Chemical structures of surface‐oxidized and grafted polyethylene: Adsorption and wetting studies

Surfaces of thin low‐density polyethylene films are chemically modified either by oxidation or by grafting with maleic acid. The oxidation is performed at constant tempera‐ture by sulfuric acid and potassium chlorate mixtures of variable compositions. Grafting was carried out at constant temperature and time in the solution of maleic anhydride in acetic anhydride in the presence of benzoyl peroxide initiator. Isotherms of calcium adsorption at these surfaces have been established by the use of the radioactive tracer technique. The chemical composition (number of obtained polar sites) of these modified polyethylene surfaces is thus determined. The measurements were conducted at different pH and salt concentrations. Wettability of the modified surfaces is determined by contact angle measurements. It was found that the wettability of these films is directly related to the chemical composition of their surfaces.