Synthesis and characterization of clay nanocomposites based on starch

Abstract

ABSTRACTIn this work, the synthesis of starch-clay nanocomposites was carried out. For this purpose, natural starch was extracted from rice grains and it was characterized by structural and spectrophotometric techniques. Afterwards, it was used as the polymer matrix for the synthesis of nanocomposites crosslinked with different agents: glycerol, citric acid (CA) and sodium trimetaphosphate (STMP). As a reinforcement phase, a natural Mexican clay from the Montmorillonite-type (Mt), was employed, which was modified with a cationic surfactant, hexadecyltrimethylammonium bromide (HDTMA-Br), in order to exchange cations, present in the interlaminar spaces of the raw clay mineral with those of the cationic surfactant; thus, changing its nature from hydrophilic to hydrophobic. Characterization, of both natural and organo-modified clays, was carried out by means of scanning electron microscopy (SEM), to determine the change in morphology between these two minerals; X-ray diffraction analysis (XRD), to obtain the crystalline structure of the organo-modified clay and that of the raw clay mineral (Mt). Also, the Fourier transform infrared spectroscopy (FTIR) was employed to determine materials spectra, and their thermal stability was evaluated by means of the thermogravimetric analysis (TGA). On the other hand, the synthesis of these nanocomposites was performed using different crosslinking agents, glycerol, CA or STMP, in order to identify the effect of them into the final properties of these materials.