The work of adhesion of polymer/wall interfaces and its association with the onset of wall slip

The interfacial characteristics of a variety of polymer/wall interfaces were measured by using the sessile drop method in order to calculate the work of adhesion. Polymers included linear low-density as well high-density polyethylenes, while wall substrates included clean stainless steel and modified stainless steel by applying two different fluoropolymers in order to alter its surface energy. A linear correlation is found between the critical shear stress for the onset of slip and the work of adhesion of the corresponding polymer/wall interface, in agreement with earlier publications of Hill et al. (1991) and Hatzikiriakos et al. (1993). In the present work, the experimental results are interpreted in terms of parameters defined by these two theories. It is suggested that small deviations from the no-slip boundary condition in the case of polymer melt flow are due to a stress-induced chain detachment/desorption of polymer chains from the wall. (C) 1998 The Society of Rheology.