Evaluating the Effect of Photoaging on Polyethylene Permeability: Measurement of the Transport Properties in the Liquid Phase

The consequences of polyethylene photooxidation on the transmission rate of various permeants in methanolic solution were investigated using a self-designed setup with in-live fluorescence or UV detection. Polyethylene films were subjected to accelerated artificial photoaging, which caused the increase of their polarity owing to the generation of various polar functional groups, e.g., carbonyl and hydroxyl groups, homogeneously distributed within the sample thickness. For nonphotoaged polyethylene, the transmission rate was found to be higher for nonpolar permeants, owing to their higher solubility in a nonpolar polymer. However, after 200 h of photoaging, an important increase in the transmission rate was observed for polar permeants, with no change for nonpolar ones. This may be the consequence of the increase of the polarity of polyethylene during the photoaging process that permits the occurrence of permeant/polymer interactions resulting in an increase of the solubility at the polymer feed side.