Effect of replacing carbon black with surfactant-modified silica clay on mechanical properties of natural rubber composites

The effect of replacing carbon black (CB) with surfactant-modified silica clay (SMSC) on hardness and tensile properties of natural rubber (NR) composites was studied using a simplex-lattice design of experiment. SMSC was produced by treating silica clay (SC) with coconut diethanolamine (CDEA) and glycerol monostearate (GMS). Complete replacement of CB with SMSC resulted in the decrease of Shore A hardness and tensile stress at all elongations. At higher CB to SMSC ratio, SMSC modified with CDEA performed better than with GMS. However, at lower CB to SMSC ratio, GMS exhibited larger values in the mechanical properties of NR composites. This can be attributed to the surface morphologies of SMSC and the surface aggregation of surfactant to SC. (paper)