Abstract
This paper investigates energy harvesting performances of porous piezoelectric polymer films to collect electrical energy from vibrations and power various sensors. The influence of void content on the elastic matrix, dielectric, electrical, and mechanical properties of porous piezoelectric polymer films produced from available commercial poly(ethylene-co-vinyl acetate) using an industrially applicable melt-state extrusion method (EVA) were examined and discussed. Electrical and mechanical characterization showed an increase in the harvested current and a decrease in Young’s modulus with the increasing ratio of voids. Thermal analysis revealed a decrease in piezoelectric constant of the porous materials. The authors present a mathematical model that is able to predict harvested current as a function of matrix characteristics, mechanical excitation and porosity percentage. The output current is directly proportional to the porosity percentage. The harvested power significantly increases with increasing strain or porosity, achieving a power value up to 0.23, 1.55, and 3.87 mW/m3 for three EVA compositions: EVA 0%, EVA 37% and EVA 65%, respectively. In conclusion, porous piezoelectric EVA films has great potential from an energy density viewpoint and could represent interesting candidates for energy harvesting applications. Our work contributes to the development of smart materials, with potential uses as innovative harvester systems of energy generated by different vibration sources such as roads, machines and oceans.
Highlights
Piezoelectric polymers have been considered for energy harvesting applications [5–8]
The material has remarkable fatigue resistance and environmental stability [9], but it has not been recognized as a promising energy harvesting material because of its low piezoelectric constants when compared to PZT ceramics [10–12]
Zhang et al [15] showed energy harvesting applications with this type of cellular material based on piezoelectret fluorocarbon polymers with a power collected value up to 109 W [16]
Summary
Piezoelectric materials are optimized for special applications ranging from mechanical structures to electronic devices, from applications in structural health monitoring and aerospace to active vibration damping and the automotive industry [1–4]. Piezoelectric polymers have been considered for energy harvesting applications [5–8]. Researchers investigated porous piezoelectric polymers consisting of an ionized cellular polypropylene film made by a chemical elaboration method using nitrogen gas [13]. Excellent piezoelectric coefficients up to 2000 pC/N for specific morphologies and mechanical conditions comparably higher than those of piezoceramics were identified [14,15]. In order to demonstrate the ability of the porous piezoelectric polymers in a harsh environment, Zhong et al [16] fabricated PET/EVA/PET laminated films and ionized them by a corona charging method. Zhang et al [15] showed energy harvesting applications with this type of cellular material based on piezoelectret fluorocarbon polymers with a power collected value up to 109 W [16]. Kachroudi et al [17] examined air-spaced cantilevers elaborated from a PDMS porous piezoelectric material for energy harvesting applications. For frequencies ranging from 5 Hz to 200 Hz, the output power reached a maximum of 136 nW and remained stable at 103 nW
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