Depolymerization of a Polypropylene-EPDM Mixture Via Supercritical Water Partial Oxidation

Andrea Crow
Abhay Sardesai
W. Douglas Lilac
Sunggyu Lee, Missouri University of Science and Technology

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One of the major environmental concerns in the polymer industry is the effective disposal or treatment of the spent or waste polymers. One such polymer example is a polypropylene-EPDM (ethylene-propylene-diene-monomer) blend most commonly used in automobile bumpers and other automotive parts. Current treatment methods include pyrolysis and reformation of polymer; however these methods have had limited success. A novel process described in this paper deals with depolymerization of this polymer blend via supercritical water partial oxidation. This process offers the advantages of recovery of monomer, oligomer, and other useful hydrocarbons in a short reaction time with high efficiency. Therefore, this process offers a new avenue not only for disposal of waste polymers, but more importantly for facilitating environmentally sound recovery of monomers that can be made available as raw materials in the petrochemical industry. This paper addressses the depolymerization of 25 wt% EPDM in polypropylene mixture. The experiments are carried out in a 1-Liter Hastelloy-C276 bolt closure reactor. Key issues investigated are the product yield, in particular the selectivity towards propylene and ethylene monomers. The process parameters studied include the amount of oxygen in the feed and reaction time, as well as the reaction temperature and pressure.