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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、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。在环氧树脂基体中加入分散效果最佳的GO(0.2 wt%)后,与碳纤维/环氧树脂复合材料相比,GO-碳纤维/环氧树脂复合材料的弯曲强度、层间剪切强度、Ⅱ型层间断裂韧性分别提高了14%、17%和12%。
Five kinds of graphene oxide (GO) with different oxidation degree were prepared by a modified Hummers method. The composition and structure evolution of GO were characterized by elemental analysis, X-ray photoelectron spectroscopy and FTIR infrared spectroscopy. The optical microscope was used to observe the dispersion of different GO in isophorone diamine (IPDA), and the best dispersion GO sample was used to modify carbon fiber / epoxy composites. The results showed that with the increase of oxidant dosage and reaction time, the oxidation degree of GO also increased. In the low degree of oxidation, GO surface functional groups mainly carbonyl, carboxyl, phenolic hydroxyl-based. With the continuous increase of the degree of oxidation, GO surface functional groups mainly ether, epoxy and alcoholic hydroxyl structure. The dispersion state of GO in IPDA is closely related to the degree of oxidation, and the lowest and highest degree of oxidation of GO shows significant aggregation. In addition, the GO surface can be chemically modified by IPDA during dispersion. Compared with the carbon fiber / epoxy resin composites, the GO-carbon fiber / epoxy resin composites have better flexural strength, interlaminar shear strength, Type Ⅱ interlaminar fracture toughness increased by 14%, 17% and 12% respectively.