Poly(butylene succinate) copolyesters containing cyclic acetalized tartrate units

Abstract

Utilization of carbohydrate derivatives for polymer synthesis has been paid much attention not only because of the huge abundance of resources but also because of the promising biodegradability and biocompatibility of the polymers obtained from them. Of the different natural resources, carbohydrates stand out as highly convenient raw materials because they are inexpensive, readily available, and provide great functional diversity. Poly(butylene succinate) (PBS) and its copolymers are a family of biodegradable polymers with excellent biodegradability, thermoplastic processability and balanced mechanical properties. In this work, copolyesters of PBS were synthesized by taking different feed molar ratio of 2,3-di-O-methylene-L-threitol to 1,4-butanediol with dimethyl succinate, and 2,3-di-O-methylene dimethyl tartrate to dimethyl succinate with 1,4-butanediol. Chemical characterization of copolymers was carried out by NMR, FT-IR, viscosimetry and GPC. The number average molecular weights (Mn) of the polymers were found to vary in the range of 615 × 103 g∙mol-1. The physical properties of PBS materials varied in a wide range depending on their composition. The thermal behavior and the mechanical properties of these polyesters were evaluated and compared with PBS. The PBS copolyesters showed higher glass transition (Tg) and low melt temperatures (Tm) as compared to the parent polyester. Tg varies from -37 to 13 °C depending on the feed ratio of the comonomers. Regarding the mechanical properties, the introduction of cyclic acetal groups caused an increase in the elongation at break of the polyesters, and produced a reduction in the elastic modulus and tensile strength at the same time.