Effects of solvent exposure on the adhesion of grafted PE to EVOH copolymer

Multilayer polymers are gaining popularity in many industrial applications, where the combination of various advantages of the individual materials may be exploited (e.g. mechanical strength and chemical resistance). Such materials rely heavily on the quality of interfacial adhesion and this in turn may alter with solvent exposure. Here, we study the ageing of a multilayer high density polyethylene, grafted polyethylene (PEg), ethylene/vinyl alcohol copolymer (EVOH) assembly in organic solvents, and its effect on the T-peel resistance of the EVOH/PEg interface (interphase). Apolar solvents absorb essentially in the polyethylenic materials leading to reduced peel strength due to modification of polymer bulk properties, rather than to changes in intrinsic adhesion strength. Ethanol diffuses readily into the EVOH leading to an intrinsic drop in energy of adhesion. In the cases studied, reduction of interfacial, peel strength was found to be largely reversible on drying the polymer assembly.