Modeling and experimental testing of the effect of solvent absorption on the electric properties of styrene butadiene rubber/carbon black chemical sensors

The results of a model, that describes the swelling and electric behavior of elastomer/carbon composites due to absorption of solvents, are comparing with experimental data in this work. The model takes into account the moving boundary problem present on the polymer swelling by solvents, solving it in a straightforward way using a Newton–Raphson technique. The experimental swelling behavior of the samples is very well described for the present model. It provides also a qualitatively proper description of the experimental electrical behavior of the samples during absorption of low polarity solvents. Even thought, it slightly underestimates the rate at which the sample's resistivity increases with the composite swelling (which could be due to a preferential diffusion of solvents into the elastomer/carbon interface); it has, however, the advantage to describe the involved phenomena in the correct direction.