Corona Discharge Treatment of Polyolefins

The effects of corona discharge treatment on polyethylene and polypropylene homopolymers have been studied. X-ray photoelectron spectroscopy was used to determine surface compositions which were related to surface free energy estimates from contact angle measurements. Changes in composition and surface free energy were measured as a function of treatment level. The work of adhesion was seen to increase with oxygen incorporation. The increase was not linear and this is attributed to an increase in the degree of sub-surface to near-surface oxidation at intense treatment levels. Aging of samples followed by XPS and contact angle measurement showed that surface wettability is reduced whereas a slight increase in surface oxygen was found. This phenomenon was attributed to the reorientation/migration of functional groups. Morphological examination by scanning electron microscopy indicated no surface roughening at any power level.