Abstract This study provides a comprehensive investigation on the effect of epoxy crosslinking density and number of graphene layers on the interfacial mechanical behavior of graphene/epoxy nanocomposites. In particular, the graphene layers are detached in the normal and sliding directions within the framework of steered molecular dynamics, and the traction-separation curves are extracted for the whole separation process. The damage mechanism is also studied by analyzing the evolution of the local number density during pull-out tests. For better results interpretation, the variation of the interaction and adhesion energies, the number of pulled-out epoxy chains, and the distribution of crosslinked and uncrosslinked species are also investigated and discussed. Based on the results obtained, the crosslinking density has a significant effect on the interfacial properties between graphene and epoxy, especially in the normal mode. The damage behavior is also determined as the function of the epoxy crosslinking density so that at low crosslinking densities, the damage occurs in the polymer near the graphene, while the failure takes place in the interphase for higher crosslinking degrees. Increasing the number of graphene layers leads to a weaker interfacial strength, except for the double-layered graphene systems which have the highest traction peak among all samples.

中文翻译：

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石墨烯纳米片/环氧树脂复合材料界面特性和损伤机制的原子模拟

摘要 本研究对环氧树脂交联密度和石墨烯层数对石墨烯/环氧树脂纳米复合材料界面力学行为的影响进行了全面调查。特别是，在分子动力学的框架内，石墨烯层在法向和滑动方向上分离，并提取了整个分离过程的牵引-分离曲线。还通过分析拉拔试验期间局部数密度的演变来研究损伤机制。为了更好地解释结果，还研究和讨论了相互作用和粘附能的变化、拉出的环氧链的数量以及交联和未交联物质的分布。根据获得的结果，交联密度对石墨烯和环氧树脂之间的界面性质有显着影响，尤其是在正常模式下。损伤行为也被确定为环氧交联密度的函数，因此在低交联密度下，损伤发生在石墨烯附近的聚合物中，而失效发生在交联度较高的界面中。增加石墨烯层数会导致界面强度变弱，除了双层石墨烯系统在所有样品中具有最高的牵引峰值。而失效发生在交联度较高的界面。增加石墨烯层数会导致界面强度变弱，除了双层石墨烯系统在所有样品中具有最高的牵引峰值。而失效发生在交联度较高的界面。增加石墨烯层数会导致界面强度变弱，除了双层石墨烯系统在所有样品中具有最高的牵引峰值。