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Curable precursors derived from chemical recycling of poly(ethylene terephthalate) and polylactic acid and physical properties of their thermosetting (co)polyesters


Curable precursors for production of thermosetting (co)polyesters are developed based on poly(butylene adipate) (PBA), poly(ethylene terephthalate), and poly(lactic acid) (PLA). The precursors are prepared from methacrylation of their hydroxyl-terminated oligomers. These include commercial HO-capped PBA prepolymer (HO-PBA), and bis-2-hydroxyethyl terephthalate (BHET) and glycolized PLA (GPLA), which are obtained from glycolysis reactions of their post-consumer products and original resin. The optimal conditions for methacrylation of each prepolymer, i.e., molar ratios of prepolymer to methacrylic anhydride (MAAH), temperature and time, are examined. The most efficient conditions are 1:4/120 °C/3 h (HO-PBA), 1:2.5/120 °C/2 h (BHET), and 1:4/140 °C/3 h (GPLA), respectively. These conditions are justified, where the highest degree of substitution and double bond content are obtained without self-curing side reaction. The resulting methacrylated precursors from HO-PBA and BHET are isothermally cured faster than those of GPLA. Thermosetting copolyesters developed from binary mixtures of the precursors possess tunable thermal stability, and physical and mechanical properties. The degradable copolyesters can be applied in various applications, especially in packaging and agricultural fields.

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Financial support of this work is provided by the National Research University Project of CHE (AM1029A) and National Metal and Materials Technology Center, NSTDA (Project No. MT-B-52-POL-09-453-G). O.T. gratefully acknowledges financial supports from the Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University, and the National Research University Project of CHE (AM1029A). P.O. acknowledges supports from the Center of Excellence in Materials and Plasma Technology (M@P Tech), Thammasat University.

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Correspondence to M. Opaprakasit.

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Torpanyacharn, O., Sukpuang, P., Petchsuk, A. et al. Curable precursors derived from chemical recycling of poly(ethylene terephthalate) and polylactic acid and physical properties of their thermosetting (co)polyesters. Polym. Bull. 75, 395–414 (2018).

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