Discoloration of green PET bottles recycled with chemical agents by reactive extrusion

Abstract

This study evaluates the effect of incorporating chemical agents with green polyethylene terephthalate (PET) bottles on extrudate color change and other properties. First, the best type of chemical agent that decolorizes recycled green PET bottles (RGPB) with good processability was determined. RGPB-chemical agent mixtures were evaluated, reducing, photoinitiator, or oxidant, where the best one turned out to be the oxidizing agent, a dicumyl peroxide. Then new mixtures of RGPB-oxidizing agent, dicumyl or benzoyl, were made in a reactive extrusion process employing a drying hopper to avoid hydrolytic degradation. The intrinsic viscosity, crystallinity, and color change of extrudates were determined. It was determined by SEM with EDS that the dye is possibly a chlorinated copper phthalocyanine. The final results show an increase in the intrinsic viscosity of the PET handling dicumyl peroxide, a partial whitening of the extrudates, and an increase in the crystallinity of the PET, which contributed to a decrease the hue and saturation of the green color of RGPB. Where the dicumyl peroxide present in mixtures with RGPB interacts with chlorinated copper phthalocyanine to produce phthalamide or phthalic acid, which are white.