Dielectric dispersion of polar polymers

A simple molecular theory is presented for the dielectric dispersion behavior of polar polymers. It is shown that the α dispersion involves movement of the chain backbone. The relaxation time for this dispersion is given by a relation of form τ α = a 2 f 0 /4 kt , where a , and f 0 are, respectively, the jump distance and friction factor for a chain segment. Although the numberical factor in this relation will depend somewhat on the exact model used for the computation, the general form of the relation is independent of the model as long as the chain can be considered a statistical coil. If the dipole is not rigidly attached to the chain backbone, a second, β dispersion region will result. The causes of the broadening of the dispersions are discussed.