Surface Properties and Morphology of PET Treated by Plasma Immersion Ion Implantation for Food Packaging

In this work, surface properties of PET (Polyethylene Terephthalate) modified by Plasma Immersion (PI), and Plasma Immersion Ion Implantation (PIII) were studied. Nitrogen and sulfur hexafluoride plasmas were used in a vacuum system coupled to a radiofrequency (rf) generator (13.56 MHz). Infrared spectroscopy (ATR-FTIR) detected the presence of new molecular groups on the PET surface after the treatment. Measurements of the contact angle, Ɵ, revealed a strong dependence of the surface wettability on the plasma parameters, control of which allows the production of hydrophilic or hydrophobic surfaces. The ion fluence was modelled as function of the penetration depth using suitable software (SRIM 2008) and is useful to understand the damage caused by ion implantation of the PET (ρ = 1.39 g/cm3). The optical transmittance of the treated material in the visible region, T (λ), depends on the gas used and the electrical configuration of the plasma. Water-vapor transmission rate (WVTR) revealed an increase in the barrier properties of the treated PET. PIII technique and N2 bombardment are more appropriate than plasma immersion and SF6 bombardment to increase T(λ) of PET in the visible region.