Chemical Bond Scission and Physical Slippage in the Mullins Effect and Fatigue Behavior of Elastomers

Abstract

Understanding the molecular mechanism of mechanical response under a cyclic loading is of fundamental importance in designing high-performance elastomers with a long service life. Herein, we investigated the mechanical response and accompanying microstructural evolution of elastomers under a long-term cyclic loading by using coarse-grained molecular dynamics simulation. The typical characteristics of the Mullins effect are successfully reproduced to confirm the validation of our simulation. Through a systematical analysis for the evolution of an intrinsic structure for a pure elastomer, we find that the Mullins effect results from chain extension and chain slippage at a low cross-linking density, whereas at a high cross-linking density, it is mainly caused by bond rupture. Particularly, the optimized cross-linking density of a pure system can lead to optimum mechanical strength and fatigue resistance because of much greater energy dissipation by polymer chains with high mobility. The filled elastomer indi...