Synthesis, Thermal and Mechanical Properties of Fully Biobased Poly (hexamethylene succinate-<i>co</i>-2,5-furandicarboxylate) Copolyesters

Poly (hexamethylene succinate) (PHS) is a biobased and biodegradable polyester. In this research, two fully biobased high-molecular-weight poly (hexamethylene succinate-co-2,5-furandicarboxylate) (PHSF) copolyesters with low hexamethylene furandicarboxylate (HF) unit contents (about 5 and 10 mol%) were successfully synthesized through a two-step transesterification/esterification and polycondensation method. The basic thermal behavior, crystal structure, isothermal crystallization kinetics, melting behavior, thermal stability, and tensile mechanical property of PHSF copolyesters were studied in detail and compared with those of PHS. PHSF showed a decrease in the melt crystallization temperature, melting temperature, and equilibrium melting temperature while showing a slight increase in the glass transition temperature and thermal decomposition temperature. PHSF copolyesters displayed the same crystal structure as PHS. Compared with PHS, PHSF copolyesters showed the improved mechanical property. The presence of about 10 mol% of HF unit increased the tensile strength from 12.9 ± 0.9 MPa for PHS to 39.2 ± 0.8 MPa; meanwhile, the elongation at break also increased from 498.5 ± 4.78% to 1757.6 ± 6.1%