The effect of temperature on the viscoelastic response of rubbery polymers at finite strains

Constitutive equations are derived for the viscoelastic response of rubbery polymers at finite strains. A polymer is thought of as a network of long chains connected to temporary junctions. At a random time, a chain detaches from a junction, which is treated at transition from its active state to the dangling state. A dangling chain at a random time captures a new junction in the vicinity of its free end and returns to its active state. Breakage and reformation of long chains are modeled as thermo-mechanically activated processes. Stress–strain relations for a rubbery polymer are developed using the laws of thermodynamics. Adjustable parameters in the model are found by fitting observations in uniaxial tensile tests for a carbon black filled rubber at various temperatures. Fair agreement is demonstrated between experimental data and results of numerical simulation.