Surface modification of poly(ethylene terephthalate) (PET) by magnet enhanced dielectric barrier discharge air plasma

In order to study the effect of magnet enhanced plasma on polymer surface, a dielectric barrier discharge (DBD) setup with and without magnet is presented and used to modify poly(ethylene terephthalate) (PET) films at atmospheric pressure in ambient air. Surface analysis and characterization of the air plasma-treated PET films are performed using contact angle measurements, surface free energy, Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). The results show that air plasma leads to an obvious decrease in contact angle and increase in surface free energy. And surface wettability of the PET films treated by DBD with magnet is better than that without magnet. AFM images show an increase in surface roughness due to plasma etching. It is shown that O and N elements are introduced onto PET film surfaces as oxygen- and nitrogen-containing functional groups. The oxygen-containing groups can be identified as CO, CO and OCO. Their concentrations of the PET films treated with magnet are more than those treated without magnet. The difference is attributed to more active particles generated in DBD with magnet. Therefore, magnet field plays an important role in improving surface wettability of polymers.