Bio-based high gas barrier polyesters based on furandicarboxylic acid: Trade-off between ethylene and propylene diols

A series of bio-based poly(ethylene-co-propylene furandicarboxylate) (PEPF) copolyesters with different compositions were synthesized from dimethyl-2,5-furandicarboxylate, ethylene glycol and 1,3-propanediol by transesterification and melting polycondensation. Their chemical structure, composition and sequence distribution were confirmed by H-1 NMR and C-13 NMR. The results of GPC showed that the obtained copolyesters had a high number average molecular weight between 25000 g/mol and 30900 g/mol. The thermal properties characterized by DSC showed that the T-g increased with the mole fraction of EF from 64.4 degrees C for PEPF-23 to 83.2 degrees C for PEPF-84 as well as the samples displayed a high Young's modulus between 2800 and 3360 MPa and tensile strength between 56 and 89 MPa. Furthermore, the PEPF copolyesters exhibited excellent CO2, O-2 and H2O barrier properties compared with poly(ethylene terephthalate) with the BIFp of 8.7-10 times, 3.7-4.4 times and 1.5-1.6 times, respectively. The transparency of PEPFs was up to 89% by cutoff at 700 nm and had better solvent resistance. This work builds a bridge between poly(ethylene 2,5-furandicarboxylate) and poly(propylene 2,5-furandicarboxylate) and PEPFs owned excellent thermo-mechanical and gas barrier properties could be used in food packaging fields.