Theory of the dielectric constant and loss factor of long-chain paraffin derivatives

It has been assumed that the potential energy barrier hindering the rotation of chain molecules about their long axes in the solid state has one deep minimum and equation other minima with a potential energy V above that of the deeper well. Reasons are given for believing this approximates the true situation. Application of the Bragg-Williams approximation to this system, leads to the prediction of first-order thermal and dielectric transitions. The model indicates the existence of two Debye-type loss regions below the transition temperature, but only one above. It the molecules are regarded as rigid, the theory indicates (1) the entropy of transition, Rln equation, should be constant with chain length and (2) the transition temperatures of a homologous series should, rise linearly with increasing chain length. Data from the literature, dielectric constant, dielectric loss, and specific heat data on equation, equation and equation confirm the above predictions. Kirkwood's equation is used to calculate the static dielectric constants. Four different methods of obtaining equation indicate that it is close to 12. Reasons are given for believing that neither of the loss regions is of the pure resonance absorption type, and the sometimes extant belief that the dielectric and thermal effects at the melting and transition points of pure long-chain compounds are of the second order is criticized.