Thermally stable cellular poly(vinylidene) ferroelectrets: Optimization of CO₂ driven inflation process

Abstract

Electrically charged cellular ferroelectrets can show excellent thermally stable piezoelectric activity and are therefore progressively used in electrochemical transducers. Given that an optimized cellular structure is a key for improving charge density and the associated piezoelectric properties in this material, we investigated the influence of CO2 inflation treatment using various gas diffusion expansion or inflation procedures on the piezoelectric d33 coefficient and thermal stability of cellular poly(vinylidene) ferroelectrets and compare with the results (partially) obtained by N2 inflation as reported in our previous study (Jahan, Mighri, Rodrigue, Ajji, J. Appl. Polym. Sci. 2019, 136, 47540). Samples were prepared using the conventional extrusion–stretching–inflation–corona charging method. Maximum d33 coefficient for CO2‐inflated samples is found to be around 30% higher than that of N2‐inflated samples (327 pC/N compared to 251 pC/N) by stepwise pressure application method. The key parameters addressed in the inflation procedures are the changes in sample thickness, morphology, and the void‐height distribution in both gas treatments. The ferroelectrets show excellent thermal stability for up to 4 days at 90, 110, and 120 °C in both treatments with a slightly improved performance in CO2 gas. The higher activation energy of CO2‐inflated samples (0.52 eV) than the N2‐inflated ones (0.43 eV) further confirms the stability data. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47929.

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“…Also, they showed that the highest d 33 (from 137 to 251 pC N À1 ) was generated when there was increase in the inflation pressure (from 3 to 5 MPa) at 130 °C constant temperature for a certain time. [107] More recently, Xu et al [108] fabricated a foamed PVDF/ multiwalled carbon nanotube (MWCNT) piezonanocomposite. The foam layer was created by the bead foaming technology utilizing supercritical carbon dioxide (scCO 2 ).…”

“…Recently, Jahan et al [ 107 ] produced cellular PVDF–montmorillonite (MMT)–CaCO 3 ‐based piezoelectret films involving uniaxially stretched, GDE treated, and corona charged. Recently, Jahan et al [ 107 ] produced cellular PVDF‐montmorillonite (MMT) ‐CaCO 3 ‐based piezoelectret films involving uniaxial stretching, GDE treatment, and corona charging.…”

“…Recently, Jahan et al [ 107 ] produced cellular PVDF–montmorillonite (MMT)–CaCO 3 ‐based piezoelectret films involving uniaxially stretched, GDE treated, and corona charged. Recently, Jahan et al [ 107 ] produced cellular PVDF‐montmorillonite (MMT) ‐CaCO 3 ‐based piezoelectret films involving uniaxial stretching, GDE treatment, and corona charging. Also, they showed that the highest d 33 (from 137 to 251 pC N −1 ) was generated when there was increase in the inflation pressure (from 3 to 5 MPa) at 130 °C constant temperature for a certain time.…”

“…Also, they showed that the highest d 33 (from 137 to 251 pC N −1 ) was generated when there was increase in the inflation pressure (from 3 to 5 MPa) at 130 °C constant temperature for a certain time. [ 107 ]…”