The Effect of Partial Replacement of Paper Sludge by Commercial Fillers on Natural Rubber Composites

The effects of partial or complete replacement of two commercial fillers, carbon black (CB) and silica on cure characteristics, tensile properties, fatigue life, morphological properties, and rubber-filler interaction of paper sludge (PS) filled natural rubber composites were elucidated. Compounding was carried out on a two-roll mill with total filler loading of 30 phr. Results indicate that maximum torque, tensile strength, elongation at break, tensile modulus, and fatigue life increased the cure time while the scorch time decrease with increasing carbon black loading ratio of PS/CB filled natural rubber composites. On the other hand, increased loading of silica in PS/silica weight ratio resulted in an increment in cure time, scorch time, maximum torque, elongation at break, and fatigue life but not significantly altering tensile strength and tensile modulus of the natural rubber composites. In addition, PS/silica filled natural rubber composites exhibit lower maximum torque, tensile properties, and fatigue life compared to the PS/CB filled natural rubber composites. Rubber-filler interaction and SEM micrograph studies proved that the higher interaction between carbon black and natural rubber occurred in PS/CB filled natural rubber composites rather than PS/silica filled natural rubber composites.