The effect of silica on the properties of marble sludge filled hybrid natural rubber composites

Hybridization of natural rubber (NR) filled marble sludge (MS) and silica composite was prepared by adding various weight ratios of MS and silica. Compounding was carried out on a two-roll mill with total filler loading of 60 parts per 100 rubbers (phr). The composites were vulcanized at 140 °C. The effects of partial or complete replacement of MS with silica on physical characterization such as curing characteristics, mechanical and swelling parameters of composites were examined. Mechanical properties of composites, including tensile strength, elongation, modulus, tear strength, hardness, swelling parameters such as swelling ratio, volume fraction, crosslink density and shear modulus before and after aging, were analyzed. Results indicate that minimum torque, maximum torque, tensile strength, modulus, tear strength, hardness, and crosslink density volume fraction increased while elongation at break, swelling ratio and shear modulus decreased with the increasing silica loading in MS/NR/Silica hybrid composites. The aging test of corresponding hybrid composites was also evaluated at two different aging temperatures. The results in this work recommend that MS from marble processing industrial waste could be used as filler for cost savings in NR compounds.