Enzyme-catalyzed preparation of dimeric acid polyester polyol from biodiesel and its further use in the synthesis of polyurethane

Abstract

Biomass-based new materials have attracted wide attention due to their renewable characteristics. In this study, the synthesis of dimeric acid polyester polyol (DAPP) was conducted through the polymerization of dimeric acid methyl ester (DAME) and ethylene glycol (EG) using Novozym 435 as a catalyst. DAME was synthesized from Chinese tallow kernel oil biodiesel and purified via molecular distillation. To examine the effects of different parameters on the polymerization reaction, both single factorial experiments and response surface methodology (RSM) were employed. The optimized conditions were a Novozym 435 dosage of 2.9% (w/w), reaction temperature of 70 °C, molar ratio of EG–DAME of 2.2 : 1.0, and reaction time of 9.7 h. The highest hydroxyl value of the obtained DAPP was 87.47 mg KOH g⁻¹. Its molecular weight and acid value were 1275 g mol⁻¹ and 0.56 mg KOH g⁻¹. The product was further confirmed by FTIR and NMR. Then, the synthesized DAPP was refined into polyurethane (PU) with isophorone diisocyanate (IPDI). The TGA analysis of the synthetic polyurethane showed good thermostability. At the initial heating stage, no volatile constituents escaped. With an increase in temperature, thermal decomposition was divided into two stages: the first stage at 240–370 °C and the second at 370–480 °C. When the temperature reached 480 °C, the polyurethane was completely decomposed without any residue. DSC analysis also indicated that polyurethane had good performance at lower temperatures, with a low glass transition temperature of −52 °C, and there was only one peak, suggesting that the polyurethane is suitable for use in the coating industry.