Morphology, Barrier, Mechanical and Electrical Conductivity Properties of Oil-Extended EPDM/MWCNT Nanocomposites

Abstract

Oil- extended ethylene propylene diene monomer (EPDM) elastomer nanocomposites have been made by using multiwalled carbon nanotube (MWCNT) nanofiller as a reinforcing agent. The effect of MWCNT concentration on morphology, bound rubber, swelling, and mechanical properties have been studied. EPDM/MWCNT interactions have been studied by scanning electron microscopy (SEM) and highresolution transmission electron microscopy (HR-TEM) techniques. From the studies, it is observed that at lower MWCNT concentration (up to 4%), nanofillers are well separated and dispersed, but at higher loadings (6%) formation of agglomerates takes place. Hence it is expected that percolation limit of MWCNT in oil-extended EPDM occurs at around 4% concentration. The extent of reinforcement of MWCNT in EPDM matrix has been calculated in form of bound rubber (BdR) content and degree of swelling when exposed to solvents. BdR values of EPDM nanocomposites increase with MWCNT concentration hence confirmed the reinforcing nature of filler. Physico-mechanical properties like tensile strength, modulus and toughness of EPDM nanocomposites increases up to 4% MWCNT concentration, beyond which the effects are very marginal or decreases as filler-filler interactions exceed polymer-filler interactions. This confirmed the percolation threshold of MWCNT at 4% concentration. In addition to above, electrical conductivity of EPDM/MWCNT nanocomposites have been obtained as a function of frequency to measure the capability of a material to conduct electric current and it shows both frequency independent (DC) and dependent (AC) characteristic which increases exponentially in the applied field. AC conductivity of EPDM/MWCNT nanocomposites increases with filler concentration due to conductive nature of nanotube and a decrease in the mean free path of nanoparticles.