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Dynamic behavior of natural rubber during large extensions
Author(s) -
Harwood J. A. C.,
Schallamach A.
Publication year - 1967
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.1967.070111002
Subject(s) - elongation , materials science , viscoelasticity , natural rubber , superposition principle , crystallization , softening , composite material , stress (linguistics) , time–temperature superposition , mechanics , thermodynamics , mathematics , physics , mathematical analysis , ultimate tensile strength , linguistics , philosophy
The stresses and energy losses during simple extension cycles up to a maximum elongation of 530% have been determined for an unfilled vulcanizate of natural rubber as a function of the temperature and extension rate. At sufficiently short elongation times and low temperatures, the rate and temperature dependence of the ascending stresses are connected by the Ferry transform, and the superposition principle can be applied to them. Outside this experimental range, the stresses are increased by crystallization. The validity of the Ferry transform for the energy losses and the energy loss ratio is more restricted than for the stresses, and the losses are always higher than can be expected from a purely viscoelastic mechanism. The additional losses are tentatively ascribed to incipient crystallization and stress‐softening effects. At short elongation times and low temperatures, the losses approach the values predicted by viscoelasticity, and the loss ratio becomes independent of the maximum extension of the strain cycle.