Miscibility and crystallization behavior of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(vinyl acetate) blends

The miscibility and crystallization behavior of poly(3-hydroxybutyrate-co-3-hy(iroxyvalerate) (P(HB-co-HV))/poly(vinyl acetate) (PVAc) blends have been investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). It was found that P(HB-coHV)/PVAc blends were miscible in the melt over the whole compositions. Thus the blend exhibited a single glass transition temperature (T-g), which increased with increasing PVAc composition. The spherulitic morphologies of P(HBco-HV)/PVAc blends indicated that the PVAc was predominantly segregated into P(HB-co-HV) interlamellar or interfibrillar regions during P(HB-co-HV) crystallization because of the volume-filled spherulites. As to the crystallization kinetics study, it was found that the overall crystallization and crystal growth rates decreased with the addition of PVAc. The kinetics retardation was primarily attributed to the reduction of chain mobility and dilution of P(HB-co-HV) upon mixing with higher T PVAc. The overall crystallization rate was predominantly governed by the spherulitic growth rate and promoted by the samples treated with the quenched state because of the higher nucleation density. (c) 2006 Wiley Periodicals, Inc.