Mechanical and electrical relaxation distribution functions of two compositions of polyvinyl chloride and dimethylthianthrene

Abstract

Dynamic mechanical and electrical data on two compositions of polyvinyl chloride and dimethylthianthrene, containing 10% and 40% polymer by volume, covering a wide range of frequencies and temperatures, have been treated by the method of reduced variables. The reduced real part of the complex compliance and the reduced mechanical loss tangent fall on single composite curves when the frequency scale is reduced by a temperature-dependent factor a T . The reduced real part of the dielectric constant and the reduced electrical loss tangent fall on single composite curves when the frequency scale is reduced by a temperature-dependent factor b T . The factors a T and b T are identical, but the mechanical and electrical composite curves are very different. The apparent activation energy for mechanical and electrical relaxation increases rapidly with decreasing temperature, and the values for the 10% polymer composition are not far from those for the apparent activation energy for viscous flow of the solvent. The frequency-dependent properties have been expressed as distribution functions of mechanical relaxation and retardation times and of electrical relaxation times. The mechanical relaxation distribution for the 10% composition is sharper and lies at shorter times than that for the 40% composition. The latter is similar in shape to distributions in the transition range between soft and glassy consistency for several other widely different polymer systems. The maximum in the mechanical retardation distribution is, for each composition, at a much longer time than the maximum in the electrical relaxation distribution, and the mechanical curves are much steeper on the short-time side of the maximum. It is concluded that the mechanical properties are strongly influenced by a distribution of effective chain lengths.