Synthesis of bio-based polyesters with crystallization properties comparable to poly(butylene terephthalate)

To enhance the crystallization of poly(butylene 2,5-furandicarboxylate) (PBF) thus substitute its petroleum-based analogue poly(butylene terephthalate) (PBT), a series of high molecular weight poly(butylene-co-1,4-cyclohexanedimethylene 2,5-furandicarboxylate) (PBCF) copolyesters with low contents (0–19 mol%) of 1,4-butanediol (BDO) are synthesized from 2,5-furandicarboxylic acid (FDCA), 1,4-cyclohexanedimethylene (CHDM) and BDO. Their chemical structures and compositions are confirmed by nuclear magnetic resonance ( 1 H NMR and 13 C NMR). Their number average molecular weights are from 20,500 to 36,100 g/mol with the polydispersity index ( Ð ) of 1.67–1.99. The thermal stability and crystallization behaviors are investigated by thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC). Results show that PBCFs demonstrate comparable crystallization rate to PBT as the crystallization half time is from 18 to 29 s and the melting enthalpy is 34.1–41.4 J/g as well as the higher melting temperature of 238–263°C than 225°C for PBT. In addition, PBCFs exhibit excellent mechanical properties of tensile modulus between 1220 and 1510 MPa. These investigations suggest that a moderate amount CF unit can improve the melting temperature and enhance the originally weak crystallizability of furan-based polyesters. Generally, PBCFs can be the engineering plastic with satisfied thermal and mechanical performance.