Coarse-Grained Molecular Dynamics Simulation of Fracture in Polycarbonate: Fracture Stress Prediction from Molecular Entanglement and Spatial Distribution

Abstract

Polycarbonate finds a wide range of applications as structural materials due to the prominent mechanical and physical properties. It is urged to clarify the molecular origin of its mechanical properties for better designing the molecular structure. In this study, we investigated the effect of entanglement and spatial distribution of molecules in the initial structure on fracture stress by means of coarse-grained molecular dynamics (CGMD) simulation. By altering the method of creation of initial molecular structures, we successfully obtained wide variations of the number of entanglements (N_e) and the radius of gyration (R_g). Using the obtained structures as the initial configuration, we performed uniaxial tension simulations to evaluate the maximum stress (σ_max) after yielding. We found that σ_max cannot be described by either N_e or R_g alone but is expressed as a function of both of them (σ_max = f(N_e,R_g)).