Price, Matthew John 
ORCID: 0000-0002-8528-5759
(2023).
Chemical recycling and upcycling of poly(ethylene) terephthalate.
University of Birmingham.
Ph.D.
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Price2023PhD.pdf
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Abstract
Poly(ethylene)terephthalate (PET) is the most commonly used plastic in the world, yet it is almost always (ca. 98%) discarded after use. The millions of tonnes of PET thrown away every day represent a valuable untapped chemical and material resource. In this work the chemical recycling and upcycling by glycolysis and alcoholysis will be explored as routes towards greater utilisation of plastic waste at the end of its lifespan. As a direct result of this study, the particle size is shown to have a significant effect on.
Chapter 1 is a literature review of the state of the art of polymer Chemical Recycling to Monomer (CRM), PET chemical recycling and upcycling and additive manufacturing of chemically degraded polymer.
Chapter 2 is a publication-ready article on the development of a low-temperature alcoholysis process for PET upcycling to functional monomers, and the subsequent crosslinking of these monomers into novel, 3D-printable materials. PET is shown to be upcyclable by alcoholysis using perillyl alcohol and prenol at 120 °C. Upcycled, 3D-printed materials can be derived from the perillyl monomer by formulating it with a three-armed thiol, dye and diluent.
Chapter 3 is a moderate-scale screen of Lewis acid and base combination dual catalysts for PET glycolysis, using metal acetates and amine bases. Moreover, the activity was measured by two different degradation models and these were compared and contrasted. Several catalyst combinations, such as Mg(OAc)2/MTBD and Zn(OAc)2/Im, were shown to have high pseudo-first order rate constants. A well-correlated (R2 = 0.941) model was developed using the M2E3D program for Zn(OAc)2/base catalyst rate constants.
Chapter 4 reports a Density Functional Theory study into the mechanism of PET glycolysis by a selection of bases with zinc acetate. The specific mechanistic pathways were described in detail and structure-property-activity relationships were developed. It was found that the mechanism proceeds via a transition state in which the acetate ligand acts as a base towards the nucleophile, yet remains bound to the metal.
Chapter 5 expands upon the literature’s scope of glycolysis of PET which includes impurities such as dyes, fabrics and flame retardants. The activities of common highly active catalysts were compared and contrasted. The industrial catalyst Zn(OAc)2 / urea (1:4) was found to be most active towards mixed fabric blends. Dyestuffs were found to have at most 15% effect on the rate constant, and flame retardant less than 5%.
Chapter 6 presents a summary of the above chapters’ experimental results, any future work that can be accomplished in the area, and an overview of the problem and solutions presented herein.
| Type of Work: | Thesis (Doctorates > Ph.D.) | |||||||||
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| Award Type: | Doctorates > Ph.D. | |||||||||
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| Licence: | All rights reserved | |||||||||
| College/Faculty: | Colleges (2008 onwards) > College of Engineering & Physical Sciences | |||||||||
| School or Department: | School of Chemistry | |||||||||
| Funders: | Other | |||||||||
| Other Funders: | University of Birmingham | |||||||||
| Subjects: | Q Science > QD Chemistry | |||||||||
| URI: | http://etheses.bham.ac.uk/id/eprint/14311 |
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