Miscibility, crystallization and morphology of poly(beta-hydroxybutyrate)/poly(d,l-lactide) blends

The miscibility, crystallization and morphology of poly(beta-hydroxybutyrate) (PHB)/poly(d,l-lactide) (PLA) blends were investigated by means of differential scanning calorimetry, polarizing optical microscopy and scanning electron microscopy studies. The results indicated that PHB/PLA blends prepared by casting a film from a common solvent at room temperature were immiscible over the range of compositions studied, while the melt-blended sample prepared at high temperature showed some evidence of greater miscibility. The crystallization of PHB in the blends was affected by the level of addition of PLA. The thermal history caused a depression of the melting point and a decrease in the crystallinity of PHB in the blends. Compared with plain PHB, the blends exhibited a certain improvement in mechanical properties.