Roles of repeating-unit interactions in the stress relaxation process of bulk amorphous polymers

ABSTRACT How the repeating-unit chemistry dominates polymer viscoelasticity remains as unclear. We employed four-set interaction parameters to represent thermodynamic and kinetic aspects of local intrachain and interchain interactions between monomers, which characterize polymer repeating-unit chemistry. We performed kinetic Monte Carlo simulations of Debye stress relaxation in stretched and parallel-aligned bulk amorphous polymers and evaluated the relative importance of each interactions in the diffusion energy derived from their Arrhenius fluid behaviors. The results demonstrated that, under the same strengths, the kinetic aspects of intrachain and interchain interactions raise much higher diffusion energies than their thermodynamic aspects. We discussed the example case of polyethylene. Our work paves the way towards the prediction of the structure-property relationship of the mechanical properties in bulk amorphous polymers.