Thermoplastic cassava starch-waxy maize starch nanocrystals nanocomposites

Abstract

The present study investigated the effects of adding maize starch nanocrystals on the physical and mechanical properties of thermoplastic cassava starch films. Waxy maize starch nanocrystals obtained by hydrolysis of native granules were used as a reinforcing agent in a thermoplastic cassava starch matrix plasticized with glycerol. The addition of nanocrystals slightly reduces the thermal resistance of the composites, as suggested by the shift to lower temperatures of the thermo-gravimetric curve (TG). Dynamic mechanical analysis (DMA) showed that the rubbery storage modulus (measured at 50°C) of the nanocrystal composites is about 4 times the modulus of the unfilled polymer. It was shown that the reinforcing effect of starch nanocrystals could be attributed to filler/matrix interactions due to the establishment of hydrogen bonding.