Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, People's Republic of China.
Soft Matter. 2017 Nov 22;13(45):8597-8608. doi: 10.1039/c7sm01794d.
This paper deals with molecular-dynamics simulations of the mechanical properties of prestretched double network filled elastomers. To this end, we firstly validated the accuracy of this method, and affirmed that the produced stress-strain characteristics were qualitatively consistent with Lesser's experimental results on the prestretched tri-block copolymers with a competitive double network. Secondly, we investigated the effect of the crosslinking network ratio on the mechanical properties of the prestretched double network homopolymers under uniaxial tension. We found that the prestretched double network contributes greatly to the enhanced tensile stress and ultimate strength at fracture, as well as to the lower permanent set (the residual strain) and dynamic hysteresis loss, both parallel and perpendicular to the prestretching direction. Notably, though, an anisotropic behavior was observed: in the parallel direction, both the first and the second crosslinked networks bore the external force; whereas in the perpendicular direction, only the second crosslinked network was relevantly effective. Finally, the polymer nanocomposites with a prestretched double network exhibited tensile mechanical properties similar to those of the studied homopolymers with prestretched double networks. Summing up the results, it can be concluded that the incorporation of prestretched double networks with a specified crosslinking network ratio seems to be a promising method for manipulating the mechanical properties of elastomers and their nanocomposites, as well as for introducing anisotropy in their mechanical response.
本文研究了预拉伸双网络填充弹性体的力学性能的分子动力学模拟。为此，我们首先验证了该方法的准确性，并确认所产生的应力-应变特性与 Lesser 在具有竞争双网络的预拉伸三嵌段共聚物上的实验结果定性一致。其次，我们研究了交联网络比在单轴拉伸下对预拉伸双网络均聚物的力学性能的影响。我们发现，预拉伸双网络对增强拉伸应力和断裂时的极限强度、较低的永久变形（残余应变）和动态滞后损耗都有很大的贡献，无论是平行于还是垂直于预拉伸方向。值得注意的是，观察到各向异性行为：在平行方向上，第一个和第二个交联网络都承受外力；而在垂直方向上，只有第二个交联网络具有显著的效果。最后，具有预拉伸双网络的聚合物纳米复合材料表现出与具有预拉伸双网络的研究均聚物相似的拉伸力学性能。综上所述，可以得出结论，加入具有特定交联网络比的预拉伸双网络似乎是一种很有前途的方法，可以控制弹性体及其纳米复合材料的力学性能，并在其力学响应中引入各向异性。
