PVA NANOCOMPOSITES OF ORGANOCLAYS OBTAINED USING DIFFERENT CATIONIC SURFACTANTS

Abstract

This study is about the preparation of two different organoclays with cationicsurfactants and their poly(vinyl alcohol) nanocomposites with increased thermal andmechanical behavior. Organoclays were prepared to modify clay mineral with solutionintercalation method using aqueous solutions of cationic surfactantsdodecyltrimethylammonium 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. Resultsindicated an absolute decrease in zeta potential about 20 mV for C-MMT and 14 mV forD-MMT indicating flocculation and coating of the surface. Moreover, measurementsindicated that interlayer distance increased based on basal spacing peak shift whosevalue 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; thermalstability of the nanocomposites was determined using TGA, while mechanical strengthmeasurements were done using DMA. The maximum thermal decomposition temperatureof the pristine PVA and nanocomposites were compared, and an average increase of 4°Cwas observed. Also, the activation energy of the decomposition was observed ca. 40kJ.mol-1 higher than pristine PVA.