Studies on the thermal degradation mechanism of polyethylene terephthalate and its 2-carboxy ethyl (phenyl) phosphinic acid copolymers. (December 2022)

• Record Type: Journal Article
• Authors: Ma, Tianyi; Wang, Rui; Wang, Wenqing; Gu, Weiwen; Yuan, Ye; Zhang, Anying; Wei, Jianfei
• Is Part Of: Polymer degradation and stability. Volume 206(2022)
• Publication Date: 2022-12
• Subjects: Thermal pyrolysis mechanism -- Quantum chemistry -- Polyester -- Flame retardant -- CEPPA; Polymers -- Deterioration -- Periodicals; Stabilizing agents -- Periodicals; Polymères -- Dégradation -- Périodiques; Stabilisants -- Périodiques; 668.9
• DOI: 10.1016/j.polymdegradstab.2022.110185
• Languages: English
• ISSNs: 0141-3910

Abstract

Highlights: 1. Density functional theory was used for PET and CEPPA-PET thermal degradation. 2. TG-MS, TG-IR and Py-GC-MS of PET and CEPPA-PET were also investigated. 3. Homolytic cleavage reaction was dominated firstly, followed by β-cis-elimination for PET. 4. More 4-carboxybenzaldehyde detection due to P free radicals in CEPPA-PET. Abstract: In this paper, the thermal degradation of polyethylene terephthalate (PET) and 2-carboxy ethyl (phenyl) phosphinic acid (CEPPA)-PET copolymer was comparatively studied by TG-MS, TG-IR, and Py-GC-MS methods. A theoretical study on the thermal degradation mechanism of PET and CEPPA/PET copolymer was carried out using density functional theory (DFT). In an inert atmosphere, the homolytic cleavage reaction of PET was dominant at first, followed by the β-cis-elimination reaction, which resulted in the generation of abundant benzoic acid and 4-carboxybenzaldehyde, instead of terephthalic acid, as the main products. However, CEPPA-PET degraded easier and captured specific free radicals changing the homolytic cleavage reaction path and generating more 4-carboxybenzaldehyde. The proposed mechanism was consistent with experimental observations of small molecular gases, benzoic acid, and 4-carboxybenzaldehyde as the main degradation products. Graphical abstract: Image, graphical abstract