Recycling PVC with scCO₂: From Soft to Rigid PVC

This study explores using extraction with supercritical carbon dioxide to remove plasticizers from poly(vinyl chloride) (PVC), with the aim to enhance recycling processes. Experiments were performed at 100 to 500 bar with temperatures varying from 75 to 110 °C. The results show that continuous supercritical carbon dioxide efficiently removes bis(2-ethylhexyl) phthalate (DOP) from PVC with extraction efficiencies of more than 98% which resulted in PVC samples with over 99.5% purity. A process model based on the Sovová model accurately describes the extraction process. The impact of the extraction process on polymer properties and associated molecular structures like viscosity, morphology, and mechanical properties was also evaluated using gel permeation chromatography, rheology, tensile test, and scanning electron microscopy.