Uniaxial tensile viscoelastic and viscoplastic behaviour of Nylon 12 at constant strain rate

Abstract

Tensile tests with constant crosshead speeds ranging from 5 to 200 mm min 21 were performed on Nylon 12 in the temperature range, 25 to 140uC. A modified form of the constitutive equations derived by Drozdov and Yuan were used to describe the time dependant response of Nylon 12 at isothermal deformation and small strains. Reasonable agreement was observed between the experimental data and the numerical calculations. A relationship between the materials constants derived for the uniaxial stress strain behaviour and temperature was found to exist. This is shown to satisfactorily calculate the constants required to accurately predict the stress strain behaviour of Nylon 12 at a specific strain rate and temperature.

Experimental and mathematical characterization of coronary polyamide-12 balloon catheter membranes

“…The induced stresses in the PA 12 membranes were found to be higher during dynamic equibiaxial testing above nominal pressure. The increase in the maximum stresses due to a higher strain-rate conforms with the findings of McFerran et al [20]. In the relaxation tests, the difference between the maximum stresses and the stresses after 200 s did not increase with a higher testing speed.…”

“…This conforms with the expectation that the 'Poisson Effect' would favor a stiffer reaction in biaxial extension. Compared to other tested polymers [30,31] and injection molded PA 12 [20], the processed balloon catheter membranes reveal a very stiff response…”

“…Every specimen got submerged for 15 min in 37˚C warm decalcified water to overcome hygroscopic and thermal changes inside the PA 12. These effects are well known from the literature [19,20], and might occur during a several minutes lasting coronary intervention. With the results from the VE ME 46-350 (Messphysik Materials Testing, Fürstenfeld, Austria) with a resolution of ±0.15 μm and a sample rate of f s = 20 Hz, the specimen stretches λ MD and λ CD…”