Modification of Poly(butylene 2,5-furandicarboxylate) with Lactic Acid for Biodegradable Copolyesters with Good Mechanical and Barrier Properties

Fully biobased poly(butylene 2,5-furandicarboxylate)-co-poly(lactic acid)s (PBFLAs) of lactic acid composition from 10% to 40% are synthesized. They are subjected to molecular, thermal, diffractometric, degradable and mechanical characterizations. Thermogravimetric analysis shows that PBFLA are thermally stable at least 350 degrees C, much higher than PLA. After the incorporation of lactic acid units, both T-m and crystallization rate decrease with respect to homopolymers. X-ray diffraction measurements indicate that no PLA crystal is present during crystallization. All samples perform better barrier properties with respect to PLA, implying potential application in packaging. These samples behave like semicrystalline plastic in the tensile tests. PBFLA copolyesters show Young's modulus, maximum tensile strength and breakage elongation higher than 1000 MPa, 38 MPa, and 230%, respectively. Such comprehensive mechanical behaviors exceed most biodegradable materials. Lastly, biodegradability could be significantly improved when more than 20% of lactic acid units are introduced into homopolymers.