Contributions of distinctive dynamic processes to dielectric response of a relaxorlike reduced poly(vinylidene fluoride-trifluoroethylene) copolymer

Dynamic processes in relaxorlike reduced poly (vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer have been studied by measurements of the temperature and frequency-dependent linear and third-order nonlinear dielectric response. Dielectric analysis of relaxor polymers has, namely, been incomplete until now, i.e., data interpretation was complicated by the fact that two similar types of dynamics, relaxorlike behavior in the crystalline part of the system and glass-to-rubber transition in the amorphous matrix, take place in the same temperature range and thus superimpose in the detected response. On the other hand, here, in the P(VDF-TrFE) system, synthesized via reductive dechlorination from the poly(vinylidene fluoride-chlorotrifluoroethylene), relaxor peaks take place at much higher temperatures, thus both dynamics can be investigated separately. Analysis of the experimental data reveals that the relaxorlike dielectric dynamics in the reduced P(VDF-TrFE) copolymer, which is now not influenced by processes in the amorphous matrix, indeed is almost identical to that observed in classical relaxor systems and, furthermore, reminiscent of the dynamic behavior observed in various spin glasses. Also, a clear indication was obtained that all polar dynamic processes terminate down to approximate to 100 K and that below this temperature only nonpolar contributions govern the dielectric response of the reduced P(VDF-TrFE) copolymer.