Co-pyrolysis mechanism of polyester enameled wire and PVC: A joint experimental and theoretical investigation

Abstract

For the recovery of enameled wire, pyrolysis is a resource-friendly and effective process. However, because waste enameled wires are typically recovered from e-waste, a minor number of wires and cables are usually present. As a result, co-pyrolysis of the paint film and wire and cable sheaths is inevitable during the pyrolysis recovery of waste enameled wires. Polyethylene terephthalate (PET) polyester enameled wire and polyvinyl chloride (PVC) were chosen as representatives of enameled wire and cable sheath materials, respectively. The pyrolysis characteristics and pyrolysis kinetic parameters of enameled PET (EPET) wire paint, PVC, and Mixture (a mixture of the two materials, mEPET: mPVC = 9:1) were investigated using TG and various kinetic analysis methods. The combined pyrolysis index and Py-GC/MS were used to assess the co-pyrolysis of EPET and PVC and the products. The pyrolysis of EPET is adversely affected by the presence of PVC throughout the process; however, the presence of Cu in EPET may facilitate the HCl removal reaction of PVC. The co-pyrolysis products of EPET and PVC are more complex, and according to the different main functional groups, can be divided into monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, phenols, ketones, aldehydes, alcohols, esters, carboxylic acids, chlorides, and others. Finally, density functional theory calculations were used to explore the co-pyrolysis mechanism of PET and PVC as well as the creation mechanism of various pyrolysis products. The catalytic mechanism of Cu contained in EPET on PET and PVC was explained from the perspective of electrostatic potential. This study provides a theoretical foundation and comprehensive reference for the pyrolysis and recycling of waste enameled wires.