Chemical Recycling of Tritan Copolyester

Abstract

Tritan is a commodity copolyester that has recently entered the market as an alternative to bisphenol A polycarbonate (BPA-PC). The chemical recycling of Tritan was examined, and four methods for deconstructing Tritan to polymerizable monomers were demonstrated. Tritan can be deconstructed using literature conditions employed for the chemical recycling of polyethylene terephthalate (PET) to produce bis(2-hydroxyethyl) terephthalate (BHET) and dimethyl terephthalate (DMT), although isolated yields were found to be low. Depolymerization of Tritan using its constituent diols, cyclohexanedimethanol (CHDM) and 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCB), produced a pair of terephthalate diesters that could be directly repolymerized to Tritan. The same approach was used to upcycle waste PET to Tritan. Both the recycled and upcycled Tritan had similar properties to commercial Tritan, demonstrating the circularity of the process. The behavior of Tritan in a stream of mixed plastic waste was also investigated, and Tritan was successfully separated using a combination of simple physical and chemical methods. This work demonstrates a circular process to chemically recycle an important emerging commodity polymer.