FT-IR Study of the Morphological Interactions in PHB/PAZO Blends and their Dependence on Solvent Variation

In this article, we demonstrate the vital role the solvent plays in influencing the resultant blend morphology in semi-crystalline PHB/PAZO blends. We will establish the relationship between the blend's FT-IR profiles and the morphology. We will also investigate the possible formation of a PHB/PAZO complex, previously reported.

PHB/PAZO blends were prepared in chloroform, acetone and toluene, chosen because of the similarity of their solubility parameter to that of amorphous PHB. The FT-IR spectral bands in PHB responsible for changes in morphology were observed in the 950-1350 cm⁻¹ region. These bands denote the amorphous band at 1185 cm⁻¹, the asymmetric C-O-C vibrations, the CH₂ wag and twist at 1231 cm⁻¹ and a crystal vibration at 1279 cm⁻¹. A series of less prominent bands sensitive to the crystalline and amorphous regions were also observed.

We deduced that penetration of PHB's crystalline shell by the solvent does occur and is crucial to complex formation and to blend miscibility.