Poly (ethylene terephthalate) thermo-mechanical and thermo-oxidative degradation mechanisms

Author(s)

Romao, Wanderson ^[1] ; Franco, Marcos F. ^[1] ; Corilo, Yuri E. ^[2] ; Eberlin, Marcos N. ^[2] ; Spinace, Marcia A. S. ^[1] ; De Paoli, Marco-A. ^[1]

Affiliation

^[1] Univ Estadual Campinas, Lab Polimeros & Reciclagem, Inst Quim, BR-13084971 Campinas, SP - Brazil

^[2] Univ Estadual Campinas, Lab ThoMSom Espectrometria Massas, Inst Quim, BR-13084971 Campinas, SP - Brazil

• Document type: Journal article
• Source: Polymer Degradation and Stability; v. 94, n. 10, p. 1849-1859, OCT 2009.
• Web of Science Citations: 46

Abstract

(1)H NMR and MALDI-TOF MS measurements were used to study the thermo-mechanical and thermo-oxidative degradation mechanisms of bottle-grade PET (btg-PET). In the thermo-oxidative degradation, the concentration of low molar mass compounds increased with time and the main products were cyclic and linear di-acid oligomers. In the thermo-mechanical degradation, the main-chain scission reactions affect the stability of the cyclic oligomers. One of the most important bottle-grade PET co-monomers is diethylene glycol (DEG), which is a ``reactive site'' in the thermal degradation of btg-PET. The DEG co-monomer was shown to be the precursor to colour changes in btg-PET, owing to the attack by molecular oxygen on the methylenic protons adjacent to the ether oxygen atoms of DEG. This behaviour was observed in the thermo-oxidative degradation process in which the degradation of DEG causes the release of hydroxyl radicals in the polymeric matrix, thereby producing mono- and di-hydroxyl substituted species. This was also observed in the thermo-mechanical degradation process. (c) 2009 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 04/15084-6 - Polymeric materials of low environmental impact
• Grantee: Marco-Aurelio de Paoli
• Support Opportunities: Research Projects - Thematic Grants