Abstract

The study investigates the effect of incorporating three mesh sizes of ground tire rubber (GTR) at 10 parts per hundred of rubber (phr) and 20 phr loading in tire tread compound on its properties. The compounds were mixed in internal mixer using 40 rpm and 60 rpm rotor speed respectively. The viscosity, cure behavior mechanical properties and heat build-up of the rubber vulcanizates were studied. The base elastomer used for the production of the vulcanizate samples was NR/BR blend. Mixing was conducted using a two-step mixing technique. Results show that at 10 phr GTR loading, increased rotor speed resulted to reduced viscosity of the rubber compounds filled with 40, 60 and 80 mesh sizes of the GTR; while at 20 phr GTR loading, increased rotor speed resulted to increased viscosity of the compounds filled with 40 and 60 mesh size GTR, while the viscosity of the compound filled with 80 mesh size GTR reduced. The mixing torque was influenced by the amount of GTR incorporated in the rubber matrix as well as the mixing speed, but the varied particles sizes did not have much effect on the torque. The rotor speed and the temperature at which the curatives were added influenced the scorch and cure time among the samples filled with GTR thereby affecting the cure rate. Combination of results show that the properties of the samples mixed with 40 rpm rotor speed were better than those of the compounds mixed with 60 rpm rotor speed.