Flexoelectricity in Fluoropolymer/Al Reactives

Author: Mikel Zaitzeff, Department of Chemical and Biological Engineering

Mentor: Dr. Lori Groven, Department of Chemical and Biological Engineering

In the past few years, there has been increased interest in the development of smart reactives. Fluoropolymers are used as an oxidizer in composite reactive systems and can exhibit piezoelectricity. The composite reactive systems THV/Al and PVDF/Al have been explored for their ability to be switched to a more sensitive state. Early work indicates that even non-piezoelectric composites could exhibit sensitization behavior, but the mechanism was not detailed. A possible explanation is flexoelectricity. Flexoelectricity is present in all dielectric materials and generates an electric polarization under a strain gradient or stress and therefore the requirement that the material be non-centrosymmetric is bypassed. This allows for flexoelectric materials to produce similar effects as the piezoelectric effect. In this work, THV and PVDF loaded with micron scale aluminum between 0 and 50 weight percent were measured for their flexoelectric coefficients. The phase identification for PVDF and THV was identified using fourier-transform infrared spectroscopy and X-Ray diffraction. There was a linear increase in flexoelectric coefficient between 5.03 * 10^-9 C/m and 7.83 * 10^-9 C/m for both composite reactive systems. PVDF exhibited the electroactive β and γ phases and THV exhibited a spontaneous polarization peak. THV is not a true piezoelectric material and exhibited larger flexoelectric coefficients indicating that a true piezoelectric material is not needed for a significant flexoelectric effect and sensitization behavior.