Infrared analysis on blends of poly(3-hydroxybutyric acid) and stereoregular poly(vinyl alcohol): Influence of tacticity of poly(vinyl alcohol) on crystallization of poly(3-hydroxybutyric acid)

The extents of crystallization of poly(3-hydroxybutyric acid) (P(3HB)) in blends of P(3HB) with stereoregular poly(vinyl alcohol) (PVA) have been studied by means of infared spectroscopy. The degree of crystallinity of P(3HB) was found to decrease by blending with atactic PVA when PVA was the predominant component of the blend. In P(3HB) blends with highly syndiotactic PVA, a significant suppression of P(3HB) crystallization was observed in a wider range of blend composition than that in P(3HB)/atactic PVA blends. These results are consistent with previous results obtained by means of solid-state C-13 nuclear magnetic resonance and differential scanning calorimetry. In blends with highly isotactic PVA, P(3HB) was found to crystallize in the same way as in pure P(3HB).