Ding Qiuyue, Ding Ning, Chen Xiangfeng, Guo Wenyue, Zaïri Fahmi
Engineering Research Center of Failure Analysis and Safety Assessment, Shandong Analysis and Test Center, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250014, China.
School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China.
Polymers (Basel). 2023 Jul 28;15(15):3218. doi: 10.3390/polym15153218.
This work presents a molecular dynamics (MD) simulation study on the effect of grain boundaries (GBs) on the mechanical properties of epoxy/graphene composites. Ten types of GB models were constructed and comparisons were made for epoxy/graphene composites containing graphene with GBs. The results showed that the tensile and compressive behaviors, the glass transition temperature (), and the configurations of epoxy/graphene composites were significantly affected by GBs. The tensile yield strength of epoxy/graphene composites could be either enhanced or weakened by GBs under a tensile load parallel to the graphene sheet. The underlying mechanisms may be attributed to multi-factor coupling, including the tensile strength of the reinforcements, the interfacial interaction energy, and the inflection degree of reinforcements. A balance exists among these effect factors, resulting in the diversity in the tensile yield strength of epoxy/graphene composites. The compressive yield strength for epoxy/graphene composites is higher than their counterpart in tension. The tensile/compressive yield strength for the same configuration presents diversity in different directions. Both an excellent interfacial interaction and the appropriate inflection degree of wrinkles for GB configurations restrict the translational and rotational movements of epoxy chains during volume expansion, which eventually improves the overall . Understanding the reinforcing mechanism for graphene with GBs from the atomistic level provides new physical insights to material design for epoxy-based composites containing defective reinforcements.
本文通过分子动力学（MD）模拟研究了晶界（GBs）对环氧/石墨烯复合材料力学性能的影响。构建了十种类型的晶界模型，并对含晶界石墨烯的环氧/石墨烯复合材料进行了比较。结果表明，晶界对环氧/石墨烯复合材料的拉伸和压缩行为、玻璃化转变温度（）以及结构有显著影响。在平行于石墨烯片的拉伸载荷下，晶界可增强或削弱环氧/石墨烯复合材料的拉伸屈服强度。其潜在机制可能归因于多因素耦合，包括增强材料的拉伸强度、界面相互作用能以及增强材料的弯曲程度。这些影响因素之间存在平衡，导致环氧/石墨烯复合材料的拉伸屈服强度具有多样性。环氧/石墨烯复合材料的压缩屈服强度高于其拉伸屈服强度。相同结构的拉伸/压缩屈服强度在不同方向上具有多样性。良好的界面相互作用和晶界结构中适当的皱纹弯曲程度都限制了环氧链在体积膨胀过程中的平移和旋转运动，最终提高了整体的。从原子层面理解含晶界石墨烯的增强机制，为含缺陷增强材料的环氧基复合材料的材料设计提供了新的物理见解。
