On the Expression of the Stress Tensor in Entangled Polymers from Molecular Models

To understand the flow behaviour of polymeric liquids, it is important to analyse the microscopic origin of the stress. The classical molecular theories relate the stress to the tensile force of entropic origin acting along the chains. The momentum transfer due to collisions between different molecules is not explicitly considered. Though certainly adequate for dilute solutions, that assumption becomes questionable in concentrated solutions and melts