碳纤维-氧化石墨烯/环氧树脂复合材料的制备及表征

采用改进的Hummers法制备了五种具有不同氧化程度的氧化石墨烯（GO）。借助元素分析、X射线光电子能谱及FTIR红外光谱测试对所制备GO的组成及结构衍变进行了表征。利用光学显微镜对不同GO在固化剂异佛尔酮二胺（IPDA）中的分散状态进行观察，并将分散效果最佳的GO试样用于改性碳纤维/环氧树脂（CF/EP）复合材料。结果表明，随着氧化剂用量及反应时间的增加，GO的氧化程度也随之增加。在氧化程度较低时，GO表面官能团主要以羰基、羧基和酚羟基为主。随着氧化程度的不断提高，GO表面官能团主要为醚、环氧和醇羟基结构。GO在IPDA中的分散状态与其氧化程度密切相关，氧化程度最低和最高的GO均出现明显的聚集现象。另外，GO表面在分散过程中可被IPDA化学改性。在EP基体中加入分散效果最佳的GO（0.2wt%）后，与CF/EP复合材料相比，CF-GO/EP复合材料的弯曲强度、层间剪切强度和Ⅱ型层间断裂韧性分别提高了14%、17%和14%。

Preparation and characterization of carbon fiber-graphene oxide/epoxy composites

Five graphene oxide (GO) with different oxidation degrees were prepared by the modified Hummers method. The composition and structure evolution of prepared GO were studied by elemental analysis, X-ray photo-electron spectroscopy and FTIR spectroscopy. The disperse states of different GO in the epoxy hardener (isophorone diamine, IPDA) were observed by an optical microscope. The GO sample which showed the best dispersibility was used to modify carbon fiber/epoxy(CF/EP) composites. The results indicate that by increasing the quantity of oxidant and reaction time, the oxidation degrees of GO increase accordingly. At a low oxidation degree, the functional groups on GO surfaces mainly contain carboxyl, carbonyl and phenolic groups. As the oxidation degree increases, the ether, epoxy and aliphatic hydroxyl groups gradually become dominant on GO surfaces. The disperse state of GO in IPDA is closely associated with the oxidation degree of GO. Both GO with the low and high oxidation degrees show clear aggregation. In addition, the GO surfaces can be chemically functionalized by IPDA during the dispersing process. Compared with the control sample with the unmodified EP matrix, the CF-GO/EP composites show about 14%, 17% and 14% increases in flexural strength, interlaminar shear strength and mode Ⅱ critical strain energy release rate (G_ⅡC), respectively, when the GO(0.2wt%) is added which has the best dispersibility is incorporated in the EP matrix.