Molecular dynamics simulation on the mechanical properties of natural-rubber-graft-rigid-polymer/rigid-polymer systems

A coarse-grained model-based molecular dynamics simulation was employed to investigate the mechanical properties of NR-graft-rigid-polymer/rigid-polymer systems (N30-g-(R3)6/R10). An external factor (the strain rate) as well as internal factors such as the nonbonding interaction strength, the proportion of rigid polymers, and architecture parameters (the length and number of graft chains in a molecule) were examined for their effect on the tensional behavior of N30-g-(R3)6/R10 systems. Simulation results show that a higher strain rate can promote the enhancement of mechanical performance, such as a higher modulus or yield stress. Moreover, the stress and modulus increase with an increase of the nonbonding interaction strength within rigid polymers or of the rigid polymer proportion in the systems. However, the increasing stress was found to reach a limit with a continuously increasing rigid polymer proportion. On increasing the number of graft chains in a molecule, the stress increases at small strains. However, at large strains, the evident increase in stress was found in systems in which a graft molecule has longer graft chains. In addition, our research shows that N30-g-(R3)6/R10 blends exhibit improved mechanical properties and better compatibilities relative to N30/R10, which is consistent with the experimental results. Lastly, comparisons with experimental observations were also made to ensure the rationality of the simulation results. Overall, bond stretching, bond orientation, and nonbonding interactions were found to be crucial in governing the mechanical properties of the N30-g-(R3)6/R10 systems. These findings may provide important information for further experimental and simulation studies of NR hybrid materials.