Biobased poly(butylene 2,5-furandicarboxylate) and poly(butylene adipate-co-butylene 2,5-furandicarboxylate)s: From synthesis using highly purified 2,5-furandicarboxylic acid to thermo-mechanical properties

To synthesize high quality (co)polyesters derived from 2,5-furandicarboxylic acid (FA), an acetic acid refluxing/pH-swing method was proposed to purify FA. 2-Carboxyl furfural and other impurities were removed completely from FA with this method. Using highly purified FA, biobased polyester poly(butylene fumadicarboxylate) (PBF) and aliphatic-aromatic copolyesters poly(butylene adipate-co-butylene 2,5-furandicarboxy-late)s (PBAFs) were synthesized via melt (co)polycondensation. The (co) polyesters were characterized with GPC, FTIR, H-1 NMR, DSC and TGA, and their tensile mechanical properties were also assessed. The copolyesters possess random chain structure, monomer feed ratio-controlled copolymer composition and excellent thermal stability (T-d.5% > 340 degrees C) in full composition range. Both BA-rich and BF-rich PBAFs are crystalline polymers. The crystallizability decreases with composition, up to nearly amorphous at moderate phi(BF) (40-60%). PBAFs with phi(BF) no more than 50% exhibit obvious high-elastic deformation and rebound resilience, and possess tensile properties (E 18-160 MPa, sigma(b) 9-17 MPa, epsilon(b) 370-910%) comparable to poly(butylene adipate). PBAFs with higher phi(BF) behave like nonrigid plastics with low tensile moduli (42-110 MPa), moderate strength (30-42 MPa) and high elongation at break (310-470%). In comparison, PBF is a strong and tough thermoplastic having balanced mechanical properties, namely, much higher tensile modulus (1.9 GPa) and strength (56 MPa) and high elongation at break (260%). It seems necessary and effective to use highly purified FA for synthesizing high performance FA-derived (co)polyesters. 2014 Elsevier Ltd. All rights reserved.