Temperature dependence of electrical conductivity for poly(vinyl chloride)-polyacetylene copolymer films

Abstract

The temperature dependence of the electrical conductivity for films of poly(vinyl chloride) whose macromolecules are crosslinked with chains of polyene conjugated bonds—the copolymer of vinylene and vinylchloride obtained as a result of the thermolysis of poly(vinyl chloride) in solution—is investigated. The experiments are performed for a series of samples 10 ± 1 μm in thickness, including pure poly(vinyl chloride) and copolymers with various concentrations of conjugated bonds, in the temperature range 15–85°C. At quite a high concentration of conjugated bonds, stepwise changes in conductivity of more than 10 orders of magnitude are observed. With an increase in temperature, the samples containing conjugated bonds transition from the state of low conductivity to the state of high conductivity. For the first time, it is found that the transition has a pronounced two-step character; i.e., between the extreme states of low conductivity (the sample resistance Rv > 1012 Ω) and high conductivity (Rv = 0.5 Ω), an intermediate quasistable semiconducting state with Rv = 104–105 Ω is registered. With an increase in the concentration of conjugated bonds, a tendency for the temperature transition—a jump in the electrical conductivity—to increase is observed. The contents of the conjugated bonds in the copolymer samples are evaluated according to the absorption spectra in the visible range.