Polyhydroxyalkanoates (PHA) are biodegradable polyesters, with attractive characteristics, promising for replacing conventional petroleum-derived polymers. However, two mechanical limitations greatly restrict their broader applications. This research investigates melt blending and reactive extrusion as strategies to address the two mechanical limitations.

The first part focuses on addressing the aging-induced embrittlement problem of PHA. Melt blending PHA grades is investigated as a means of increasing the amorphous fraction, thereby preserving ductility during prolong storage time while retaining a crystallizable matrix.

The second part focuses on addressing the inherently low impact strength of PHA. Reactive extrusion of PHA with flexible biodegradable copolyesters, compatibilized with organic peroxides and other co-agents, are investigated to improve interfacial adhesion. Phase morphology and various additive loadings are investigated to relate phase structure and performance, to identify processing conditions that enhance toughness without excessive crosslinking.