Evaluation of mechanical interlock effect on adhesion strength of polymer-metal interfaces using micro-patterned surface topography

This study concerns with the explanation of the wide range of adhesion strengths observed depending on the nature of substrate surface topography by linking macroscopic adhesion strength to microscopic energy-expenditure mechanisms during fracture. The dominant factors to which the adhesion strength of polymer-metal interfaces is attributed are investigated theoretically and experimentally. In an attempt to elucidate the effect of mechanical interlock on adhesion strength, micro-patterns were fabricated on metal surfaces as a designed surface topography. It was found that the molecular dissipation of the polymer in the vicinity of the interface is the major cause of the practical energy of separation. Furthermore, it is shown that loading mode controls the mechanical interlock effect, which is attributed to the fact that the stress distribution at the interface controls the deformation and failure characteristics of the polymer resin near the interface. Therefore, mechanical interlock promoted by adsorption provokes energy dissipation processes during fracture, which practically constitute the adhesion strength of a polymer-metal interface. The contribution of mechanical interlock to adhesion strength is systematically assessed by varying micro-pattern dimensions. The influence of the work of adhesion, cohesion and other dissipation energy on adhesion strength is examined by measuring each contribution to the total work of fracture. (C) 2010 Elsevier Ltd. All rights reserved.