Rapid Microwave-Assisted Chemical Recycling of Poly(p-Phenylene Terephthalamide)

Abstract

Back-to-monomer chemical recycling of polymers is crucial in achieving a circular plastics economy. Herein, we report the rapid microwave-assisted depolymerization of poly(p-phenylene terephthalamide) (PPTA), also known as Twaron or Kevlar. The alkaline hydrolysis of PPTA was conducted in a microwave reactor at temperatures ranging from 240 to 260 °C with reaction times of 1–15 min. The highest conversion (96%) was found after 15 min at 260 °C. The resulting monomers terephthalic acid and p-phenylenediamine were successfully purified (>99% purity) in good yields using extraction and precipitation methods. This work presents the fastest depolymerization of PPTA to date under relatively mild conditions, thereby encouraging a circular value chain for PPTA.