A study of the elastoplastic properties of polymer-silicate nanocomposites with allowance for the change in their volumes during deformation

• Published in: Polymer science. Series A, Chemistry, physics Chemistry, physics, 2011-12, Vol.53 (12), p.1187-1197
• Main Authors: Garishin, O. K., Gerasin, V. A., Guseva, M. A.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Deformation; Elastoplasticity; Fillers; Mathematical analysis; Mathematical models; Nanocomposites; Polyethylenes; Polymer Mechanics; Polymer Sciences; Tensors
• ISSN: 0965-545X; 1757-1820; 1555-6107
• DOI: 10.1134/S0965545X11120042

The results of experimental and theoretical studies of the elastoplastic properties of medium-density polyethylene and nanocomposites formed on its basis with a filler of layered clay minerals are described. It is found that the deformation of these materials is accompanied by a significant change in their volumes, which is primarily caused by the development of internal damage of the system (the formation of pores and cracks at the microlevel). A component that takes into account the change in volume during deformation is introduced into the previously proposed model of a heterogeneous medium that can undergo significant non-linear elastic and plastic deformations. For this purpose, we use a differential approach to the construction of constitutive equations and an additive decomposition of the total strain-rate tensor of the medium into strainrate tensors of the elastic and plastic components. Using an improved model, we describe the experimental curves of uniaxial stretching for pure PE and two PE-based polymer-silicate nanocomposites. The introduction of filler particles into the polymer matrix leads to enhancement of the role of two structural mechanisms in the formation of plastic properties: The presence of the filler contributes to the development of internal structural damage; the same particles decrease the orientation ability of the PE matrix, thereby hindering the development of plastic deformations in it. The use of tensor variables in the model makes it appropriate for describing not only stretching but also other types of loading of the material.