Diffusion characteristics of solvent toluene into nano calcium carbonate filled natural rubber composites

Solvent absorptions were studied in vulcanized rubber samples of widely varying amounts or nano calcium carbonate with a view to rate-limiting steps, the major diffusion rate control and other solvent properties. The surface resistance (the mass flux through the polymer surface, F-s) was found to affect the absorption process of the composites. The sorption results were interpreted by using first-order kinetic model. The S-shaped curvature clearly Indicates that solvent uptake process is significantly control by surface resistance in the present experiment. The h(ap) (the surface mass transfer coefficient) values for all the nano composite samples are always higher than the corresponding gum values. This indicates that time required for solvent molecules to get place on the composite sample surface is prominent. The B (the ratio of diffusional resistance and surface resistance) values ranging from 9 to 55, are not very high (i.e. <100), hence the surface resistance is important. The D-c, (diffusion coefficient corrected for free film exposed on two sides) value increases with filler loading. The comparable E-D (the activation energy of diffusion) values of gum and composites, expect good elastic properties in composites. The values of it (an idea about the mechanism of solvent transport) obtained for the different nano composites show anomalous (0.5 < n < 1.0) behaviour.