Crystallization behavior and environmental biodegradability of the blend films of poly(3-hydroxybutyric acid) with chitin and chitosan

Crystallization behavior and environmental biodegradability were investigated for the films of bacterial poly(3-hydroxybutyric acid) (PHB) blends with chitin and chitosan. The blend films showed X-ray diffractive peaks that arose from the PHB crystalline component. It was suggested that the lamellar thickness of the PHB crystalline component in the blends was large enough to show detectable X-ray diffractive peaks, but this was too small to show observable melting endotherm in the DSC thermogram and the crystalline band absorption in the FT-IR spectrum. In the PHB/chitin and PHB/chitosan blends, thermal transition temperatures of PHB amorphous region observed by dynamic mechanical thermal analysis were almost the same as that of neat PHB. Both the PHB/chitin and the PHB/chitosan blend films biodegraded in an environmental medium. Several blend films showed faster biodegradation than the pure-state component polymers.