A Phase-Field Model for Structural Damage in Polytetrafluoroethylene (PTFE)

Deformation of polymers, due to their molecular structures, as well as their motion and relaxation mechanisms, are greatly influenced by temperature and mechanical load history. This work describes and simulates a structural phase-field model for polytetrafluorethylene (PTFE) polymer. The constitutive multimechanism model used considers an isothermal non-linear elastoviscoplastic model, which can represent both elastic molecular interactions and viscoplastic flow from polymer segments. The material parameters for these complex rheological models are determined through a genetic algorithm, which adjusts the curves obtained from simulated models to match the stress-strain experiments available in literature. The stress-strain curves, up to the point of rupture, are then compared with experimental results.