Preparation of bio-based nanocomposite emulsions: Effect of clay type

Bio-based nanocomposite latexes were prepared by emulsification-diffusion method. Two kinds of silicate, sodium and organo-modified montmorillonites, were compared and clay concentrations were varied at 1-6 wt%. The resultant particles were characterized in terms of particle size, particle morphology, and zeta potential. Silicate dispersion in the polymer matrix was evaluated by X-ray diffractometry and transmission electron microscopy, while thermal properties of the resultant nanocomposite films were also investigated by differential scanning calorimetry and thermogravimetry. The average particle sizes of the emulsions were found in the range of 20-30 μm, whereas zeta potentials of the particles were obtained in the range from −37 to −60 mV, depending on the silicate type and content. X-ray diffraction patterns combined with micrographs indicated that the silicates were effectively distributed in the polymer matrix where extensive exfoliation and partial intercalation were present. Thermal properties of the nanocomposite films were significantly improved compared to those of the unfilled film. Thermal stability tended to increase in accordance with clay content for both types of silicate, in which the highest shift of degradation temperature was obtained with the sodium montmorillonite filled nanocomposite film at the maximum loading content (6 wt%).