Volume Change Measurements of Filled Rubber Vulcanizates under Stretching

The stretching dilatometer of our own design was manufactured, and, using it, we investigated the effects of the types of fillers, the amount of fillers, and the curing time on the volume change phenomena of filled rubber vulcanizates under elongation. It was found that the Δ υ /σ r (the volume increase induced by the strain divided by the real stress) as a function of γ (the strain) pattern of carbon black loaded rubber vulcanizates was greatly different from that of a whitetex loaded rubber vulcanizate. This phenomenon was explained in the viewpoint of the superposition of the first type and the second type cavitations which had been mentioned in the previous paper. It was found that the critical strain γ 0 is dependent upon the carbon black structures, and that the γ 0 value decreases while the Δ υ value increases with the amount of carbon blacks. It was also found that the Δ υ value increases while the Δ υ /σ r value decreases with curing.