From Waste to Worth: Glycerol-Driven Transformation of PET into Functional Polymers

Abstract

Polyethylene terephthalate (PET) is one of the most widely used polymers worldwide, particularly in packaging; however, its poor recyclability greatly contributes to plastic pollution. This study investigates an alternative valorization pathway through partial depolymerization with glycerol under both microwave and conventional heating conditions, without the use of catalysts or solvents. Both methods produced white, brittle solids with distinct physicochemical properties. Thermal analysis revealed an initial mass loss (130-220 °C) due to residual glycerol, followed by degradation steps indicative of shorter polymer chains. Additionally, the lower glass transition and melting points, along with sharper crystallization peaks, support the idea of chain scission and improved nucleation. Spectroscopic analyses identified new polyester structures derived from glycerol and PET, coexisting with unmodified PET. The modified material demonstrated promising results for Rhodamine-B adsorption, with high retention (> 97%) over multiple filtration cycles. This environmentally friendly, scalable approach effectively converts PET waste into functional materials, supporting the principles of green chemistry and the circular economy.

Keywords:
PET modification; glycerol; chemical recycling; circular economy; microwave irradiation; conventional heating