Okieimen¹, F. E.  and Imanah²*, J. E.
                                                               1.     Industrial Agricultural Products Research Laboratory,
                                                                       University of Benin, Benin City, Nigeria.
                                                               2.       Auchi Polytechnic, Department of Polymer Technology,
                                                                       Auchi, Edo State, Nigeria.
                                                                       E-mail: jeimanah @ yahoo. com. Tel: 08043139731.

Abstract

Natural rubber samples were filled with agricultural waste products (cocoa pod husks and rubber seed shell) at 0 – 100 phr, mixed on a two-roll mill and cured using the semi-efficient vulcanization system.  The scorch time, cure time and torque values of natural rubber compounds were determined at 185⁰C as a function of filler loading using Monsanto rheometer. The physico-mechanical properties: tensile strength, modulus at 100% elongation, elongation at break, hardness, abrasion resistance, flex fatigue and compression set of the vulcanizate natural rubber compounds were determined and compared with the values obtained for vulcanizates obtained with commercial carbon black (HAF N330).  The effect of blending the raw and carbonized agricultural waste products with the commercial grade N330 carbon black on the physico-mechanical properties of the natural rubber compounds was studied.  It was found that the raw agricultural waste products were ineffective compared with N330 carbon black as reinforcing filler for natural rubber compound mixes and could be classified as semi-reinforcing fillers.  Blends containing up to 40% by wt of the raw agricultural waste products and more than 60% by wt of the carbonized waste products gave natural rubber compounds with comparable physico-mechanical properties with compound obtained with N330 carbon black. Equilibrium swelling properties of the natural rubber vulcanizates in organic solvents; acetone and toluene, and hydrocarbon liquids, diesel and kerosene were determined and provided estimates of the dispersability of the particulate fillers derived from the agricultural by-products in the natural rubber matrix.

Keywords:         cocoa pod husk, rubber seed shell, fillers, natural rubber.