Abstract
Stability of network structure was discussed. ESR measurements under the tensile elongation of vulcanizates gave us useful information on the changes of network structure during tensile elongation. ESR spectra showed the appearance of carbon and sulfur radicals which were produced by the breakdown of chemical linkages in the network structure. At a given mechanical energy applied to the vulcanizates, the radical concentration was dependent on the style of network structure and chemical structure of rubber molecules. The difference of binding energy in the network structure was not enough to explain the results. A stress concentration which was induced by the inhomogeneous network structure might have an important role on the partial destruction of network structure in the vulcanizates.
