Influence of solvent transport on physico-chemical properties of crosslinked butyl rubber filled with TiC ceramic

Understanding the vulcanization and swelling behavior of polymers is potentially important for composite materials, since vulcanization and swelling may significantly influence the electrical and mechanical properties. This work investigates the effect of TIC content on vulcanization reaction and on network structures like the characteristic time constant of vulcanization, vulcanization factor, volume fraction of rubber, extent of filler and interparticle distance between conductive particles. The crosslinking density of the rubber was calculated by the Flory-Rehner equation. The affine and phantom models for physical crosslinks were used to predict the nature of crosslinks. The experimental results were compared with the theoretical predictions. Sorption and diffusion of kerosene were investigated through butyl rubber (IIR) composites reinforced with different concentration of TiC ceramic. Effect of TiC concentration and temperature on solvent uptake and mechanism of diffusion were studied in detail and the experimental diffusion data compared with theoretical predictions. Concentration profiles of the kerosene were calculated to predict the applicability of these composites under extreme service conditions. The apparent activation energy of diffusion and some useful thermodynamic parameters like enthalpy, entropy, Gibbs free energy and heat of sorption were calculated. An abrupt increase in electrical resistivity appears after a characteristic time of swelling. Mechanical properties increase with the addition of TiC reinforcing filler, and decrease after swelling with kerosene (compared with that before swelling with kerosene). In conclusion, it was found that TiC improves the network structure and slows the diffusion of kerosene into the polymer by acting as a barrier. (C) 2001 Elsevier Science Ltd. All rights reserved.