Effects of molding surfaces on the wettability of compression-molded polypropene films

Contact angles were measured for a series of compression-molded polypropene films blended with acrylic acid (AA) or maleic anhydride (MAH)/polyethylen e oxide (PEO) (1: 1) additives. The influence of different molding conditio ns concerning time and temperature as well as a coating of the aluminium fo ils used for the processing with polyethylene oxide (PEO) or polyvinyl pyrr olidone (PVP) were investigated. Films processed with uncoated aluminium fo ils showed, with one exception, no influence on contact angles with increas ing molding temperatures and longer processing times. Upon coating the alum inium foils with hydrophilic substances the receding contact angles decreas e by up to 60 degrees with constant contact angle hysteresis. This behaviou r corresponding to a permanent hydrophilization is attributed to chemical r eactions of the coating with the functional groups of the additives.