Processing and properties of soy protein/silica nanocomposites fabricated in situ synthesis

Abstract

Nanocomposite materials were prepared via glycerol plasticized soy protein as the matrix and in situ fabricated silica as thereinforcing phase. The silica nanoparticles were synthesized in the protein environment by sodium silicate as a precursor. The resulting composites were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), tensile tests, and thermogravimetric analysis (TGA). The results revealed that silica particles were homogeneously dispersed in soy protein matrix at a nanometer scale with low silica addition (lower than 15%). Silica particles exhibited a high adhesion with protein matrix through hydrogen bonding and confined the motions of soy protein segments. The incorporation of silica as a reinforcing agent significantly improved the mechanical properties and thermal stability of soy protein plastics.