Li Xueliang, Zhang Xiaoyu, Chen Jianzhong, Huang Li, Lv Yong
School of Science, Wuhan University of Technology, Wuhan 430070, China.
Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics, Wuhan University of Technology, Wuhan 430070, China.
Polymers (Basel). 2021 Jan 14;13(2):261. doi: 10.3390/polym13020261.
Based on the all-atomic molecular dynamics simulation method, the tensile creep behavior of epoxy-based polymer was discussed. The physical and mechanical properties of the model were characterized, such as glass transition temperature and yield strength. The simulation results are very close to the previous simulation and experimental results, and the correctness of the model is verified. On this basis, the tensile creep behavior and free volume evolution of polymer epoxy resin at different temperatures and stress levels were studied. The model fully predicted the three classical stages of epoxy resin creep (the primary, secondary and tertiary) and the dependent behavior of epoxy resin creep on temperature and stress level at the molecular level, and the creep rate increases with the increase of temperature and stress level. It was found that with the progress of the creep process, the proportion of free volume increases gradually under high stress levels, indicating that the effect of creep behavior on the structure of epoxy resin is that the interaction between atoms becomes weaker and weaker by increasing the distance between atoms, which finally induces creep failure in the material.
基于全原子分子动力学模拟方法，讨论了环氧基聚合物的拉伸蠕变行为。对模型的物理和力学性能进行了表征，如玻璃化转变温度和屈服强度。模拟结果与先前的模拟和实验结果非常接近，验证了模型的正确性。在此基础上，研究了不同温度和应力水平下聚合物环氧树脂的拉伸蠕变行为和自由体积演化。该模型在分子水平上充分预测了环氧树脂蠕变的三个经典阶段（初级、次级和三级）以及环氧树脂蠕变对温度和应力水平的依赖行为，且蠕变速率随温度和应力水平的升高而增加。研究发现，随着蠕变过程的进行，在高应力水平下自由体积的比例逐渐增加，这表明蠕变行为对环氧树脂结构的影响是通过增加原子间距离使原子间相互作用越来越弱，最终导致材料发生蠕变失效。
