Starch Nanocomposites: Physico-Chemical Properties

NANCY LIS GARCÍA, ALAIN DUFRESNE, MIRTA ARANGUREN, SILVIA GOYANES

San Carlos de Bariloche, Argentina

Workshop; US-Argentina Workshop on nanomaterials; 2009

New nanocomposites were prepared using starch nanoparticles prepared by acid hydrolysis of waxy maize starch granules as the reinforcing phase. Cassava starch (28% de amylose, 72% amylopectin) or waxy maize starch (99% amylopectin) plasticized with glycerol were used as matrix. Both composites have shown important increases in the storage modulus value compared to that of the matrix. The incorporation of starch nanoparticles in a concentration as small as 2.5 wt% lead to increase the rubbery storage modulus in a 572 % for waxy and 380% for cassava starch. However, while the Cassava starch nanocomposite showed significant improvement in its water vapour permeability (decreasing by a factor of 40%), in the composite with Waxy starch as matrix the permeability increased significantly. The evaluation of the surfaces obtained by cryogenic fracture of the composites suggested that the nanoparticles are well dispersed, in the case of the Cassava nanocomposite, while in the case of the Waxy composite, the addition of nanoparticles lead to structures formed by agglomerates of "nano-fibers", probably due to associations of chains of amylopectin and/or agglomerates of nanoparticles.