Development and Characterization of Fully Renewable and Biodegradable Polyhydroxyalkanoate Blends with Improved Thermoformability

[EN] Poly(3-hydroxybutyrate-co-3-valerate) (PHBV), being one of the most studied and commercially available polyhydroxyalkanoates (PHAs), presents an intrinsic brittleness and narrow processing window that currently hinders its use in several plastic applications. The aim of this study was to develop a biodegradable PHA-based blend by combining PHBV with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), another copolyester of the PHA family that shows a more ductile behavior. Blends of PHBV with 20% wt., 30% wt., and 40% wt. of PHBH were obtained by melt mixing, processed by cast extrusion in the form of films, and characterized in terms of their morphology, crystallization behavior, thermal stability, mechanical properties, and thermoformability. Full miscibility of both biopolymers was observed in the amorphous phase due to the presence of a single delta peak, ranging from 4.5 degrees C to 13.7 degrees C. Moreover, the incorporation of PHBH hindered the crystallization process of PHBV by decreasing the spherulite growth rate from 1.0 mu m/min to 0.3 mu m/min. However, for the entire composition range studied, the high brittleness of the resulting materials remained since the presence of PHBH did not prevent the PHBV crystalline phase from governing the mechanical behavior of the blend. Interestingly, the addition of PHBH greatly improved the thermoformability by widening the processing window of PHBV by 7 s, as a result of the increase in the melt strength of the blends even for the lowest PHBH content.This research was supported by MCIN/AEI/10.13039/501100011033 and FEDER "Una manera de hacer Europa", project number RTI2018-097249-B-C21. Moreover, this work has also been granted with the financial support of the Generalitat Valenciana (project AICO/2021/045), H2020 EU Project YPACK (H2020-SFS-2017-1, Reference 773872) and by the Universitat Jaume I (project UJI-B2019-44). K.S-A. would like to acknowledge the MCIN/AEI/10.13039/501100011033 and FSE "El FSE invierte en tu futuro" for their FPI fellowship (PRE2019-091448). S.T-G. acknowledges the Spanish Ministry of Science, Innovation and Universities (MICIU) for the funding received during their Juan de la Cierva-Incorporacion contract (IJCI-2016-29675).Feijoo, P.; Samaniego-Aguilar, K.; Sánchez-Safont, E.; Torres-Giner, S.; Lagaron, JM.; Gamez-Perez, J.; Cabedo, L. (2022). Development and Characterization of Fully Renewable and Biodegradable Polyhydroxyalkanoate Blends with Improved Thermoformability. Polymers. 14(13):1-24. https://doi.org/10.3390/polym14132527124141