Recycling of PVC tarpaulin reinforced with PET through glycolysis using betaine, a bio-based catalyst

초록

Polyvinyl chloride (PVC) tarpaulins reinforced with poly(ethylene terephthalate) (PET) fibers are widely used in various industrial applications. However, the increasing demand for recycling PVC tarpaulin waste poses challenges because of the difficulty in separating the two different plastics. In this study, we investigated the possibility of recycling PVC and PET through the glycolysis of PET. The milled PVC tarpaulin underwent a glycolysis process, selectively depolymerizing the PET fibers into water-soluble bis(2-hydroxyethyl) terephthalate (BHET), while the PVC was removed by filtration. The PET fibers were selectively depolymerized by 77.6% after reacting at 190 degrees C for 2 h in the presence of 0.5% (w/w) betaine as a catalyst, quantitatively yielding BHET. During glycolysis, the physical appearance of the PVC changed because of leaching of the plasticizer, however, no dechlorination or shortening of the PVC polymer was observed. Interestingly, additives in PVC, such as CaCO3 and CZ-stabilizer, act as catalysts for glycolysis, thereby enhancing PET depolymerization. The recovered PVC, when blended into a PVC formulation, maintained its mechanical properties and appearance up to 40 parts per hundred resins in roll-mill-processed sheets. In addition, ethylene glycol, which is used as a solvent in glycolysis, can be reused up to three times without the additional removal of BHET. This study demonstrated an industrially applicable method for simultaneously recycling PVC and PET from widely used tarpaulins. Published by Elsevier B.V. All rights reserved.

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