A MOLECULAR DYNAMICS STUDY ON THE STRAIN RATE DEPENDENCE FOR ELASTO-PLASTIC RESPONSE OF CROSSLINKED EPOXY

초록

In this study, elasto-plastic deformation mechanism on epoxy polymer was investigated considering effect of crosslink density with the aid of molecular dynamics simulations. From the equilibrated unit cells, uniaxial loading-unloading simulations were conducted to understand the origin of the plastic deformation. The vdW and dihedral angle energy are of the prime potential energy components inducing permanent deformations. To observe the microscopic structure of the unit cells, the change of the free volume and dihedral angles during the loading-unloading simulations were monitored rigorously. Consequently, the fundamental mechanism behind plastic deformations of epoxy systems are attributed to the permanent variations of free volume and dihedral angle after unloading. The benzene ring-related torsional types are of primary factors generating a permanent plastic deformation due to the inherent rigidity of benzene ring structure. The effect of crosslink density on the plastic deformation was further examined considering the strain rate dependency.

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