Viscoelastic properties of composite materials with random structure

Abstract

A model for the structure of filled polymeric composites has been developed. To simulate filler-filler and filler-matrix interaction on a meso level, the Voronoi polyhedron representation of smallest structural elements (filler particles) is used while fractal concepts are applied for the description of more coarse-grained structures. An iterative method based on the ideas of renormalization group transformations is presented to calculate viscoelastic properties such as the storage and loss modulus of the composite. The influence of frequency as well as the properties of filler and matrix on the effective viscoelastic properties of polystyrene melt filled with glass spheres has been elucidated in a wide concentration range. The calculations and the experiments are in good agreement. Moreover, model calculations coincide with results of percolation theory.

Effective electrical conductivity of nanocomposites. Influence of image forces on contact conductivity of metal‐filled polymer nanocomposites

“…All these parameters characterize the percolation cluster in the vicinity of the percolation threshold X c (in our terms p c ). These parameters (the percolation threshold and critical indices) are universal characteristics, and only depend on the dimension of a space into which the percolation cluster is inserted [11, 13, 23, 26]. That is why, φ c in Eq .…”

“…That is why, φ c in Eq . 21 cannot be called the percolation threshold, because this value of φ c changes depending on the interaction of the filler particles with the polymer, i.e., it has its own value for each composite [23]. The parameter t in Eq .…”

“…The filled polymeric nanocomposite can be presented as a chaotic mixture of two sorts of polyhedron [23]: (1) polyhedron with the electrical conductivity σ k and (2) polyhedron with the electrical conductivity σ p , i.e., the electrical conductivity of a polymer. The effective electrical conductivity of a nanocomposite with chaotic structure σ can be defined with the help of the iterative averaging method (see ).…”

“…By using the calculation of the contact conductivity σ k , the calculations of the effective electrical conductivity σ of the filled polymer nanocomposites ER‐Cu, PVC‐Cu, ER‐Ni, and PVC‐Ni were carried out with the help of the iterative averaging method [23]. A comparison of the calculations and the experimental data shows their good agreement (Fig.…”

Dissipative Processes in Pvc Systems in Weak Electric Fields

“…In the case of an uncontrolled structure of the composite, Novikov [12] proposed a fractal model, by means of which an HPS is regarded as a mixture of polygons of two types of conductivity: contact conductivity:…”