Fillers-carbon black and finely ground silica used to provide reinforcement
Oils, waxes, and fatty acids- used to improve processability.
Pigments-used to add coloring to the rubber.
The rubber specified for the M1Abrams tank is called carbon black masterbatch. A rough formula for this synthetic rubber is as follows.
Natural rubber: 57.21 percent.
Carbon black 31.14 percent.
Oil: 4.03 percent