The results of experimental studies of conductivity anomalies in film samples of specially synthesized copolymer are analyzed, in which in PVC macromolecules the polyacetylene molecular fragments are embedded with a variable concentration. It has been experimentally established that spontaneous and stimulated conduction jumps occur in such samples by 13 orders of magnitude, and the life of each of these states can be very large from a few minutes to a day. In paper we propose a qualitative model describing the anomalous behavior of the conductivity of the PVC composite, comprising the mechanisms of stabilization of high conductivity state, the conditions of development of instability in the transitions between the states, as well as the reasons for long living state of high conductivity even when the applied voltage is switched off. Simple numerical estimates confirming the reality of the proposed mechanisms are also considered.
Several generalizations of the approximation of the effective Bruggeman medium using elliptic cells are compared, namely the “uniaxial” anisotropic approximation and two isotropic models averaged over random orientations and random conductivities of particles, allowing one to consider multicomponent composites with different filler particles.
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