MODELING THE STRESS-STRAIN BEHAVIOR OF SHUNGITE PARTICLE-FILLED RUBBERS

摘要

Analytical modeling of mechanical behavior of elastomeric composite samples, filled with mineral ultradisperse particles of shungite, is performed in uniaxial tension. The composite matrix is assumed to be hyperelastic, while the polymer composites are elastic or absolutely stiff. The possibility of using different models in order to specify constitutive equations of a rubber hyperelastic matrix is analyzed. Two methods of averaging for determining effective properties of composites, the Mori-Tanaka method and the double inclusion method, are compared. To obtain an approximate estimate of mechanical characteristics of nanocomposites, we assumed that inclusions in the composite are surrounded by an interfacial layer (bounded rubber), the mechanical properties of which are similar to the properties of inclusions. The results of modeling are compared with the experimental data. Based on the comparison results we obtained an approximate estimate of the thickness of the interfacial layers formed around the reinforcing inclusions, which is 15-20 nm. This is a lower-bound estimate, since we do not take into account the nonlinearity of properties of the material of interphasial regions. Among the models discussed, the best approximation to the experimental data using the smallest number of material constants can be obtained by the Ogden model combined with the Mori-Tanaka method of averaging. It is shown that for composites with microsized inclusions, as well as in the case of nanocomposite strains up to 100%, we can use the hypothesis on the linearly elastic behavior of the material in the interfacial layers that are formed around the inclusions. However, in the case of high strains of materials with nanoinclusions it is necessary to take into account the nonlinearity of properties of the interphasial regions, the volume fraction of which is significant in this case.