Novel potentially biobased aliphatic−aromatic copolyesters poly(butylene succinate-co-butylene furandicarboxylate)
(PBSFs) in full composition range were successfully synthesized from 2,5-furandicarboxylic acid (FA), succinic acid (SA),
and 1,4-butanediol (BDO) via an esterification and polycondensation process using tetrabutyl titanate (TBT) or TBT/La(acac)3
as catalyst. The copolyesters were characterized by size exclusion chromatography (SEC), Fourier transform infrared (FTIR), 1H
NMR, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and their tensile properties were also
evaluated. The weight average molecular weight (Mw) ranges from 39 000 to 89 000 g/mol. The copolyesters are random
copolymers whose composition is well controlled by the feed ratio of the diacid monomers. PBSFs have excellent thermal
stability. The glass transition temperature (Tg) increases continuously with ?BF and agrees well with the Fox equation. The
crystallizability and Tm decrease with increasing butylene furandicarboxylate (BF) unit content (?BF) from 0 to 40 mol %, but
rise again at ?BF of 50−100 mol %. Consequently, the tensile modulus and strength decrease, and the elongation at break
increases with ?BF in the range of 0−40 mol %. At higher ?BF, the modulus and strength increase and the ultimate elongation
decreases. Thus, depending on ?BF, the structure and properties of PBSFs can be tuned ranging from crystalline polymers
possessing good tensile modulus (360−1800 MPa) and strength (20−35 MPa) to nearly amorphous polymer of low Tg and high
elongation (∼600%), and therefore they may find applications in thermoplastics as well as elastomers or impact modifiers.