This research deals with the study the effect of adding the silica particles and
alumina particles separately with different ratio (5, 10, 15, 20, and 25 pphr) on the
hardness and wear rate of natural rubber NR and styrene butadiene rubber SBR. The
results show that the hardness increases with the increase the loading level of reinforcing
particles, while the wear rate decreases with the increase the loading level of the
reinforcing particles. The largest value of the hardness and the lowest value of the wear
rate were for styrene butadiene reinforced with 25 pphr of silica as compared with
natural rubber. Also the reinforcing by SiO2 increases the hardness and decreases the
wear rate more than of Al2O3.
The results indicated that the hardness and the wear rate for SBR and NR
reinforced by SiO2 and Al2O3 at (25 pphr) illustrated in the following table: