Force-biased chemical degradation in rubbery networks: Insights from discrete network simulations

Abstract

This study investigates the effect of force-assisted chemical reaction leading to chain scission on the mechanical and swelling behaviour of rubbery networks. A Discrete Network (DN) modelling approach is adopted, in which polymer chains are represented as entropic springs connected at crosslink points. Force-accelerated chain scission is simulated using a Kinetic Monte Carlo algorithm. The model further accounts for degradation-induced swelling due to solvent uptake and mass loss due to the release of chain clusters detached from the main network. Discrete Network simulations highlight the role of force heterogeneities on the degradation of mechanical properties. Chains bearing the largest forces are cut preferentially, which accelerates the reduction in modulus and loss of percolation. When degradation occurs under constraint, force-biased degradation leads to anisotropic residual elastic properties. These effects cannot be captured by a state-of-the-art micromechanics-based continuum model, which does not account for the redistribution of forces through the network. Overall, the discrete network framework provides a promising platform to study a broader range of mechano-chemical phenomena in elastomers and gels.