Preparation and property analysis of chemically regenerated polyethylene terephthalate with improved chromaticity. (January 2023)

• Record Type: Journal Article
• Authors: Zhang, Zhou; Zhang, Xuzhen; Huang, Wenjian; Wang, Xiuhua
• Is Part Of: Polymer degradation and stability. Volume 207(2023)
• Publication Date: 2023-01
• Subjects: Polyethylene terephthalate -- Regeneration -- Glycolysis -- Chromaticity -- Catalyst -- Stabilizer; Polymers -- Deterioration -- Periodicals; Stabilizing agents -- Periodicals; Polymères -- Dégradation -- Périodiques; Stabilisants -- Périodiques; 668.9
• DOI: 10.1016/j.polymdegradstab.2022.110229
• Languages: English
• ISSNs: 0141-3910

Abstract

Highlights: Regenerated PET was prepared using waste PET glycolyzed by EG with catalysts and polymerized with stabilizers. Compared with K2CO3 and Ti3(PO4)4, Zn(Ac)2 shows much higher catalyzing activity convinced by conversion of PET and yield of dihydroxyethyl terephthalate. The addition of Zn(Ac)2 and stabilizer could promote and inhibit the generation of diethylene glycol, respectively. The addition or increasing content of Zn(Ac)2 could highly contribute to side redox reactions generating chromic agents and terminal carboxyl agents in rPET comparing with K2CO3 or Ti3(PO4)4, which are conversely inhibited by stabilizers TPP or TMP. Abstract: In order to reveal the yellowing mechanism of regenerated polyethylene terephthalate (rPET) for preparing rPET with improved chromaticity, waste PET was glycolyzed in ethylene glycol with catalysts zinc acetate (Zn(Ac)2 ), potassium carbonate (K2 CO3 ) or titanium phosphate (Ti3 (PO4 )4 ), and rPET was then prepared using the glycolysis products as raw material through polycondensation stabilized with triphenyl phosphate (TPP) or trimethyl phosphate (TMP). The catalyzing activity of three catalysts were investigated based on conversion of waste PET and yield of dihydroxyethyl terephthalate. Nuclear magnetic resonance, thermal analysis and intrinsic viscosity were used for exploring chemical structure of rPET with various catalysts and stabilizers. As for the investigation of redox side reactions in rPET, chromaticity analysis, terminal carboxyl agent content testing, fluorescence spectrum and ultraviolet spectrum are employed. The effect of addition and increasing content of catalysts Zn(Ac)2, K2 CO3 and Ti3 (PO4 )4, as well as stabilizers TPP and TMP on the above redox side reactions causing chromatic agents and terminal carboxyl agents were thoroughly discussed, as a result, the yellowing caused by side effects of rPET and its inhibition mechanism was thus proposed.