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

Abstract

Abstract. 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.

Testing, Experiments and Properties of HSREP

“…Because this value is representative of values for glassy polymers [43], it is uncertain how much agreement can be improved by increasing m. In any event it is likely that increasing m will require changes in the relaxation model for deviatoric stresses as the relaxation of these stresses plays a major role in the determination of the transverse velocity-time profiles. Quantitative agreement with longitudinal wave arrivals is excellent over the full range of pressures (i.e., up to 18 GPa) used for reverberation experiments on thick samples.…”

Numerical modeling of non-woven fiber mats: Their effective mechanical and electrical properties

“…• Material parameters are taken from the literature [13,14], and the void space is assume to have 1:1000 of the solid modulus with Poisson's ratio 0.33.…”

Buckling of Polymer Matrix Composite Sandwich Infill Panels Under Different Thermal Environment

“…1 For this study, the PMC infill panel uses two types of closed-cell polymeric foam for the cores, which are Polyurethane (PU) and Polybutylene terephthalate (PBT). Tobushi [5] and Padini [7] have shown that the increase of temperature causes the reduction of characteristic parameter, such as elastic modulus, yield stress and Poisson's ratio of the polymer material, thus affects those of the polymeric foam. Gibson and Ashby [2] derived the prediction of relative Young's Modulus as function of relative density of foam as shown in equation (1) below:…”