Poly(ethylene terephthalate) is a semi-crystalline polyester made from terephthalic acid and ethylene glycol, and it is the polymer behind most beverage bottles and polyester textile fibre. Its rigid aromatic unit and its ester linkage give a high melting point together with a glass transition well above room temperature [1]. The crystallisation rate of the homopolymer is slow, so a nucleating agent or a comonomer is added to reach the crystallinity needed for a bottle or for a drawn fibre [2]. Hydrolysis and glycolysis cleave the ester bond and return the monomers, and these routes are operated at scale for bottle waste [3]. The amorphous, unoriented form suits products where clarity matters, and a hot-fill container must be heat-set to avoid shrinkage above the glass transition [4]. Antimony or titanium serves as the polycondensation catalyst and remains in the resin, which is a concern for food contact and a complication for chemical recycling [5].
- terephthalic acid
- ethylene glycol
- semi-crystalline polyester
- hydrolysis
- glycolysis
- bottle grade
- intrinsic viscosity
References
- Igberaese, O.J.; Orhorhoro, E.K.; Lucky, C.; Godswill, O.O.; The Design and Fabrication of a used Polyethylene Terephthalate (PET) Bottle Washing and Sterilizing (Recycling) Machine. International Academic Journal of Science and Engineering 2019, 06, 119-131, 10.9756/iajse/v6i1/1910012.
- Guo, Z.; Wu, J.; Wang, J.; Chemical degradation and recycling of polyethylene terephthalate (PET): a review. RSC Sustainability 2025, 3, 2111-2133, 10.1039/d4su00658e.
- Hu, A.H.; Ting, C.Y.; Ouattara, A.; Chen, W.T.; Kuo, C.H.; Life Cycle Assessment of Recycling Polyethylene Terephthalate (PET): A Comparative Case Study in Taiwan. Recycling 2025, 10, 98, 10.3390/recycling10030098.
- Umdagas, L.; Orozco, R.; Heeley, K.; Thom, W.; Al-Duri, B.; Advances in chemical recycling of polyethylene terephthalate (PET) via hydrolysis: A comprehensive review. Polymer Degradation and Stability 2025, 234, 111246, 10.1016/j.polymdegradstab.2025.111246.
- Conroy, S.; Zhang, X.; Theoretical insights into chemical recycling of polyethylene terephthalate (PET). Polymer Degradation and Stability 2024, 223, 110729, 10.1016/j.polymdegradstab.2024.110729.