Solvent-free synthesis, plasticization and compatibilization of cardanol grafted onto liquid isoprene rubber

Abstract Liquid isoprene rubber (LIR) is commonly used as plasticizer in rubber processing industry. It shows poor compatibility with inorganic fillers. Herein, cardanol grafted onto LIR (CA-g-LIR) was synthesized by solvent-free method and used as the dispersed matrix of silica particles. Results show that the optimum reactive condition is that 7 phr of cardanol monomer and 0.2 wt % of 2, 2-Azobisisobutyronitrile (AIBN) initiator per 100 g LIR react for 12 h at 70 °C. At these conditions, grafting ratio is 6.01%. CA-g-LIR shows obvious plasticizing effect, as is certified by its far high elongation at break (increase of 800%), decreased viscosity (reduction of 62%) and glass transition temperature (Tg, decline of 5.0 °C) compared with LIR. Moreover, CA-g-LIR shows good interfacial performance. The dispersion of silica particles in CA-g-LIR is better than that in LIR. CA-g-LIR is obtained by a simple and green way, low-cost, easy for industrial production. It is expected to be acted as plasticizer and compatibilizer at the same time in rubber industry.