OXIDATIVE AGING OF NATURAL RUBBER VULCANIZATES.3. CROSSLINK SCISSION IN MONOSULFIDIC NETWORKS

A natural rubber vulcanizate containing almost entirely monosulfidic crosslinks was oxidized in oxygen and with tert‐butyl hydroperoxide. The changes in physical properties due to oxidation were followed by stress–strain measurements, and the changes in chemical structure were investigated with chemical probes, and by spectroscopic methods. The results show that when the oxidized vulcanizates are heated at 75°C., the monosulfidic crosslinks are broken, that crosslinks containing two sulfur atoms are formed, and that conjugated diene and triene structures are introduced into the main polyisoprene chains. Copyright © 1968 John Wiley & Sons, Inc.