Blend films from chitosan and konjac glucomannan solutions

Blend films were prepared by blending 7 wt % konjac glucomannan (KGM) aqueo us solution with 2 wt % chitosan (CH) in acetate solution and dried at 40 d egrees C for 4 h to obtain the transparent films. Their structure and prope rties were studied by infrared (IR), wide-angle X-ray diffraction (WAXD), s canning electron microscopy (SEM), thermogravimetric analysis (TGA), and di fferential thermal analysis (DTA). Crystallinities of the blend films decre ased with the increase of konjac glucomannan. The thermostability, tensile strength, and breaking elongation of the blend films in dry state were obvi ously higher than those of both konjac glucomannan and chitosan films. Tens ile strength of the dry blend film achieved 73.0 MPa when the weight ratio of chitosan to konjac glucomannan was 7:3. The structure analysis indicated that there is a strong interaction between konjac glucomannan and chitosan resulted from intermolecular hydrogen bonds. The water solubility of the b lend films was improved by blending with konjac glucomannan, so they have p romising applications to soluble antiseptic coating of pills. (C) 2000 John Wiley & Sons, Inc.