Cellular Polymer Ferroelectret: A Review on Their Development and Their Piezoelectric Properties

Abstract

Because of their ability to show ferroelectret behavior when exposed to an external electric field, cellular polymers have been recently considered for ferroelectret applications. These cellular polymer films can be produced by stretching or foaming, but depending on the application and conditions, different polymers, such as polypropylene (PP), poly(ethylene terephthalate), poly(ethylene naphthalate), poly(tetrafluoro ethylene), cross-linked PP, and some cyclo-olefines, have been considered. Nevertheless, cellular PP was the most investigated material because of its outstanding properties such as high piezoelectric d 33 coefficient, flexibility, good fatigue resistance, good charge trapping properties, and low cost. In this review, recent advances related to the materials used for ferroelectret applications and their processing are discussed. The effect of different parameters such as pressure, electrical breakdown strength of the gas phase, presence of fillers, and service temperature on the d 33 coefficient is presented and discussed. C

New piezoelectric composites based on isotactic polypropylene filled with silicate

“…These holes of different shapes and sizes are sometimes filled with modifier particles. Such voids are usually responsible for the accumulation of piezoelectric charge in the polymeric materials [5][6][7][8][9]11]. In most cases, a lack of wettability and adhesion is observed, which is caused by immiscibility of components.…”

“…In such cavities, the electric charge is entrapped, which results in formation of permanent electric dipoles [5][6][7][8][9].…”

Characterization of piezoelectric films of foamed polyethylene obtained by extrusion

“…flexibility, durability, low density) and the possibility of forming any shapes and sizes of products in conventional molding processes. It has been repeatedly confirmed that good piezoelectric properties have semicrystalline polymers with a cellular structure [14,[17][18][19][20]. On the basis of reviewing the current literature shows that an isotactic polypropylene is already recognized as a potential piezoelectric material (besides of PVDF or PFTE) [12][13][14][15][16], however, other polyolefins, including polyethylene, are still not well investigated.…”

Polymer ferroelectret based on polypropylene foam: piezoelectric properties prediction using dynamic mechanical analysis

“…To ensure a maximum N 2 saturation, a stream of SC‐N 2 with a pressure of 7 MPa and a flow rate of 5 ml/min was injected in zone 2 of the extruder, which was controlled by a mass flow meter/controller model F‐201CV‐5 K0‐ABD‐22‐V (Hoskin Scientific Co., USA). More information on the experimental setup can be found in our previous work …”

“…To achieve a good eye‐like cellular morphology, which is suitable for good piezoelectric properties, the samples were uniaxially stretched in the melt state between the die exit and the first roller of the calendar (distance of 10 cm). After some processing and composition optimization in terms of screw configuration, temperature profile, die temperature, stretching speed, and nucleating agent, different closed‐cell foamed PP films, with and without nucleating agent, were produced. The specifications of the selected samples studied here are reported in Table .…”