PVA nanocomposites of organoclays obtained using different cationic surfactants

This study is about the preparation of two different organoclays with cationic surfactants and their poly(vinyl alcohol) nanocomposites with increased thermal and mechanical behavior. Organoclays were prepared to modify clay mineral with solution intercalation method using aqueous solutions of cationic surfactants dodecyltrimethylammonium bromide (DTABr) and cetylpyridinium bromide (CPBr). Obtained organoclays (D-MMT and C-MMT for DTABr/MMT and CPBr/MMT, respectively) were characterized using different methods including zeta potential and XRD. Results indicated an absolute decrease in zeta potential about 20 mV for C-MMT and 14 mV for D-MMT indicating flocculation and coating of the surface. Moreover, measurements indicated that interlayer distance increased based on basal spacing peak shift whose value was 1.27 nm for NaMMT, whereas 1.40 nm for D-MMT, and 1.75 nm for C-MMT. The organoclays were used in the preparation of PVA/clay nanocomposites; thermal stability of the nanocomposites was determined using TGA, while mechanical strength measurements were done using DMA. The maximum thermal decomposition temperature of the pristine PVA and nanocomposites were compared, and an average increase of 4°C was observed. Also, the activation energy of the decomposition was observed ca. 40 kJ.mol^-1 higher than pristine PVA.