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

Abstract

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 °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.

Poly(butylene terephthalate)/polylactic acid based copolyesters and blends: miscibility-structure-property relationship

“…Moreover, the presence of a small amount of OLA in the obtained material has also been verified with the 1 H NMR investigations. Similar phenomenon has been reported for other aromatic-lactic acid copolymers, such as poly(ethylene-terephthalate)-co-poly (lactic acid) [24], poly(ethylene-2,4-furanodicarboxylate)-co-poly(lactic acid) [28] and poly(butylene-2,4furanodicarboxylate)-co-poly(lactic acid) [29]. The influence of different feed ratios on intrinsic viscosity, GPC and density results are also shown in Table 1.…”

“…The tensile strength at yield decreased from 46.6 to 25.2 MPa, whilst tensile strength at break decreased from 45.7 to 19.8 MPa for PBT-b-PLA 10 and PBT-b-PLA 30, respectively. This is in agreement with the study of Hu et al [29] dealing with comparable aliphatic-aromatic systems. The enhancement of ductility in copolymer series is also highlighted by the decrease in Young's modulus from 3.1 (PBT homo polymer) to 1.5 GPa (PBT-b-PLA 30).…”

“…It is strongly suggested that short blocks copolymers investigated in present work behave in similar manner as random copolymers in terms of thermal stability. A similar tendency was reported earlier by Hu et al [29] for PBF-PLA copolyesters.…”

“…This effect is not so evident in PLA and copolymers with higher amount of PLA (20 and 30 wt%). Hu et al [29] in their DMTA analysis on PBFLA copolymers, also observed that with increasing concentration of PLA, crystallization during heating is inhibited. They found that cold crystallization could not be identified if PBT sequence length is less than 4.…”

“…Moreover, few efforts have been dedicated to the synthesis of aliphatic-aromatic copolymers via polycondensation starting from L-lactic acid oligomer (OLLA) and hydroxyl terminated poly(ethylene terephthalate) [24,25], poly(butylene terephthalate) [26] or poly(trimethylene terephthalate) prepolymers [27]. More recently, due to the growing popularity of biobased aromatic furanic homologues, a few studies have been focused on copolymerization of PLA with poly(ethylene 2,5-furanodicarboxylate) (PEF) [28] and poly (butylene 2,5-furanodicarboxylate) (PBF) [29]. Special attention has been paid to the degradation studies of the above-mentioned systems.…”