A Slip Model for Linear Polymers Based on Adhesive Failure

Abstract

Abstract Eyring's theory of liquid viscosity was adapted to the special case of polymer molecules at a solid interface. The resulting model gives the slip velocity as a function of wall shear stress, temperature, pressure, work of adhesion and the molecular parameters of the polymer. The work of adhesion is related, on the one hand, to the critical stress for the onset of slip, and on the other, to the surface tension of the melt on the surface of interest. The predictions of the model are compared with previously published data for the slip of polyethylenes on steel and on steel treated with processing aids, and the agreement is very good. Unlike previous power-law slip models, the new model provides for a smooth transition from no-slip to slip flow at the critical stress.