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 interface s were measured by using the sessile drop method in order to calculate the work of adhesion. Polymers included linear low-density as well hi gh-density polyethylenes, while wall substrates included clean stainle ss steel and modified stainless steel by applying two different fluoro polymers 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 agre ement with earlier publications of Hill et al. (1991) and Hatzikiriako s et al. (1993). In the present work, the experimental results are int erpreted in terms of parameters defined by these two theories. It is s uggested that small deviations from the no-slip boundary condition in the case of polymer melt flow are due to a stress-induced chain detach ment/desorption of polymer chains from the wall. (C) 1998 The Society of Rheology.