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

Abstract

In this work, it was used a vacuum system on a set up well exploited, in order to use Plasma Immersion Ion Implantation (PIII) and Plasma Immersion (PI cathode or PI anode), which were suitable techniques for the surface treatment over the Polyethylene Terephthalate (PET) substrates, from Coke bottles of 2 L TM. The purpose was: to change their wettability, surface morphology and optical transmittance at visible light. Some papers regard the physic-chemical alterations on the surface of PET samples. However, the selectivity of those plasma treatments, results in a notable and partial combination of surface properties, even with serious restrictions. It's reasonable to reveal the results founded here, using nitrogen and fluorine plasmas, since exposing the sample holder at the room temperature during the treatment time of 900 s. The Origin software 8.0 fitted the graphs that show: The evolution of surface wettability behavior depends on the plasma technique applied and the gas employed to them. In some cases, the surface hydrophilization was not stable as seen by the temporal evolution of the contact angles measurements, Ɵ (t). By the AFM images, it is possible to view a mild modification of the PET surface immersed in the plasma, whereas: roughness Rz, increased only a few tens of nanometers, in relation to the virgin PET (1.8 nm), even in a strong ion bombardment during the treatment. As a general trend, the roughness increases slightly for all techniques. Finally, gain or loss of optical transmission, T (λ), at visible radiation, depends on the parameters of the plasma treatment. PIII technique and N 2 bombardment are more indicated than the plasma immersion and SF 6 bombardment to increase the transmittance of PET at visible region. In general, those parameters selected imply in a positive plasma conditions, considering the overview to try out a technological destination for recycled commercial polymers.