Improving the surface properties of cellophane by air plasma treatment

Air plasma treatment at low pressure was applied to modify the surface of a cellulose film with the aim to improve its wettability, dyeability and adhesion properties. The contact angles of different polar liquids on the treated films show an exponential decay with treatment time at a given power; the power–time reciprocity is followed. The calculated surface tension values exponentially rise to the same maximum value with a decrease of the polar fraction. ATR-FTIR analyses suggest that a cellulose dehydration takes place rather than a surface oxidation. The plasma treatment improves also the cellophane dyeability with typical dyes for cellulose fibers: the results of dye uptake follow the same trend as the surface energy. The bond strength of lap joints of cellophane with LLDPE film shows a strong improvement of the adhesion depending on the duration and the power of treatment. The whole results are consistent with ablation effects like those observed with air corona treatment rather than oxygen plasma.