Etching of diamond-like carbon films deposited on polyethylene terephthalate

Abstract

Recently, the diamond-like carbon (DLC) films are deposited in the wall of the polyethylene terephthalate (PET) bottles because of the protection for carbon dioxide gas penetration and deterioration against ultraviolet irradiation. However the DLC films fall into the contamination through the recycling process of PET bottle. In order to recycle the PET bottles deposited in DLC films, it is quite necessary to remove the DLC films at the early stage of recycling process. The DLC films were chemically etched by the glow discharge plasma of oxygen gas because carbon films were greatly reacted by the oxygen radicals and ions in the plasma. The etching of the DLC films deposited on the PET materials has been investigated using Raman spectroscopy. The complete removal of the DLC films was confirmed by Raman spectra. The etching depth increases with the etching time and the etching rate at optimum condition is approximately 50 nm/min. Atomic force microscopy observation was relieved surface condition of the PET after the etching treatment at different etching time. The surface roughness of the PET completely removed DLC films is almost same as the pure PET substrate without the exposure of oxygen plasma.