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Thin porous flexible films with large piezoelectric effects are now known as ferroelectrets or piezoelectrets. Recent developed techniques for fusing fluoropolymer films with well-controlled cavities have promoted a new class of this material, thermally more stable. In this work, we investigate the underwater behavior of a multi-layer piezoelectret with open tubular channels. For this propose an electrically...
Piezoelectrets from thin electrically charged cellular polypropylene-foam films have been suggested for numerous transducer applications, such as force sensors for keyboards, flat microphones for conference environments, or devices for ultrasound generation and detection. In addition to polypropylene piezoelectrets, other materials systems — such as thermo-fused polymer-film stacks — were developed...
Multi-layer piezoelectrets of fluoropolymers prepared by thermal fusing processes have been already reported in different techniques. In this work, we present new piezoelectrets prepared without any heating procedure. The method used to produce these structures consists of bonding at least two films of fluoroethylenepropylene (FEP) with an adhesive tape between then. The cavities, necessary for the...
Stacked ferroelectret film systems have been proposed as a simple solution to increase the piezoelectricity beyond that of a single ferroelectret layer. Recent developments in ferroelectret research have also shown that organized void structures can be produced by thermal lamination of polymer films. Here, the two approaches are combined to produce multi-layer ferroelectrets with controlled voids...
Significant efforts are devoted to developing new ferroelectrets with well-controlled void distributions or uniform voids and with good long-term and thermal stability of the piezoelectricity. Here, we describe the concept, the fabrication, and the most relevant properties of fluoropolymer ferroelectret systems with three separate films of fluoroethylenepropylene (FEP), alternating with two polytetrafluoroethylene...
Recently, a new type of polymeric piezoelectret has been proposed and demonstrated with two fluoroethylenepropy-lene (FEP) films that are laminated around a polytetrafluoroethy-lene (PTFE) template at 300°C. After removing the PTFE template, a two-layer FEP film with open tubular channels is obtained. After internal bipolar charging, the channels form large and easily deformable electric dipoles that...
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