Determination of degree of crosslinking in natural rubber vulcanizates. Part III

Abstract

Abstract Improvement in methods of characterizing the stress‐strain properties of vulcanized rubber and of determining its molecular weight prior to vulcanization are described. Experimental results obtained previously by Mullins, Moore, and Watson, in an attempt to relate the physical properties of natural rubber to their network structure, are critically re‐examined to take account of these developments. It is shown that if empirical corrections are made for the effect of network flaws due to chain ends and for a second type of network defect equivalent to chain entanglements, then estimates of the degree of crosslinking derived from physical measurements and from chemical determinations are in remarkably close accord.