Relaxation Properties of Polyester-Based Polyurethane Under Small Deformations Superposed on Large Deformations
- 1 July 1969
- journal article
- Published by Society of Rheology in Transactions of the Society of Rheology
- Vol. 13 (2) , 193-208
- https://doi.org/10.1122/1.549159
Abstract
An investigation has been carried out to determine the extensional mechanical behavior of a viscoelastic material when it is subject to an infinitesimal displacement field superposed on a finite steady deformation. Experiments were conducted on a thin strip of a polyester‐based polyurethane at a temperature of 77°F (±3°F). It is shown that the relaxation modulus of this material can be expressed as a product of two functions, one of which depends only upon the elongation ratio and the other only upon time. This form is applicable for basic‐state elongation ratios 1⩽λ⩽1.2 and for a period of 2 hr. It is noted that the separable form is highly suspect for longer time intervals.Keywords
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