MISCIBILITY, CRYSTALLIZATION AND MORPHOLOGY OF POLY(BETA-HYDROXYBUTYRATE) POLY(D,L-LACTIDE) BLENDS/

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