Yin Fei, Tang Chao, Li Xu, Wang Xiaobo
College of Engineering and Technology, Southwest University, Chongqing 400715, China.
School of Electronics and Computer Science, University of Southampton, SO171BJ Southampton, UK.
Polymers (Basel). 2017 Oct 22;9(10):537. doi: 10.3390/polym9100537.
Seven composite models of meta-aramid fibers with different moisture contents were studied using molecular dynamics simulation. The effects of moisture on the thermal stability and mechanical properties of the fibers and their mechanisms were analyzed, considering characteristics such as hydrogen bonding, free volume, mean square displacement, and mechanical parameters. The simulation results showed that the large number of hydrogen bonds between water molecules and meta-aramid fibers destroyed the original hydrogen-bond network. Hydrogen bonds between the molecular chains of meta-aramid fibers were first destroyed, and their number decreased with increasing moisture content. The free volume of the fibers thereby increased, the interactions between fiber chains weakened with increasing moisture content, and the fiber chain movement intensified accordingly. The ratio of diffusion coefficients of the water molecules to moisture contents of the composite models increased linearly, and the water molecule diffusion increased, which accelerated the rate of damage to the original hydrogen-bond network of the meta-aramid fibers and further reduced their thermal stability. In general, the mechanical properties of the composites were negatively related to their moisture content.
采用分子动力学模拟研究了七种不同含水量的间位芳纶纤维复合模型。考虑氢键、自由体积、均方位移和力学参数等特性，分析了水分对纤维热稳定性和力学性能的影响及其作用机制。模拟结果表明，水分子与间位芳纶纤维之间大量的氢键破坏了原有的氢键网络。间位芳纶纤维分子链间的氢键首先被破坏，且其数量随含水量的增加而减少。纤维的自由体积由此增大，纤维链间的相互作用随含水量的增加而减弱，纤维链的运动相应加剧。复合模型中水分子扩散系数与含水量之比呈线性增加，水分子扩散增强，加速了间位芳纶纤维原有氢键网络的破坏速率，进一步降低了其热稳定性。总体而言，复合材料的力学性能与其含水量呈负相关。
