Effect of storage condition and aging on acrylic acid inverse emulsion surface-grafting polymerization of PET films initiated by atmospheric pressure plasmas

Surface-grafting polymerization of acrylic acid inverse emulsion on PET films is carried out using atmospheric pressure plasma jet (APPJ) preirradiation technique to improve their hydrophilicity. The effects of plasma treatment duration and the conditions of post-plasma-treatment storage of preirradiated films prior to grafting were studied. In general, an increased treatment time results in an increase in grafting ratio. A higher storage environmental relative humidity or a high storage temperature leads to faster free radical decay, reducing the graft efficiency. SEM results show an almost continuous grafted layer on the film surface when graft ratio reached 1.05%, and the corresponding water contact angle reaches 5o. Hydrophobic recovery occurs for samples with a graft ratio of 0.12% owing to the surface reconstruction, while at higher graft ratios, the contact angle remains almost unchanged over one monthʹs aging.