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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.

Curable precursors are prepared from chemical recycling of degradable polylactic acid (PLA) for development of aliphatic polyester thermoset materials. PLA resin (NatureWork 4042D) was de-polymerized via glycolysis under various conditions to produce PLA glycolysates (GlyPLAs), whose chain-ends mainly consist of hydroxyl groups with $$\bar{M}_{n}$$ ranging from 3,600 to 17,000 g/mol. Unsaturated double bonds (DB) were introduced into GlyPLA structures by end-capping with methacrylic anhydride to generate curable LA-precursors. The end-capping efficiency is strongly dependent on the molecular weight of GlyPLAs, where smaller-sized glycolysates produce LA-precursors with higher DB content. Curing behaviors of the precursors are thoroughly examined. DSC and FTIR results show that curing reactions at 140 °C are completed after 2 h for all samples. Results on gel fraction indicate that LA-precursor with $$\bar{M}_{n}$$ ~ 3,600 g/mol is the most effective candidate for producing network products with high crosslink density.