Piezoelectricity in multi-air voids electrets

Altafim, Ruy Alberto Corrêa; Basso, Heitor Cury; Neto, Luiz Biondi; Lima, L.; Aquino, Cléber

doi:10.1109/ceidp.2005.1560771

Cited by 25 publications

(15 citation statements)

References 15 publications

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“…A few years ago, light emission from the internal voids during electrical charging has been reported [4,5]. The light emission indicates internal electric discharges which can also be investigated on the recently developed polymeric layer structures with welldefined voids [6,7]. Experimental results have demonstrated that even before the onset of light emissions, the polymer structures already exhibit a significant piezoelectric coefficient that grows linearly with the applied electric field, until electrical discharges begin at certain field strength, and the piezoelectric coefficient reaches saturation [8].…”

Section: Introductionmentioning

confidence: 98%

Dielectric barrier discharges in multi-layer polymer ferroelectrets

Altafim

Basso

Qiu

et al. 2009

2009 IEEE Conference on Electrical Insulation and Dielectric Phenomena

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Cellular polymer foams with bipolar internal space charge are known as ferro-and piezoelectrets. Light emission from the internal voids of such polymer foams during electrical charging was already reported a few years ago and allows the investigation of the underlying dielectric barrier discharges. More recently, polymeric layer structures with well-defined voids were presented as an alternative to polymer-foam ferroelectrets. The simpler and more uniform voids in layered ferroelectrets are more suitable as model systems for dielectric barrier discharges across a single gap between two polymer layers and two external electrodes. In this contribution, we report and discuss first results from electrical and optical experiments and propose a theoretical explanation for the internal charging process (including eventual back discharges) in simple multi-layer ferroelectrets.

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Section: Introductionmentioning

confidence: 98%

Dielectric barrier discharges in multi-layer polymer ferroelectrets

Altafim

Basso

Qiu

et al. 2009

2009 IEEE Conference on Electrical Insulation and Dielectric Phenomena

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“…Even though the double-layer electrets initially exhibited rather high piezoelectric activities, the shellac led to a fast deterioration and to destruction of the samples. Here, we present a new and stable piezoelectret [16] technology with Teflon®-FEP electret films and thermo-formed bubbles in between [17]. …”

Section: Introductionmentioning

confidence: 99%

Piezoelectrets from thermo-formed bubble structures of fluoropolymer-electret films

Altafim

Basso

Lima

et al. 2006

IEEE Trans. Dielect. Electr. Insul.

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Cellular and porous polymers with internal bipolar space charge can exhibit large piezoelectric thickness coefficients and have therefore led to significant advances in the understanding and the application of piezoelectricity in polymer electrets. As possible alternatives to these cellular ferroelectrets, other potentially useful configurations of space-charge electrets, such as bi-layer or multi-layer stacks of at least one "soft" porous and one "hard" non-porous electret film have been suggested and investigated. Extending the concept of cellular or porous polymer electrets with microscopic voids, we propose and describe novel piezoelectret structures with regular arrays of millimeter-sized bubbles that are formed between fluoro-ethylene-propylene (Teflon®-FEP) films via a vacuum-assisted thermal process. After internal charging by means of high impulse voltages, the bubble structures exhibit rather large piezoelectric activities in their thickness direction, with phenomenological quasi-static d 33 coefficients of up to 500 pC/N (or pm/V) which quite strongly decrease with the amplitude of the applied force. The electromechanical behavior of the new piezoelectrets has been modeled in analogy to the operation of electret microphones. , he is a visiting professor at the Institute of Physics of the University of São Paulo in São Carlos, Brazil. The main research areas of Prof. Gerhard-Multhaupt are polymer electrets and ferroelectrets, in particular the mechanisms of space-charge storage and dipole polarization in dielectric polymers and polymer composites, their ferro-, pyro-and piezoelectrical properties, and their applications in sensors and actuators, as well as the nonlinear optical properties of polymers, and more recently also the physics of musical instruments. From 1974From until 1979 he was a fellow of the Studienstiftung des Deutschen Volkes. In 1988, he was awarded an ITG-Preis by the Informationstechnische Gesellschaft im VDE. In 1989, he received a Silver medal from the Stiftung Werner-von-Siemens-Ring. In 2001, he was awarded the first Technologietransfer-Preis by the Technologie-Stiftung Brandenburg and the Prof.-Adalbert-Seifriz-Preis by the Verein Technologie-Transfer Handwerk for his technological collaborations with small industrial companies. Reimund Gerhard-Multhaupt is a member of the American, European and German physical societies. Since 2002, he serves as Digest Editor of the IEEE Dielectrics and Electrical Insulation Society.

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“…Piezoelectric d 33 coefficients of cellular i-PP up to 1200 pC/N were measured [22]. Recently, several other cellular or layered polymers, such as COC [23,24], PETP [25,26] and FEP/PTFE [27][28][29] were also investigated in relation to piezoelectric activity.…”

Section: Introductionmentioning

confidence: 99%

Development of porous polypropylene blends with NA11 particles and glass hollow spheres by biaxial stretching for electret applications

Behrendt

Altstädt

Schmidt

et al. 2006

IEEE Trans. Dielect. Electr. Insul.

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In the present work, the development of cellular films by stretching isotactic polypropylene (i-PP) filled with NA11 (2,2'-methylene-bis-(4,6-di-tert-butylphenyl)-phosphate) particles and hollow glass spheres is reported. Morphology, electret properties and piezoelectric activity are investigated. An enhancement of the charge storage stability for the cellular films is due to the formation of cavities, which retard the drift of charges through the volume of the film. Furthermore, the cellular stretched i-PP films with hollow glass spheres were made piezoelectric by suitable corona poling method. Films were stretched to draw ratios of 3.5 : 3.5 (medium stretched) and selected samples were drawn to ratios of 5:5 (highly stretched). The applied draw ratio was found to directly influence the cavity formations and by this the electret and piezoelectric properties. Excellent electret properties were obtained in the case of highly stretched i-PP films containing 10 wt% of NA11, known as a nucleating agent additive for i-PP. Additionally, piezoelectric activity (d 33 = 179 pC/N) was observed in these films. i-PP films with glass spheres showed piezoelectric coefficients between 17 and 170 pC/N, depending on glass sphere size and concentration as well as on draw ratio.

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Piezoelectricity in multi-air voids electrets

Cited by 25 publications

References 15 publications

Dielectric barrier discharges in multi-layer polymer ferroelectrets

Dielectric barrier discharges in multi-layer polymer ferroelectrets

Piezoelectrets from thermo-formed bubble structures of fluoropolymer-electret films

Development of porous polypropylene blends with NA11 particles and glass hollow spheres by biaxial stretching for electret applications

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