Advances in Elastomers

Elastomer materials are characteristic for their high elongation and (entropy) elasticity, which makes them indispensable for widespread applications in various engineering areas, medical applications or consumer goods [...]

EXPERIMENTAL STUDY ON THE TEMPERATURE DEPENDENCE OF HYPERELASTIC BEHAVIOR OF TIRE RUBBERS UNDER MODERATE FINITE DEFORMATION

The hyperelastic behavior of unfilled natural rubber and some kinds of filled rubbers used in tire industry is tested by applying automated grid method. More accurate stress–strain data of tested rubber specimens at different temperatures are obtained. Test results show that different from the unfilled natural rubber whose stiffness increases linearly with temperature rising, the filled tire rubber has a tendency first to become soft and then to become stiff through its “critical temperature.” And this trend shift could be qualitatively interpreted by the joint action of two kinds of mechanisms, namely, the “energy elasticity” and the “entropy elasticity” effect. Besides, based on consideration of the relationship between model parameters and environmental temperature, the modified Arruda–Boyce model is extended to its explicit temperature-dependent form. Fitting results illustrate that this new model could take the temperature effect on hyperelastic behavior of tire rubbers into account well, and with an easy form, it is of convenient and practical usefulness in some relevant engineering application.

Nonlinear Fractional Derivative Models of Viscoelastic Impact Dynamics Based on Entropy Elasticity and Generalized Maxwell Law

Two types of models are proposed for describing nonlinear fractional derivative dynamical behavior of viscoelastic materials subject to impulse forces. The models are derived based on the thermodynamic elasticity in terms of entropy and on the “scale-free response of the material” under the basic assumption that the viscoelastic materials consist of stable coils of polymers, which we refer to as blobs. The blobs, which may be connected to each other by chemical bonds or physical bonds, are considered here as the elementary constituent of viscoelastic materials from which the nonlinear fractional derivative models are derived. Responses of individual blobs can determine the net collective response of the viscoelastic material to impulse forces. From the above consideration, two types of models are proposed in which the force elements or the stress elements are connected by the generalized Maxwell law.