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Network characterization from stress–strain behavior at large extensions
Author(s) -
Morris M. C.
Publication year - 1964
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.1964.070080201
Subject(s) - natural rubber , isoprene , crystallization , extensibility , gaussian , materials science , stress (linguistics) , hysteresis , polymer science , range (aeronautics) , strain (injury) , thermodynamics , mathematics , polymer chemistry , composite material , chemistry , physics , polymer , computational chemistry , computer science , condensed matter physics , copolymer , linguistics , operating system , medicine , philosophy
The stress–strain properties of natural rubber and synthetic cis ‐polyisoprene vulcanizates have been investigated over a large range of extensions. The results are in qualitative agreement with those of Mullins, in that the upturn of a Mooney‐Rivlin plot is ascribed to finite extensibility effects. It is further found that the stress–strain curves can be adequately described by a modification of existing non‐Gaussian theory. Analysis of the curves shows significant finite extensibility effects even at extensions well below the upturn. Thus, division of stress–strain curves into Gaussian and non‐Gaussian regions is to be avoided. Values for n , the number of statistical segments between crosslinks, were calculated using the proposed treatment. The values of n found were relatively unaffected by temperature. Further, the molecular weight of a statistical segment was found to be about the same for synthetic cis ‐polyisoprene as for natural rubber despite differences in the crystallization behavior. Crystallization effects are therefore thought to be of little importance in determining the position of the upturn. The equivalent statistical segment was found to be 4.3 isoprene units for natural rubber and cis ‐polyisoprene.