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

Crystallization behavior and environmental biodegradability were investigat ed for the films of bacterial poly(3-hydroxybutyric acid) (PHB) blends with chitin and chitosan. The blend films showed X-ray diffractive peaks that a rose 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 blend s, thermal transition temperatures of PHB amorphous region observed by dyna mic mechanical thermal analysis were almost the same as that of neat PHB. B oth the PHB/chitin and the PHB/chitosan blend films biodegraded in an envir onmental medium. Several blend films showed faster biodegradation than the pure-state component polymers. (C) 2000 Elsevier Science Ltd. All rights re served.