Time and temperature effects on Poisson’s ratio of poly(butylene terephthalate)
The viscoelastic nature of the Poisson’s ratio of a semicrystalline poly (butylene terephthalate) is highlighted by investigating its dependence on time, temperature and strain rate, under two types of loading conditions: i) constant deformation rate tests, in which the transverse strain i...
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| Format: | Article |
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| Language: | English |
| Published: |
Budapest University of Technology and Economics
2011-08-01
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| Series: | eXPRESS Polymer Letters |
| Subjects: | |
| Online Access: | http://www.expresspolymlett.com/letolt.php?file=EPL-0002245&mi=cd |
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| Summary: | The viscoelastic nature of the Poisson’s ratio of a semicrystalline poly (butylene terephthalate) is highlighted by investigating its dependence on time, temperature and strain rate, under two types of loading conditions: i) constant deformation rate tests, in which the transverse strain is measured in tensile ramps at various temperatures and at two strain rates; and ii) constant deformation tests, in which, under a constant axial deformation, the transverse strain is measured as a function of time in isothermal experiments performed at various temperatures. In both testing configurations, axial and transverse deformations are measured by means of a biaxial contact extensometer, and a correction procedure is adopted in order to compensate the lateral penetration of the extensometer knives. Poisson’s ratio displays the typical features of a retardation function, increasing with time and temperature, and decreasing with strain rate. This behaviour has been compared to that of simultaneously measured relaxation modulus. |
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| ISSN: | 1788-618X |