中文摘要：

首先制备可均匀分散于N,N＇-二甲基甲酰胺（DMF）中的氧化石墨烯片（GO）,将GO的DMF分散液与聚酰胺酸（PAA）的DMF溶液进行液相共混,然后流延成膜制得GO-PAA复合薄膜,最后将PAA进行热酰亚胺化处理,在此过程中GO被原位还原为石墨烯（GS）,从而获得石墨烯-聚酰亚胺（GS-PI）复合薄膜.将具有不同石墨烯含量的复合薄膜样品分别进行热重分析及力学和电学性能测试.结果表明,随着GS含量的增加GS-PI复合薄膜的表面电阻率逐渐降低.使用1.0 wt%的GO制备的GS-PI复合薄膜的表面电阻率降至106Ω,此后趋于稳定.在GO不高于0.6 wt%的用量下制备的复合薄膜的拉伸强度和断裂伸长率可发生同步增加;至GO用量为0.6 wt%二者的增强都达到最高值.此后继续增加GS含量,拉伸模量持续提高,断裂伸长率出现下降.在实验涉及的范围内,复合薄膜保持良好的延展性和热稳定性.

英文摘要：

Graphene oxide （GO） sheets were first synthesized through oxidation of natural graphite by a modified Hummers method, and then their homogeneous and stable dispersion in N, N＇-dimethylformamide （DMF） was obtained. Stable and homogeneous solution mixtures of GO and PAA （polyamic acid） in DMF at different mass ratios of GO/PAA were readily prepared. Uniform composite films of GO-PAA were subsequently prepared by solution casting. PAA was turned to polyimides （PI） and GO reduced in situ to graphene （GS） at the same time by a subsequent thermal imidization of GO-PAA films, leading to composite films of GS-PI. Electrical resistivity, thermal stability and mechanical property of GS-PI films were studied. The results indicate that the surface resistivity of GS-PI films was significantly decreased with the increase in GS content,lowered to about 10^6 Ω,the standard of the anti-static electricity film,in the film prepared with 1.0 wt% of GO in GO- PAA. The tensile strength and the elongation at break of GS-PI composite films were both increased with increase in GS content,reached their maxima in the film prepared with 0.6 wt% of GO in GO-PAA,followed by regular decreases with further increase in GS. Different from the tensile strength and the elongation at break,the tensile modulus of GS-PI was in constant increase with GS content in the film. An increase of 37% was detected in GS-PI film prepared with 3.0 wt% of GO. Moreover,the ductility and the thermal stability of GS-PI were well kept in all the composite films regardless of its GS content.