Studies on adhesion of polyethylene. Part I. Influence of functionality and phase transfer catalyst

Abstract

Low-density polyethylene (LDPE) has been oxidized using phase transferred permanganate as an oxidant. The resulting surface modifications have been characterized by different methods and the consequent adhesion promotion has been characterized in terms of contact angle and peel strength measurements. From contact angle measurements using water and formamide liquid drops, reversible work of adhesion, and thence γp s and γ-d s, the contributions of polar and dispersion components, respectively, have been calculated. The polar contributions increased in each oxidized LDPE relative to untreated LDPE and the surface energies also increased appreciably. The adhesion strengths between aluminium and untreated LDPE, as well as those between aluminium and oxidized LDPEs, have been examined by peel strength measurements. We found that the adhesion strength increased about 8-28 times in the case of oxidized LDPEs. Maximum strength was observed when benzyl triphenyl phosphonium permanganate was the oxidant. Both the p...