Time and temperature effects on Poisson’s ratio of poly(butylene terephthalate)

• Format: Article
• Language: English
• Published: Budapest University of Technology 2011-08-01
• Series: eXPRESS Polymer Letters
• Subjects: Material testing; Mechanical properties; Viscoelasticity; Poisson s ratio
• Online Access: http://www.expresspolymlett.com/letolt.php?file=EPL-0002245&mi=cd

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.