Experimental viscoelastic properties evaluation, under impact loads and large strain conditions, of coated & uncoated rubber from end-of-life tires

Abstract

End-of-life tires (ELTs) pose a serious environmental problem today due to their great ability to maintain their properties and not degrade under extreme conditions or over time. One of the ways to reuse this material is to subject it to a recovery process to obtain new raw materials that can be used as convenient. This article focuses on the nonlinear viscoelastic properties characterization of the rubber obtained by the Danish company genan®. This company has developed a manufacturing process that, via exothermic reactions, gives a renewed rubber (in form of cylinders, called pellets later on) with improved viscoelastic properties in comparison with the starting material. These pellets, with the help of a binder to form an agglomerate, are currently used in some applications to reduce the effects of accidental impacts, like, for instance, in floors of playground areas or similar applications. However, a rigorous characterization of this material has not been done still now. With this goal, a compression impact test is carried out using different impact velocities, namely, different strain rate, which remain constant during the test. Based on the tests’ results the material behavior is adjusted into a Bergström– Boyce viscoelastic model. The shape and dimensions of the specimens, non-modifiable because they depend on the manufacturing process, establish strong limitations to the experimental study, which have been successfully overcome. This work is the first step to evaluate, numerically, systems designed to absorb impact loads based on this recycled material. Task in which the authors of this work are involved nowadays to prove, in a near future, that this material can be reused in passive energy dissipation systems, contributing, at the same time, to palliate environment and safety road problems. For that reason, the energy scattering ability of this material is, also, experimentally evaluated.