Caracterização de polímeros ferroelétricos: metodologia e resultados / Characterization of ferroeletric polymers: methodology and results

AUTOR(ES)

Célio Wisniewski

DATA DE PUBLICAÇÃO

1999

RESUMO

In this work three experimental setups were developed, the constant current method (CC) (derived from the corona mode with constant current), the ramp voltage method (RT) (derived from the bipolar hysteresis measurements) and measurement of the pyroeletric coefficient employing a sinusoidal temperature variation. These methods were used to study the ferroelectric polarization in polymers such as PVDF, PVF, copolymer of P(VDF-TrFE) and P(VDF-TrFE) - PMMA blend. From x-ray, electric polarization and pyroelectric measurements it was found that part of the total polarization decays after removing the electric field. The dependence of such decaying polarization on the rate of increasing of the electric field, on the maximum field applied to the sample and the time interval of short-circuit between successive measurements was investigated. The value of the remanent polarization and the coercive field was determined for polymeric materials listed above and a comparison of the results obtained using the CC and RT method was performed.

ASSUNTO(S)

hysterises polarization dieletrics polímeros polarização dielétricos polymers histerise ferroeletrecity ferroeletrecidade

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