Plant oil fillers toughened poly(3-hydroxybutyrate) green biocomposites

Poly(3-hydroxybutyrate) (PHB) faces a significant challenge of intrinsic brittleness, thus limiting its widespread applicability. This challenge can be surmounted by incorporating various nanofillers into the PHB matrix to tune the mechanical performance. However, many of these fillers are produced using unsustainable, nonenvironmentally friendly methods. Herein, we employed a green process to develop castor-oil-based fillers, CO -g -DLA, and CO-P(CL-co-DLA)-PDLA (CO -r -DLA), for the toughening of the PHB matrix. Impressively, the addition of 20% of these fillers increases the elongation at the break by 13-fold through forming elongated fibril structures and enhanced interfacial interactions between fillers and the matrix, accompanying by a substantial reduction on the PHB's brittleness through shear yielding and fibrillation. These are confirmed by Small-Angle Xray Scattering (SAXS) results, showing significant copolymer-induced microstructural changes in the matrix. The biodegradable PHB biocomposite developed in this study offers a promising green alternative to conventional plastics, especially in sustainable packaging.