Catalytic Effect on Simplified Chemical Recycling of Poly(butylene terephthalate)

Chemical recycling plays a crucial role in reducing plastic pollution, lowering CO₂ emissions, and minimizing the overall carbon footprint associated with the circular economy. Poly(butylene terephthalate) (PBT) is a common candidate for chemical recycling, as it is used in various applications that benefit from closed-loop recycling. However, traditional recycling methods often require high catalyst loadings and labor-intensive purification processes. These factors increase the material and energy inputs needed, which undermines both economic viability and environmental sustainability. This study aims to closely examine the de- and repolymerization processes involved in producing recycled PBT (rPBT) within a single reactor and step. The kinetics of this recycling process were systematically investigated by evaluating the effects of depolymerization time, the stoichiometry of 1,4-butanediol, and the presence of catalysts. Both catalytic and noncatalytic conditions were analyzed to understand the intermediate composition, molecular weight development, as well as the thermal and mechanical properties of the recycled rPBT. The findings provide valuable insights for establishing baselines without an added depolymerization catalyst and highlight key parameters that enable the production of high-quality recycled materials while reducing the need for extensive purification.