Use of high frequency dielectric spectroscopy to investigate ferroelectric and melting transitions in copolymers of vinylidene fluoride

The dielectric strength Delta epsilon and the relaxation time tau in copolymers of vinylidene fluoride (VDF) are evaluated in terms of a dipolar two-site model in the ferro, para, and melt regimes. It is shown that the two-site model can be applied to the experimental data to give a good qualitative understanding of the relaxation behavior of the copolymers of VDF. As an example, Delta epsilon and tau of BDF/TrFE (trifluoroethylene) (65/35) are shown as a function of temperature on heating and subsequent cooling at 0.5 degrees C/min. The temperature-dependent remnant polarization which fits the ferro-para transition on heating is also shown.<>