Agricultural Residues as Potential Diluents in Natural Rubber Formulation

Abstract

Agricultural residues such as Maize Husk, Groundnut Shell, Coconut Shell and Sugarcane Bagasse were collected, sorted, dried and ground to particulate fillers. The various fillers were characterized in terms of density, moisture content and pH value. Single ordinates of 150 µm particle size and 30 parts per hundred of rubber (pphr) loading were respectively adopted for all filler types. They were used alongside with conventional Sulphur vulcanization system (high Sulphur to low organo-accelerator level) in the formulations of natural rubber compounds. Tests such as tensile strength at 400% elongation, constant force compression set, abrasion resistance as a function of percentage mass retention on surface exposure to a rotating abrasive surface and thermal stability using differential scanning calorimeter were carried out. Results obtained revealed that rubber vulcanizate samples filled with coconut shell and sugarcane bagasse had hardness values of 58 and 57 on Shore A scale while unfilled vulcanizate and carbon black filled sample had respective values of 45 and 49 Shore A hardness. However, unfilled vulcanizate and carbon black filled vulcanizate showed superior values of tensile strength at 400% elongation to the ones filled with agricultural residues. Therefore, these agricultural residues can serve as diluents in the formulation of rubber vulcanizates.