Coarse-grained molecular dynamics simulation of deformation and fracture in polycarbonate: Effect of molar mass and entanglement

Abstract

Polycarbonate is a promising candidate material for applications as structural element owing to its prominent properties including lightness, strength and toughness. To sustain complex mechanical loadings and resist fracture, it is essential to obtain reliable constitutive relations of deformation. Such constitutive laws that are used for the design and optimization of polymer-based engineering products can be directly obtained from computer simulations. In this study we performed coarse-grained molecular dynamics (CGMD) simulations of polycarbonate to gain a better understanding of the deformation and fracture mechanisms at the molecular level and to clarify its dependency on the molecular structure. In particular, we investigated how the state of entanglement influences the deformation behavior for simulation models with various molar masses. We found a significant effect of the molar mass on the stress-strain curves; i.e. the larger the molar mass is, the larger stress can be reached after yielding, suggesting that molar mass plays a major role in the brittle-ductile transition of polycarbonate.