Molecular transport of aromatic solvents through microcomposites of natural rubber (NR), carboxylated styrene butadiene rubber (XSBR) and their blends

Transport properties of aromatic solvents such as benzene, toluene and p-xylene through micron sized fillers reinforced natural rubber, carboxylated styrene butadiene rubber and their 70/30 blend latex membranes were investigated. The effect of penetrant size, filler loading and temperature on the diffusion properties were studied. The dispersion of filler in the matrix were analysed from scanning electron micrographs. Due to the lack of polymer/filler interaction aggregation of filler was higher in NR. The filled samples showed reduced swelling rate owing to the tortuosity of the path. A dramatic decrease in diffusion coefficient of filled samples was observed. However, blend system exhibited unexpected diffusion behaviour because of the immiscibility of the two components. The activation energies for diffusion of the penetrant were computed from the Arrhenius plots. The activation energy needed for diffusion of penetrant was found to be higher for filled virgin polymers. The transport mechanism was investigated and found that all systems exhibited non-Fickian anomalous behaviour. (c) 2006 Published by Elsevier Ltd.