Molecular dynamics simulation of fracture mechanism in the double interpenetrated cross-linked polymer
HX Li and HY Wu and B Li and YY Gao and XY Zhao and LQ Zhang, POLYMER, 199, 122571 (2020).
It is very crucial to understand the fracture mechanism of the double interpenetrated cross-linked polymer on the molecular level which consists with a flexible network and a stiff network. In this work, we investigated the effect of the network structure on their fracture behavior via a coarse-grained molecular dynamics simulation. The fracture energy first increases and then decreases with increasing the ratio of the stiff network or the cross-link density of each network. However, it shows a first quick and then slow increase with increasing the stiffness of the stiff network. The bond orientation degree is first calculated with the strain which can reflect the elongation. By characterizing the number of broken bonds and the rate of bond scission, more bond scission happens on the stiff network than on the flexible network. Meanwhile, the strain at the beginning of bond scission on the stiff network is less than that on the flexible network. Then by quantifying the stress contribution, the stiff network is found to bear more stress than the flexible one by analyzing the average stress borne by one bead which can be clearly observed by the contour plot of the atomic stress distribution. Furthermore, the number of voids first increases, then decreases and last rises with increasing the ratio of the stiff network. However, it shows a continuous increase with the cross-link density of each network or the stiffness of the stiff network. This is closely related to the rate of bond scission where the new voids are formed. In summary, this work could provide a new understanding how the network structure affects the fracture property of the double interpenetrated cross-linked polymer.
Return to Publications page