Carbon black's effects on vibration isolation

Dynamic properties of compounds containing wide ranges of carbon black types and loadings were shown to be well represented on a k_d/k_s vs. tan δ curve by a single exponential curve. In compounds with a single kind of elastomer, changes in carbon black type or loading facilitate movement up or down the k_d/k_s vs. tan δ curve but not off of it. Moving off the curve could be accomplished by changing the elastomer used in the rubber formulation to one of higher or lower hysteresis depending on the desired direction. Carbon blacks with aggregate size distributions of differing widths were found to have little effect on the k_d/k_s ratio (or on tan δ) in a natural rubber compound. Carbon blacks with higher surface areas were found to provide higher tear strengths of rubber compounds, as expected. It was further shown that improved tear properties with equivalent dynamic performance could be achieved by using lower loadings of a more highly reinforcing carbon black in both natural rubber and butyl rubber compounds. Adding oil to a carbon black loaded natural rubber compound, either during mixing or by swelling it into the vulcanizate, reduced the G_s of the compound. When the oil is added by swelling it into the vulcanizate, however, a reduction in the tan δ of the compound is also observed.