CHARACTERIZATION OF GRAFTED POLYETHYLENE BY CONTACT-ANGLE HYSTERESIS AND ESCA STUDIES

Low-density polyethylene (LDPE) has been functionalized in the bulk th rough dicumyl peroxide (DCP)-initiated grafting of dibutyl maleate (DB M) and vinyltrimethoxysilane (VTMO) in the temperature range from 140 to 200-degrees-C. The functionalized surfaces have been characterized through contact angle and contact-angle hysteresis measurements as wel l as through ESCA studies. The degree of grafting has been determined by infrared spectrophotometry. From the ESCA patterns of the modified polymers, the atomic ratios of oxygen to carbon and silicon to carbon have been calculated. Determination of an empirical relation between c ontact-angle hysteresis and the oxygen-carbon ratio of the functionali zed polymer surfaces has been attempted. It is found that the higher t he oxygen-carbon ratio, the lower the contact-angle value for polyethy lene. Contact angle-hysteresis increases with increase of the degree o f grafting. The total surface energy increases with grafting. The surf ace energy of the silane-grafted polyethylene (PEgS) is found to be lo wer than that of dibutyl maleate-grafted polyethylene (PEgDBM).