DIELECTRIC-RELAXATION OF POLY(TETRAFLUOROETHYLENE-PERFLUOROVINYL ETHER) FILMS

Dielectric constant and dielectric loss have been studied for poly(tet rafluoroethylene-perfluorovinyl ether) (PFA) films over a wide tempera ture range in the frequency range 0.1-100 kHz. Two relaxation peaks we re observed, one at room temperature (alpha(a)-relaxation) and the oth er in the range 170-140K (beta-relaxation), with activation energies o f 143.2 and 16.4 kcal/mol, respectively. The B-absorption is attribute d to the short segmental local mode motion of the main chains. The alp ha(a)-relaxation can be interpreted as due to large-scale conformation al rearrangement. The Cole-Cole diagrams are given at different temper atures and the distribution parameters (epsilon(0) - epsilon(infinity) ) and (1 - alpha) of the relaxation times were calculated. The X-ray d iffraction pattern of PFA shows both a diffuse halo and sharp reflecti ons, characteristic of amorphous and crystalline phases of conventiona l semicrystalline polymers. Also, no evidence of crystallinity in the films due to thermal treatment during dielectric measurements was obse rved. IR spectra revealed the absence of any new peaks after the heat treatment.