Biobased aliphatic polyesters are of interest for their biodegradability and potential to offset the use of unsustainable fossil resources. In addition, many of the bio-sourced monomers are inherently less toxic than those used in conventional polymers. In this work, biobased poly(butylene succinate-co-hexamethylene succinate) (P(BS-co-HS)) copolyesters with butylene succinate (BS)/hexamethylene succinate (HS) molar ratios over the entire compositional range were synthesized from succinic acid, butanediol and 1,6-hexanediol using direct melt polycondensation. The chemical and crystalline structure, thermal properties, solubility and mechanical properties of P(BS-co-HS) copolyesters were investigated. The results confirmed successful synthesis of all copolymers, and the melting temperature, glass transition temperature and crystallization temperature of P(BS-co-HS) copolyesters were tunable depending on BS/HS composition. The crystallinity of P(BS-co-HS) copolyesters decreased to a minimum of 6.0% when the BS/HS ratio was close to 1. Moreover, the incorporation of HS altered the tensile failure mechanism from brittle failure for neat PBS to ductile for P(BS-co-HS) copolyesters with HS content higher than 30mol%. The solubility of these biobased copolymers and their thermal, mechanical and crystallization behavior over the full compositional range are disclosed for the first time. The polyesters show promise as greener coatings for biodegradable paper packaging.

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Volume 86, January 2017, Pages 162–172