Surface modification of polyethyleneterephthalate by an atmospheric-pressure plasma source

The modification of polyethyleneterephthalate (PET) surface by an atmospheric-pressure plasma source was investigated. The plasma was generated by a RF discharge at atmospheric pressure using a gas mixture of helium and oxygen. PET strips were exposed to plasma for different durations at the exit of the plasma source. Water contact angles were measured for surfaces modified with different RF powers, oxygen concentrations and exposure durations. The changes of the contact angles of the modified surfaces were monitored as a function of time. The surface modification was determined to be mainly a photochemical and chemical process through the analysis and experiments on ions, ultraviolet photons, oxygen atoms and ozone molecules.