAA polymerization allowed the aerogel to disperse uniformly on the polyimide matrix,forming a uniform network of thermal resistance while retaining the pore structure of the aerogel.The thermogravimetric（TG）curve shown that the addition of SiO₂ aerogel improved the thermal stability of PI.When the addition amount was 20 wt%,the initial temperature of the weight loss of the composite film prepared by adding aerogel before polymerization was increased by 180℃,while adding aerogel after polymerization was increased by 87℃.The thermal conductivity test shown that the addition of SiO₂ aerogel improved the thermal insulation of PI.When the addition amount was 20 wt%,the thermal conductivity of the composite film prepared with adding aerogel before polymerization was 0.071 W/（m·K）,while adding aerogel after the polymerization was 0.1343 W/（m·K）.It was indicated that the addition of SiO₂ aerogel powders before PAA polymerization can better exert the excellent performance of aerogel.更多还原