Evaluation of prototype piezoelectret made of foamed butyl rubber and fluorinated ethylene propylene film

Background Sensors use functional materials such as piezoelectrics. Research on functional materials is thus important. Objective In the present study, we fabricated a piezoelectret made of foamed butyl rubber and FEP films, and examined its power generation characteristics. A piezoelectret made of butyl rubber was also fabricated for comparison. Methods The surface potential was measured as a characteristic parameter. To measure the voltage generated in the test specimen, an experiment was conducted in which an impulsive and cyclic compressive load was applied to the test specimen using a shaker. The piezoelectric stress constant d 33 for the test specimens was calculated assuming that the power generation characteristics of the test specimens is the same as those of the piezoelectric material. Results The surface potential after 2 weeks for the piezoelectrets made of foamed butyl rubber was −0.493 kV and that for the piezoelectrets made of butyl rubber was lower at −0.166 kV. The d 33 after 2 weeks was estimated to be 698.6 pC/N for the piezoelectret made of foamed butyl rubber and 103 pC/N for the piezoelectret made of butyl rubber. Conclusions A piezoelectret made of foamed butyl rubber was fabricated and evaluated. It is suggested that the voids inside the butyl rubber have a positive effect on the power generation performance.