Effect of the inflation strategy on the piezoelectric response of cellular poly(vinylidene fluoride) ferroelectret

Cellular poly(vinylidene fluoride) (PVDF)‐montmorillonite (MMT)‐calcium carbonate (CaCO 3 ) based piezoelectret films were produced using uniaxial stretching and various gas diffusion expansion (GDE) treatments followed by corona charging. The cross section micrographs revealed that a cellular structure was developed at the interface between the solid CaCO 3 particles and the polymer matrix. Sample characterization showed that the piezoelectric coefficient (d 33 ) was a function of the external gas pressure and treatment temperature, as well as the way they were applied. The results also showed that the maximum d 33 was obtained when the inflation pressure was increased stepwise from 3 to 5 MPa at a constant treatment temperature of 130°C for a certain period of time. Finally, the overall electromechanical performance of the cellular PVDF piezoelectrets is discussed in terms of the GDE procedure and the developed microstructures. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47540.