| This work focused on examining and characterizing the reinforcement of thermoset and thermoplastic elastomers, such as natural rubber, epoxidized natural rubber and elastomeric polypropylene. The reinforcement was achieved through the formation of composites of these elastomers with reinforcing fillers by applying some of the latest techniques.; One of the techniques is the combination of elastomeric materials with thermosetting resins, specifically natural rubber and cardanol-formaldehyde resins, to improve mechanical properties, such as toughness and thermal properties, such as high-temperature resistance. The natural product cashew nut shell liquid was used to obtain the cardanol, which was then used to prepare cardanol-formaldehyde (CF) resole and novolak resins. The curing behavior of systems containing natural rubber and cardanol-formaldehyde resins was established. The incorporation of cardanol-formaldehyde resins into natural rubber provided significant improvements in tensile strength, while maintaining the thermal stability of the elastomer. Various nanocomposites of epoxidized natural rubber, cis-1,4 polyisoprene and elastomeric polypropylene were successfully prepared by using montmorillonite clays as a reinforcing filler. Conditions were established for dispersing clay nanolayers into these elastomers. The clay filler-elastomer and clay filler-filler interactions were studied by using dynamic mechanical analysis. Such interactions were found to strongly depend on the clay organic modifiers and the polarity of the elastomers was found to have a major effect on the final properties of these nanocomposites. The dispersion of clay fillers into the elastomer matrix was examined by X-ray diffraction techniques. Mechanical property measurements showed that several organo-clays provided very strong reinforcing effects. For non-polar elastomers, organo-modified clays were found to behave more like “carbon black”. For polar elastomers, the intercalation of the elastomeric chains into the clays or modified clays increased the filler volume, and thus increased the networking effect.; The catalytic selectivity of colloidal palladium nanoparticles immobilized by various water soluble polymers was examined. It was found that immobilized colloidal catalysts showed high selectivity in the hydrogenation of cyclic and non-cyclic olefin molecules. Low selectivity was observed in the hydrogenation of iso-olefins with different sizes, or olefins having the double bond in different positions. However, selectivity was promoted and enhanced by increased loading of immobilizing polymers. The particle size and particle size distribution of the palladium colloids were determined by transmission electron microscopy (TEM), while the morphology was investigated by small angle X-ray scattering (SAXS). |
