INVESTIGATION INTO MORPHOLOGY, MICROSTRUCTURE AND PROPERTIES OF SBR/EPDM/ORGANO MONTMORILLONITE NANOCOMPOSITES

Rubber compounds based on styrene-butadiene rubber/ethylene propylene diene monomer blends of different compositions (60/40, 70/30, 80/20, 90/10, 100/0) reinforced with 1 wt%, 3 wt%, 5 wt% and 7 wt% organoclay (Cloisite 20A) were prepared on a two roll mill via a vulcanization process and characterized by several techniques. Results of X-ray diffraction showed expansion of the inter-gallery distance, and transmission electron microscopy (TEM) micrographs confirmed that the prepared nanocomposite samples have intercalated and partially exfoliated structures. Cure characteristics showed that, organoclay not only accelerates the vulcanization reaction, but also gives rise to a marked increase of the torque, indicating crosslink density of the prepared compounds increases at the presence of organoclay. Mechanical properties of samples received markedly increase by clay loading due to the good interaction established between nanoclay particles and polymer matrix as it was evidenced by SEM photomicrographs. At the same time, rheological properties showed that addition of nanoclay could improve storage modulus as well as complex viscosity of SBR/EPDM samples. The results of ozone test revealed that the ozone resistance of samples significantly increases as nanoclay or EPDM content increases.