Dielectric anisotropy in oriented poly(chlorotrifluoroethylene)

Dielectric measurements between −50 and 60°C have been made on isotropic and oriented samples of poly(chlorotrifluoroethylene) with draw ratios λ of 1 to 3.5 at frequencies ranging from 30 Hz to 1 MHz. For the oriented samples, the dielectric loss has been measured with the electric field normal (ε ) and parallel (ε ) to the draw direction. At low frequency (say 60 Hz) the loss data for the oriented samples reveal two peaks at 25 and −5°C, which are associated with the amorphous (γ a ) and the crystalline (γ c ) relaxations, respectively. Analysis of these data using a two‐phase model yields values for the amorphous orientation function f a which are only about 25 to 60% of those for the crystalline orientation function f c . Upon annealing, the anisotropy ε /ε at the γ a peak decreases significantly while that at the γ c peak remains largely unchanged. This implies a roughly unaltered f c and a large decrease in f a , which is consistent with the results of wide‐angle x‐ray diffraction and birefringence measurements.