No abstract

No abstract

The eight-chain model, also known as ArrudaBoyce model, is widely used to capture the rate-independent hyperelastic response of rubber-like materials. The parameters of this model are physically based and explained from micromechanics of chain molecules. Despite its excellent performance with only two material parameters to capture bench measurements in uniaxial and pure shear regime, the model is known to be significantly deficient in predicting the equibiaxial data. To ameliorate such drawback, over the years, several modified versions of this successful model have been proposed in the literature. The so-called full-network model is another micromechanically motivated chain model, which has also few modified versions in the literature. For this study, two modified versions of the full-network model have been selected. In this contribution, five modified versions of the Arruda-Boyce model and two modified versions of full-network model are critically compared with the classical eight-chain model for their adequacy in representing equibiaxial data. To do a comparison of all selected models in reproducing the well-known Treloar data, the analytical expressions for the three homogeneous deformation modes, that is, uniaxial tension, equibiaxial tension, and pure shear have been derived and the performances of the selected models are analysed. The comparative study demonstrates that modified Flory-Erman model, Gornet-Desmorat (GD) model, Meissner-Matějka model, and bootstrapped eight-chain model predict well the three deformation modes compare to the classical eight-chain model.

No abstract

No abstract

No abstract

The influence of the temperature history on the Mullins effect, its recovery behaviour and the rate dependence is experimentally investigated using NR/BR (NR: natural rubber, BR: polybutadiene rubber) rubber blend. The crystallization which occurs in rubber during long term storage below the melting temperature has been taken into account to interpret the experimental data. To study the influence of low temperatures and large deformations on the Mullins effect, cyclic strain‐controlled processes are applied under different temperatures. The softened specimens are subjected to a sequence of heating, cooling, and conditioning processes in order to study the influence of the temperature history on healing, melting, and recrystallization. The results indicate the existence of a threshold temperature: if the specimen temperature is larger than this threshold, a nearly complete recovery of the material occurs within finite time, while any temperature below this limit will be too small for healing. The temperature dependence of both the healing and the Mullins effect in rubber with different degrees of crystallinity is resolved by considering the melting and recrystallization rates. The rate dependence of the blend is investigated under different temperatures via monotonic and cyclic tension tests at different strain rates and relaxation tests. The experimental data suggests a decrease in the strain rate sensitivity at higher temperatures.

No abstract