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Determination of degree of crosslinking in natural rubber vulcanizates. Part IV. Stress‐strain behavior at large extensions
Author(s) -
Mullins L.
Publication year - 1959
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1959.070020601
Subject(s) - vulcanization , materials science , degree (music) , rubber elasticity , natural rubber , gaussian , swelling , elasticity (physics) , extension (predicate logic) , extensibility , stress–strain curve , composite material , thermodynamics , mathematics , computational chemistry , physics , computer science , chemistry , deformation (meteorology) , acoustics , programming language , operating system
Departures from behavior predicted by the statistical theory of rubberlike elasticity, which occur at high extensions, are ascribed to the finite extensibility of network chains. By use of a non‐Gaussian statistical theory, a relation is obtained between the extension ratio λ * , the extension at which departures are small but significant and the degree of crosslinking. Experimental results on the dependence of λ * on the degree of crosslinking and on the degree of swelling are in good agreement with theoretical predictions. It is shown that the additional determination of λ * permits the calculation of both the degree of crosslinking and the extent of network flaws due to chain ends, from a single simple extension stress‐strain curve. The calculation of these two basic parameters has hitherto been unattainable from measurements on vulcanized rubbers alone. This development provides a new technique of particular value in studies of the degradation of vulcanized networks.