ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The mechanical hysteresis of a polyether polyurethane thermoplastic elastomer was studied as a function of temperature, percent strain, and deformation energy. Hysteresis values remained small at low temperatures when the extent of the sample deformation did not disrupt the glassy matrix. This was readily evident at temperatures below the glass transition temperature, Tg of the polymer where the material did not formally yield. At temperatures above the Tg of the polymer, hysteresis remained small even at substantial strains levels and demonstrated the capabilities of the hard segment domains to act as physical crosslinks. At elevated temperatures, percent hysteresis increased as the hydrogen-bonded hard segment domains weakened. When mechanical hysteresis was considered on the basis of constant deformation energies, hysteresis values reached a maximum in the vicinity of the Tg of the polymer. These maxima existed as a consequence of two opposing trends: the decreasing resiliency of the polymer as it becomes a glass and the increase in the resistance of that glass to undergo deformations sufficient to cause plastic flow. Finally, a hysteresis response surface constructed as a function of deformation energy and temperature was found to be sensitive to both the strain-induced crystallization of the rubbery soft segment matrix and to the strain-induced yielding of the glassy soft segment matrix.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760331804
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