On the mechanism of the flow of polymers

A non-Newtonian flow of a polymer melt is discussed. The description of the exponential decrease of the apparent viscosity by the well-known Eyring formula with an activation energy reduction proportional to the shear stress does not take into account specific features of the polymeric structure. We propose to modify the description of the macromolecular flow mechanism by including conformational changes of the polymeric chains. The elasticity of a strained polymeric chain, having an entropy origin, can be the reason of the reduction of the activation energy for the transition of a molecular-kinetic unit of the chain into a new equilibrium state in the flow direction during the thermal fluctuation. In that case, the activation energy of the transition should decrease by a value proportional to the reversible high-elastic component of the shear deformation caused by the flow of the polymer.