Work

Upcycling of Waste Poly(ethylene Terephthalate): Ammonolysis Kinetics of Model Bis(2‐Hydroxyethyl Terephthalate) and Particle Size Effects in Polymeric Substrates

Year: 2025

Type: article

Abstract: Chemical upcycling of poly(ethylene terephthalate) (PET) through ammonolysis is pursued. Model studies are conducted on bis(2‐hydroxyethyl) terephthalate reacting with ammonia in the presence of excess ethylene glycol (EG) to form terephthalamide. Reactions conducted over the range of temperatures from 50 to 125 °C yield pre‐exponential factors of A1 = 758 ± 120 L mol−1 h−1/A2 = 1033 ± 220 L mol−1 h−1 and activation energies of Ea1 = 22.1 ± 1.5 kJ mol−1 and Ea2 = 26.5 ± 2.1 kJ mol−1. Diffusional limitations are explored using particle sizes in the ranges of 1800–2500 μm, 250–600 μm, and 150–250 μm. Data from the particle size experiments is combined with the rate constants determined from the model studies to construct an effectiveness factor. Diffusivity is used as a fitting parameter, resulting in an estimated value of 1.37 ± 0.48 E‐7 cm2 s−1 for ammonia in PET at 100 °C, which compares well to related literature values. Diffusional limitations are of profound importance; for particles of only 1 millimeter in average thickness, the conversion rate is decreased by a factor of ten! The comprehensive understanding of the ammonolysis of PET in EG provided can play an important role in improving material reuse and fostering a more circular economy.

Source: ChemSusChem

DOI: 10.1002/cssc.202500509

Authors: Richard‐Joseph L. Peterson, Elanna P. Neppel, Daniel Holmes, P. Anh Trinh, Robert Y. Ofoli, John R. Dorgan

Institution: Michigan State University

Language: English

Topic: Polymer crystallization and properties

Subfield: Polymers and Plastics

Field: Materials Science

Domain: Physical Sciences

SDG: Responsible consumption and production

Open Access status: hybrid

Estimated APC paid: $4,550