Preparation and Evaluation of the Microstructure and Properties of Natural Rubber/Sodiummontmorillonite Nanocomposites

Natural rubber (NR)/sodium-montmorillonite (Na-MMT) nanocomposites were prepared by co-coagulating the mixture of NR latex and various amounts of Na- MMT aqueous suspension. Tapping mode AFM (for the first time in the present case), TEM and XRD were applied to characterize the structure of nanocomposites. Results showed that at the low loading of layered silicates, fully exfoliated structure could be achieved by this method. Both non-exfoliated (stacked layers) and exfoliated structures were observed in the nanocomposites when the amount of Na-MMT increased to 10 phr. The mechanical results on the vulcanized nanocomposites showed that nanocomposites present initial moduli and tensile strength greater than Na-MMTfreeNR compound. Furthermore, initial moduli increased with increasing the Na-MMT loading, indicating the reinforcement effect of Na-MMT on the mechanical properties of nanocomposites. The nanocomposites exhibit a higher glass transition temperature and lower tangent peak value in comparison with Na-MMT-free NR compound. TGA results indicated an improvement in the main and end decomposition temperature but there is no effect on the suppression of the initial decomposition temperature.