Abstract
The crosslink density plays a key role in the mechanical response of the amorphous polymers in previous experiments. However, the mechanism of the influence is still not clear. In this paper, the influence of crosslink density on the failure behavior under tension and shear in amorphous polymers is systematically studied using molecular dynamics simulations. The present results indicate that the ultimate stresses and the broken ratios (the broken bond number to all polymer chain number ratios) increase, as well as the ultimate strains decrease with increasing crosslink density. The strain concentration is clearer with the increase of crosslink density. In other words, a higher crosslink density leads to a higher strain concentration. Hence, the higher strain concentration further reduces the fracture strain. This study implies that the mechanical properties of amorphous polymers can be dominated for different applications by altering the molecular architecture.
Highlights
Linear polymers are the most fundamental polymer molecular shapes and were extensively studied in view of their significant chemical and physical properties [1,2,3]
It should be noted that one can only obtain the qualitative mechanical properties of the crosslinked polymers using molecular dynamics (MD) simulation based on the finitely-extendable nonlinear elastic (FENE) potential, while the mechanism of the crosslink density effect on the mechanical properties can be effectively revealed since the parameters of the FENE potential are much less than those of the full-atom MD potentials
We studied the influence of crosslink density on the tensile and shear failure behavior in amorphous polymers using MD simulations
Summary
Linear polymers are the most fundamental polymer molecular shapes and were extensively studied in view of their significant chemical and physical properties [1,2,3]. Robbins’s group [15,16] studied the mechanical behavior of glassy polymers using coarse-grained (CG) modeling of polymer networks, in which the bead includes the lumped mass Both experimental and UA MD results have shown that the crosslink has a great effect on the compressive response of polymer particles [17,18]. The tensile failure behavior of the cross-linked polymers at large deformation is still not clear from a molecular perspective in view of the limitations of above UA and CG potentials. The MD simulations can be performed to effectively control the testing conditions and obtain the microscopic features of polymers, which can possibly be used to design different macroscopic properties by changing the molecular architecture of polymers. This study indicates that the mechanical properties of amorphous polymers can be dominated for different applications by changing the molecular architecture
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