PEEK constant stress rate
Constant stress rate tests on PEEK perfromed at different temperatures. It was used for further modelling of material behavior using neural networks
Steps to reproduce
Material: CENTROPEEK, Centroplast Engineering Plastics GmbH, Germany Sample geometry: 2 mm thick sheets machined into rectangular samples with dimensions 2 x 10 x 50 mm Conditioning/annealing: samples were annealed to remove residual stresses and avoid physical ageing during testing. Annealing was performed at 250 °C for 9 hours. Afterwards, samples were cooled to the ambient temperature with a cooling rate of 0,1 °C/min. Before measurement samples were additionally temperd at 130 °C for 5 h in the rheometer chamber. Thermal properties: DSC glass transition temperature: 153 °C, double melting peak. The first one, a smaller one at Tm1 = 264 °C (∆Hm1 = 8 J/g) and at Tm2 = 341 °C (∆Hm2 = 39,6 J/g). Degree of crystallinity of the samples was χ = 37 % (100% ∆Hm = 130 J/g). measurement temperatures, C: 130 140 145 150 155 160 165 170 180 190 200 Stress rate: 1000 Pa/s length of experiment: 300 s (maximal shear stress 0,3 MPa). number of measured data points: 1000 points number of repetitions: 3 - each one on new sample Protocol: 1 h of temperature stabilization, stress-strain measurement (300 s). After each loading, sample was unloaded (the applied moment on the sample was set to 0), and the temperature was raised. During the complete measuring procedure, the normal force was set to 0 N to prevent normal stresses in the sample because of thermal expansion or shear loading.