From Fossil Resources to Renewable Resources: Synthesis, Structure, Properties and Comparison of Terephthalic Acid-2,5-Furandicarboxylic Acid-Diol Copolyesters

Novel copolyesters were successfully synthesized from terephthalic acid (TPA), 2,5-furandicarboxylic acid (FDCA) and ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and 1,8-octanediol via direct esterifi cation method by using tetrabutyl titanate (TBT) as catalyst. The copolyesters were characterized by nuclear magnetic resonance spectroscopy (¹H-NMR), gel permeation chromatography (GPC), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile tests. The results of GPC showed that all of the copolyesters had high molecular weight, with an average molecular weight (Mw) more than 1×10⁴ g/mol. The results of ¹H-NMR showed that the copolyesters were random copolymers which compositions were well controlled by the feed ratio of the diacid monomers, and the degrees of randomness (B) values were near to 1.0 and 1.40. The results of DSC showed that all of the copolyesters had one glass transition temperature (T_g) and the T_gs were between those of corresponding homopolyesters. The results of TGA showed that the copolyesters were thermally stable up to 370°C and had similar thermal stabilities to corresponding homopolyesters. The results of tensile tests showed that some of the PETF and PTTF copolyesters had better tensile strength and tensile modules, and PBTF, PHTF and POTF copolyesters had higher elongation at break.