Modification of Sodium Montmorillonite: Dependence of Silylation on Premixing Process

Organic modification of hydrophilic sodium montmorillonite (Na+-MMT) is important for improving its compatibility with organic polymers. In the present research, (3-aminopropyl)triethoxysilane (APTES) was used to modify Na+-MMT. The effects on the basal spacing of Na+-MMT upon the premixing process with different mixing techniques were examined in detail. The resultant products (S-Mts) were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. For monitoring the grafting process, FTIR was used, while the percentage of the loaded silane was calculated using TGA. Furthermore, XRD measurements were carried out to evaluate the increase in the d-spacing. The amount of grafted silane increases when a suitable premixing process, such as the mechanical mixer and homogenizer, is chosen. The same beneficial effects were observed on d-spacing, as it increases when using the mechanical mixer and homogenizer. This study demonstrates that the degree of grafting and d-spacing of the grafted products strongly depends on the mixing process before the silylation reaction. This is very important for the synthesis and application of polymer nanocomposites containing silylated layered silicate minerals.