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 potent ially important for composite materials, since vulcanization and swelling m ay significantly influence the electrical and mechanical properties. This w ork 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 inte rparticle distance between conductive particles. The crosslinking density o f the rubber was calculated by the Flory-Rehner equation. The affine and ph antom models for physical crosslinks were used to predict the nature of cro sslinks. The experimental results were compared with the theoretical predic tions. Sorption and diffusion of kerosene were investigated through butyl r ubber (IIR) composites reinforced with different concentration of TiC ceram ic. Effect of TiC concentration and temperature on solvent uptake and mecha nism of diffusion were studied in detail and the experimental diffusion dat a compared with theoretical predictions. Concentration profiles of the kero sene were calculated to predict the applicability of these composites under extreme service conditions. The apparent activation energy of diffusion an d some useful thermodynamic parameters like enthalpy, entropy, Gibbs free e nergy and heat of sorption were calculated. An abrupt increase in electrica l resistivity appears after a characteristic time of swelling. Mechanical p roperties increase with the addition of TiC reinforcing filler, and decreas e after swelling with kerosene (compared with that before swelling with ker osene). In conclusion, it was found that TiC improves the network structure and slows the diffusion of kerosene into the polymer by acting as a barrie r. (C) 2001 Elsevier Science Ltd. All rights reserved.