Influence of Different Fillers on Natural Rubber Composites to Assess Mechanical Performance

Effect of different fillers on natural rubber compounds was investigated through curing, mechanical properties and morphology studies for improving mechanical performance of rubber articles. In this work, natural rubber blends with Silica as Single-filler compounds, and blends with Silica and Carbon black as Bi-filler compounds were considered. Then, natural rubber blends with Silica, Carbon black, and Waste Tyre Rubber (WTR) particles as Tri-filler compounds were synthesized by a two - roll mill in specified operating conditions. In addition, natural rubber vulcanizate was prepared by using the same process. The different proportions were presented in Bi and Tri-filler compounds (10, 20, 25, 30, 40 phr) on CB and CB-WTR respectively, whereas Silica was fixed at 20 phr. Curing characteristics showed that scorch time and optimum cure time significantly decreased with compared to natural rubber(NR) vulcanizate in all filler ranges. Whereas, minimum and maximum torque increased trend in all filler ranges. Cure rate index (CRI) also present and it showed significant good variation with the NR vulcanizate. Mechanical properties showed that tensile strength increased up to 30phr of CB in Bi-filler and it increased up to 10 phr with the addition of CB-WTR in Tri-filler compounds. Elongation at break decreased trend in Bi-filler and Tri-filler compounds, whereas maximum value was observed in single-filler compound. Hardness increased trend with addition of CB-WTR in Tri-filler, and it increased up to 25phr in Bi filler compounds. Tensile Modulus increased up to 25phr in Tri-filler and it increased trend in Bi-filler compounds. Tear strength increased up to 20phr and 25phr in Bi and Tri-fillers respectively. Morphological study showed that better filler dispersion and good interfacial adhesion by the natural rubber matrix increased the tensile strength and opposite in tear strength. Among the rubber materials tested, Bi-filler compounds were found to be more suitable for improving the mechanical performance in the rubber applications.