We investigated the validity of the fluctuation dissipation theorem in the structural glass former triphenylolmethane
triglycidyl ether. Polarization relaxation measurements were compared to the thermal fluctuation of the polarization. We
observed that above the glass transition temperature, the fluctuation dissipation theorem is fully verified, whereas below
the glass transition temperature the power noise spectrum measured subsequently to a temperature quench is more
intense than that expected from response measurements. The amplitude of the fluctuation is distributed according to a
non Gaussian distribution, whose origin is not strictly related to the presence of intense noise pulses.
KEYWORDS: Polymers, Dielectrics, Temperature metrology, Solids, Data modeling, Doping, Dielectric polarization, Systems modeling, Chemical reactions, Macromolecules
The conducting polymer poly(3n-decylprrole) (P3DP) has a promising chemical stability and processability. The long alkylic chains makes P3DP soluble in common organic solvents even if they partially hinder a regular molecular arrangement. On account of structural disorder, the materials has a moderate conductivity despite the high doping level. The d.c. conductivity and the dielectric response of P3DP films with different dopants and synthesis conditions were measured at temperatures between 80 and 300 K. The d.c. conductivity of all the samples was well described by the variable range hopping model; the hopping parameters were found to be much affected by the synthesis and doping conditions. The electrical response exhibited a well-defined relaxation peak, visible only after deducting the d.c. conductivity contribution from the loss factor. The temperature behavior of the loss peak frequency parallelled that of the d.c. conductivity. The Barton-Nakajima-Namikawa equation, relating d.c. conductivity, relaxation time and relaxation strength, was verified. The relaxation strength, too large for being connected with a dipolar relaxation, was ascribed to the displacement of hoping charges. The conclusion of the analysis has been that the electrical response of the system was dominated by the hopping charge transport.
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