ANALYSIS OF THE ELECTRIC RELAXATION IN ACRYLATE POLYMERS WITH RIGID SIDE-GROUPS

The curves describing the temperature dependence of the dielectric loss for poly(4-acryloxyphenyl)-(4-chlorophenyl)-methanone exhibit a well developed subglass absorption followed in order of increasing temperature by an ostensible glass-rubber relaxation or ct process. Free charge conductivity processes and blocking electrode phenomena become dominant in the Lu relaxation at frequencies below 10 Hz. An electric model is proposed to interpret the dielectric results covering the glassy state and the glass-rubber transition. The model is basically a parallel configuration involving a condenser (C-Gamma alpha), a resistance (R), and a Havriliak-Negami-type impedance (Z(HN)*) coupled in series with an impedance (Z(e)*) representing the electrode phenomena. The circuit allows one to split the dipolar processes from both free charges and blocking electrode conductivity contributions to the real epsilon' and loss epsilon'' parts of the complex dielectric permittivity at temperatures above the glass transition temperature of the polymer. At low frequencies the model predicts that epsilon' and epsilon'' scale with frequency as epsilon' similar to omega(-(1+<(alpha)over) (bar>)) and epsilon'' similar to omega(-<(alpha)over) (bar>), the exponent <(alpha)over bar> not being restricted to the conventional value of 0.5 commonly found in the literature. (C) 1995 American Institute of Physics.