Determination of a recyclability index for the PET glycolysis

The recycling of plastics by depolymerization brings environmental and energetic benefits. This work seeks to determine a recyclability index (RI) via comparative analysis considering costs and energy consumption in the chemical recycling of poly(ethylene terephthalate) (PET) by glycolysis with propylene glycol without catalysts, and in the production of unsaturated polyester (UP) with ortophthalic anhydride. The analysis was carried out combining theory and experimental data from an actual industrial operation plant. Mass balance, energy balance and economic analyses were carried out. The properties of the final UP resin obtained via both routes were comparable. The results indicate that the glycolysis of PET can be viable for an incorporation of up to 35% of recycled PET in the UP resin formulation.