Structural changes and their effect on mechanical properties of silk fibroin/chitosan blends

Silk fibroin/chitosan blend films were prepared by the solvent casting meth od. Miscibility between silk fibroin and chitosan was examined by dynamic m echanical thermal analysis. Structural changes of silk fibroin by the addit ion of chitosan were investigated by IR spectroscopy. The conformational tr ansition of silk fibroin from random coil form to beta-sheet structure indu ced by blending with chitosan resulted in the increase of crystallinity and density of the blend films. The blend film containing 30 wt % chitosan exh ibited a maximum increase in crystallinity and density. It was found that t he tensile strength and initial tensile modulus of blend films were greatly enhanced with increasing the chitosan content and showed a maximum value a t the composition of 30 wt % chitosan. (C) 1999 John Wiley & Sons, Inc.