Morphology, phase continuity and mechanical behaviour of polyamide 6 chitosan blends

Blends of chitosan with polyamide 6 (PA6) were prepared via the solution casting technique using formic acid as a common solvent. The morphology and the mechanical behaviour of films with chitosan concentrations ranging from 15% to 70% (w/w) were investigated by scanning electron microscopy and dynamic mechanical analysis. Assuming an hypothesis about blend morphology, the mechanical behaviour of the materials was predicted from various models involving the percolation concept. From comparison between experimental and predicted data it is concluded that the chitosan phase tends to sediment and to form a continuous phase on the lower face of the film, if the chitosan content is high enough. This continuous phase is bristling with chitosan domain cones, which can emerge on the upper face of the film depending on the blend composition. The PA6 rich domains fill the upper face of the sample. (C) 1999 Elsevier Science Ltd. All rights reserved.