Effect of UV/ozone treatment on the wettability and adhesion of polymeric systems

Abstract

The impact of UV/ozone treatment on the wettability and adhesion of ethylene propylene diene methylene (EPDM) rubber, polyvinyl chloride (PVC), and acrylonitrile butadiene styrene (ABS) was investigated using contact angle measurements, OWRK surface free energy model, standardized adhesion tests, and spectroscopic and microscopic observations. It is found that UV/ozone treatment enhances the wettability of the examined polymers. Also, it considerably improved the adhesion strength of PVC and ABS samples, and shifted their failure modes from adhesive to cohesive. FTIR-ATR characterization showed insignificant changes in the chemical structures of the studied materials. However, SEM observation showed newly-created wrinkles and micro-holes on treated PVC surfaces, and micropores on ABS surfaces. These UV-induced morphological changes on PVC and ABS surfaces increased the surface area which can promote the mechanical interlocking with the adhesive. This explains the improvement of their adhesion strength. Implications of the current study for the processing of strongly bonded polymeric joints are discussed.