Recycling PVC with scCO₂: From Soft to Rigid PVC

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Chemistry

Background:

• Plasticizers in poly(vinyl chloride) (PVC) hinder effective recycling.
• Developing sustainable methods for plasticizer removal is crucial for circular economy initiatives.

Purpose of the Study:

• To investigate the efficiency of supercritical carbon dioxide (scCO2) extraction for removing plasticizers from PVC.
• To assess the impact of scCO2 extraction on the purity and properties of recycled PVC.

Main Methods:

• Extraction experiments using supercritical carbon dioxide at pressures from 100 to 500 bar and temperatures from 75 to 110 °C.
• Characterization of extracted PVC using gel permeation chromatography, rheology, tensile testing, and scanning electron microscopy.
• Process modeling using the Sovová model to describe the extraction kinetics.

Main Results:

• Achieved over 98% extraction efficiency for bis(2-ethylhexyl) phthalate (DOP) from PVC.
• Produced PVC samples with over 99.5% purity.
• The Sovová model accurately described the supercritical extraction process.

Conclusions:

• Supercritical carbon dioxide is a highly effective and efficient method for removing plasticizers from PVC.
• The scCO2 extraction process maintains the integrity of PVC's physical and molecular properties, making it suitable for recycling.
• This technology offers a promising route for enhancing the recyclability of PVC and promoting a circular economy.