Degradation Analyses of Poly(3-hydoxybutyrate-co-4-hydroxybutyrate) and Its Blends with Poly(butylene succinate)

The thermal, enzymatic, hydrolytic and soil degradation of poly(3-hydoxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) and its blends with poly(butylene succinate) (PBS) were studied to examine the thermal stability and degradability of the materials. Weight loss and surface morphology including SEM, AFM, and POM were evaluated to reveal the structural change in each degradation process. For thermal degradation, results showed that PBS can improve thermal stability of P(3HB-co-4HB) and provide a wider range of processing temperature for the blends. For enzymatic degradation, lipase used in this study is more specific to PBS, and thus degradation of PBS composition in the blends was more and faster than P(3HB-co-4HB). For hydrolytic degradation, the spherulite size and/or the composition of blends played a more important role than crystallinity in the hydrolysis process. For soil degradation, P(3HB-co-4HB) had faster degradation than PBS because of the presence of enzymes with higher specificity to P(3HB-co-4HB) in the tested soil. In conclusion, the results showed that P(3HB-co-4HB)/ PBS blends have relatively good thermal stability and can be degraded by enzymes and water, which support their potential use as biodegradable packaging materials.