This study presents the atomistic characterization of the fiber/matrix interfacial properties in the hybrid functionalized carbon fiber reinforced polymer composites. A molecular model is developed containing ZnO nanowire (NW) aligned vertically on functionalized graphene sheet (FGS) and embedded in the cross-linked epoxy matrix. The molecular dynamics simulation technique is employed to evaluate the traction-separation behavior of FGS in both opening and sliding modes. Three different chemical groups of carboxyl (COOH), carbonyl, and hydroxyl with multiple grafting densities are explored as functional groups. The results reveal that the interfacial strength and the cohesive energy are considerably enhanced in the functionalized model compared with the pristine structure. COOH has the most impact on the traction-separation response with a 112% improvement of interfacial strength. The enhanced effect of functionalization is more intense in the shear separation than the normal one. However, comparing the graphene/ZnO NW with graphene/no ZnO NW structures show that adding ZnO NW can compensate for the slight effect of grafting in the normal direction. The results indicate that combining the growth of ZnO NW and functionalization enhances the interfacial strength up to two-fold in the opening and up to eight-fold in the sliding mode of carbon fiber composites.

中文翻译：

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石墨烯和 ZnO NW/环氧树脂之间界面性质的功能化增强：分子动力学模拟研究

本研究介绍了混合功能化碳纤维增强聚合物复合材料中纤维/基体界面特性的原子表征。开发了一种分子模型，其中包含在功能化石墨烯片 (FGS) 上垂直排列并嵌入交联环氧树脂基质中的 ZnO 纳米线 (NW)。采用分子动力学模拟技术来评估 FGS 在开模和滑模下的牵引分离行为。探索了具有多种接枝密度的羧基 (COOH)、羰基和羟基这三种不同的化学基团作为官能团。结果表明，与原始结构相比，功能化模型中的界面强度和内聚能显着增强。COOH 对牵引分离响应的影响最大，界面强度提高了 112%。功能化的增强作用在剪切分离中比正常的更强烈。然而，将石墨烯/ZnO NW 与石墨烯/无 ZnO NW 结构进行比较表明，添加 ZnO NW 可以补偿法线方向接枝的轻微影响。结果表明，结合ZnO NW的生长和功能化，碳纤维复合材料的开口强度提高了两倍，滑动模式提高了八倍。将石墨烯/ZnO NW 与石墨烯/无 ZnO NW 结构进行比较表明，添加 ZnO NW 可以补偿法线方向接枝的轻微影响。结果表明，结合ZnO NW的生长和功能化，碳纤维复合材料的开口强度提高了两倍，滑动模式提高了八倍。将石墨烯/ZnO NW 与石墨烯/无 ZnO NW 结构进行比较表明，添加 ZnO NW 可以补偿法线方向接枝的轻微影响。结果表明，结合ZnO NW的生长和功能化，碳纤维复合材料的开口强度提高了两倍，滑动模式提高了八倍。