Preparation and characteristics of beta-chitin and poly(vinyl alcohol) blend

Mechanical properties of blend films of beta-chitin and poly(vinyl alcohol) (PVA) in dry and wet states were improved compared to those of homopolymers. Fourier transformed infra-red (FT i.r.) spectra of the blend showed the transition of hydroxyl and carbonyl stretching bands upon blending. The subtraction infra-red spectra of blend 70/30 indicated that the blend showed an intermolecular interaction and the reduction of crystallinity compared with those of pure beta-chitin. Wide angle X-ray diffraction (WAXD) patterns of the blend also exhibited the loss of crystallinity of beta-chitin and PVA upon blending. The blends, however, showed a mixed-crystal structure. Dielectric analysis of the blend showed the transition of alpha- and beta-relaxation peaks of beta-chitin upon blending, appeared at 182 degrees C and 97 degrees C, respectively. For blends, the temperature of the maximum loss (T-max) of beta-chitin appeared at around 182 degrees C shifted to a lower temperature region. Differential scanning calorimetric analysis of the blend also showed the transition of melting endotherms of the blend. Transmission electron microscope (TEM) studies of blends using ruthenium tetraoxide as a staining agent were examined to reveal the micro-structure and miscibility of the blends. The TEM micrograph of blend 70/30 shows some microseparations, but it is still believed to be miscible in the blends. Copyright (C) 1996 Elsevier Science Ltd.