Nanocomposite materials were obtained using glycerol plasticized starch as the matrix and a colloidal suspension of cellulose whiskers as the reinforcing phase. The cellulose whiskers, prepared from tunicin, consisted of slender parallelepiped rods with a high aspect ratio. After mixing the raw materials and gelatinization of starch, the resulting suspension was cast and evaporated under vacuum. The composites were conditioned at various moisture contents in order to evaluate the effect of this parameter on the composite structure. The resulting films were characterized using scanning electron microscopy, differential scanning calorimetry, water absorption experiments and wide angle X-ray scattering. An accumulation of plasticizer in the cellulose/amylopectin interfacial zones was evidenced. The specific behavior of amylopectin chains located near the interface in the presence of cellulose probably led to a transcrystallization phenomenon of amylopectin on cellulose whiskers surface.

In a previous work [Macromolecules 2000, 33, 8344], nanocomposite materials were obtained using glycerol plasticized starch as the matrix and a colloidal suspension of tunicinan animal cellulosewhiskers as the reinforcing phase. The mechanical behavior of resulting films was characterized in both the linear and the nonlinear range. The effects of the filler and water contents were evaluated, and the results were discussed on the basis of the knowledge of the structural morphology reported in the first part of the paper. The reinforcing effect of tunicin whiskers strongly depended on the ability of cellulose filler to form a rigid network, resulting from strong interactions between whiskers such as hydrogen bonds, and therefore on the moisture content. It was shown that increasing water content induced the crystallization of amylopectin chains and the accumulation of plasticizer in the cellulose/amylopectin interfacial zone. Both phenomena strongly interfere with hydrogen-bonding forces likely to hold the percolating tunicin whiskers network together.