Abstract
The results of tensile stress-strain, stress relaxation, swelling, electric conductivity, and power factor tests show that the properties of pure vulcanizates are only slightly affected by previous stretching or flexing; on the other hand, the properties of vulcanizates containing reinforcing agents, or fillers which stiffen the rubber, may be considerably changed by previous stretching. The increases of stiffness, electric conductivity, and power factor produced by the incorporation of the fillers are destroyed by flexing or stretching. From most practical points of view these changes are of a permanent nature, as at normal temperatures the recovery towards the initial properties is slow. These effects are attributed to the breakdown of both agglomerates and chains of filler particles, and the adsorption of the filler particles on the rubber.
