Sustainable Immiscible Polylactic Acid (PLA) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) Blends: Crystallization and Foaming Behavior

Tailoring the properties of polylactic acid (PLA) by blending with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a practical methodology to improve the foaming behavior of PLA. PHBV is biodegradable, nontoxic, biocompatible, and made naturally by bacteria. This study investigates the influence of PLA/PHBV blends on the sorption behavior, crystallization behavior, dynamic mechanical properties, and autoclave foaming. It was shown by atomic force microscopy-infrared (AFM-IR) and dynamic mechanical thermal analysis (DMTA) measurements that PHBV and PLA are immiscible. The results from differential scanning calorimetry (DSC), DMTA, and AFM-IR have been correlated to the foaming behavior of PLA at different PHBV contents (10–40%). With increasing PHBV content in the blend, the foam density slightly increased and smaller cell size and an increased foam cell nucleation rate were found. Additionally, the foaming behavior was correlated with thermograms of the foamed samples. Finally, the study showed that PHBV can improve the foam morphology of PLA-based foams.