【摘要】 聚酰亚胺(PI)气凝胶是一类密度低、机械性能好、隔热性能优异的多孔材料,通常使用昂贵的化学交联剂进行交联.氧化石墨烯(GO)是近年来广受关注的用于聚合物增强的纳米功能填料.以前报道的PI/GO复合材料多是纤维或膜的形式.为了获得PI/GO复合气凝胶,本文采用化学改性氧化石墨烯(m-GO)替代1,3,5-三(4-氨基苯氧基)苯(TAB)等常规的交联剂,使之与4,4′-二氨基二苯基醚(ODA)和3,3′,4,4′-联苯四羧酸二酐(BPDA)反应,制得了m-GO交联的PI气凝胶.GO的化学改性通过其与过量ODA在水热条件下反应实现.通过扫描电子显微镜(SEM)研究了PI/m-GO气凝胶的微观结构.分别通过氮气吸脱附测试、热重分析和热线法研究了m-GO对气凝胶的孔特性、热稳定性和热导率的影响.测试结果表明,所获得的PI/m-GO气凝胶保持了高的孔隙率、热稳定性和绝热性.压缩测试结果显示,与采用1.8%(质量分数,w)的TAB进行交联的PI气凝胶相比,仅用0.6%(w)的m-GO交联所获得的气凝胶具有更高的比杨氏模量(杨氏模量/密度)、比屈服强度(屈服强度/密度)和更小的体积收缩率.更多还原

【Abstract】 Polyimide(PI) aerogels, which are generally crosslinked using expensive chemical crosslinking agents, are novel porous materials with high strength, high heat resistance, high porosity, and low density.Graphene oxide(GO) is a functional nanofiller that has aroused wide interest in recent years. The reported PI/GO composites have mostly been in the form of fibers and films. In this study, PI/GO composite aerogels were obtained using chemically modified graphene oxide(m-GO) as the crosslinking agent, instead of traditional ones such as 1,3,5-triaminophenoxybenzene(TAB), by reaction with 4,4′-oxydianiline(ODA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride(BPDA). The chemical modification of GO was achieved by reacting GO with excess ODA using a hydrothermal method. The microstructures of the PI/m-GO aerogels were investigated using scanning electron microscopy(SEM). Nitrogen sorption tests, thermogravimetric analysis, and a hot-wire method were used to investigate the effects of m-GO on the pore properties, thermal stabilities, and thermal conductivities, respectively, of the resulting aerogels. The results show that the PI/m-GO aerogels are highly porous, thermally stable, and heat insulating. Compression tests showed that the PI aerogel prepared using0.6%(mass fraction, w) m-GO instead of 1.8%(w) TAB as the crosslinking agent had a higher specific Young′s modulus [Young′s modulus/density(ρ)] and specific yield strength(yield strength/ρ), and less shrinkage.更多还原