DIPOLAR CORRELATION AND ACTIVATION-ENERGIES FOR THE SUBGLASS RELAXATIONS OF CHAINS WITH ASYMMETRIC SIDE-GROUPS

The effect of the location of the halogen atom on the distribution of activation energies associated with the subglass relaxation of poly(o- chlorophenyl acrylate) (POCPA) and poly(m-chlorophenyl acrylate) (PMCP A) is studied. Poly(p-chlorophenyl acrylate) (PPCPA) was also investig ated, though not in depth due to its low dielectric activity. The high temperature and frequency dependence found for the activation energy on the high temperature side of the subglass relaxations may not corre spond only to simple mechanisms associated with the P-process but also to more complex mechanisms associated with the glass-rubber relaxatio n. Dielectric activity arising from motions about O-C-ar bonds is resp onsible for the high dielectric strength exhibited by these polymers. Theoretical calculations based on the rotational isomeric state model are in fair agreement with the experimental relaxation strengths.