Abstract
Nanocomposite materials of natural rubber (NR)/poly(ethylene-co-vinyl acetate) (EVA)/montmorillonite (MMT) were prepared by latex compounding without modification of the MMT. EVA and MMT were well mixed at room temperature in the latex state and subsequently blended with NR latex at NR/EVA dry weight ratios of 100/0, 90/10, 80/20, 70/30, 60/40 and 50/50. Where used, MMT was added at 4 parts per hundred of dry rubber and EVA (phr). The homogeneous latex mixture was then cast into sheets on a glass mold, air dried for 2 days at room temperature and then in an oven at 70 °C for 6 h. It was subsequently cured at 110 °C for 2 h. After curing, samples were examined for their structure and morphology by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), whilst tensile properties were investigated using a Universal Testing Machine. The XRD patterns and TEM images of the nanocomposites showed an exfoliated structure. The 90NR/10EVA/4MMT exhibited the highest tensile strength, with incorporation of MMT offering a substantial improvement in tensile strength. SEM micrographs revealed that the MMT particles were well dispersed in the polymer matrix. However, increasing the EVA content to 50 wt.% reduced the compatibility between NR and EVA.