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Polymers and Their Composites for Wearable Electronics
Published in Inamuddin, Mohd Imran Ahamed, Rajender Boddula, Tariq Altalhi, Polymers in Energy Conversion and Storage, 2022
Svetlana Jovanović, Dragana Jovanović
Poly(vinylidene fluoride) (PVDF) is a piezoelectric polymer, suitable for WE energy application thanks to its high flexibility, sensitivity, ductility, low price, and biocompatibility (Guo et al. 2020). To create PVDF fibers, the most often used technique is electrospinning (Forouharshad et al. 2019). The electroactivity of a PVDF fiber is highly dependent on the fiber thickness due to changes in the ratio between the α- and β-phase (Forouharshad et al. 2019). The percentage of the β-phase can vary from 45 to 90% (Guo et al. 2020). By adding additives such as inorganic salt (like LiCl), the formation of the β-phase can be improved and lead to an enhancement in voltage output of 5 V at 100 Hz (Forouharshad et al. 2019). Using this approach, efficient energy harvesting textiles can be produced.
P
Published in Joseph C. Salamone, Polymeric Materials Encyclopedia, 2020
Poly(vinylidene fluoride)PVDF, commonly abbreviated as PVDF or PVF2, is a polymer with increasing scientific attention and industrial importance because of its outstanding electrical properties, its chemical and weather resistance, its durability, and its biocompatibility. For a number of applications, particularly for electronic purposes, random copolymers with small amounts of trifluoroethylene or monofluoroethylene are advantageous since they crystallize immediately in a polar crystal modification. PVDF exhibits a number of high-performance properties. It is a tough, hard, aging, heat resistant, and thermally stable engineering resin. It is, consequently, highly weather resistant, particularly against extreme temperature changes, and it is resistant against most chemicals. The strong electric moment of the chain repeat unit, at the one hand, and the easy crystallizability of the PVDF, at the other hand, are responsible for a number of outstanding electric properties of this polymer.
Polymer Microsystems: Materials and Fabrication
Published in Mohamed Gad-el-Hak, MEMS, 2005
Gary M. Atkinson, Zoubeida Ounaies
Polyvinylidene fluoride (PVDF) is a fluorocarbon whose main use was initially as an inert lining or pipework material in chemical plants, where its combination of processability, mechanical strength, and excellent chemical resistance are advantageous [Gallantree, 1983]. PVDF can be shaped into simple or complex configurations via extrusion, solution casting, and molding to form films, sheets, and tubes. This great flexibility in design, coupled with its pliability and relative low cost, offer an attractive basis for MEMS as a substrate as well as a functional material. Interest in the electrical properties of PVDF began in 1969, when Kawai showed that thin films that had been poled exhibited a very large piezoelectric coefficient, 6–7 pCN−1, a value about ten times larger than had been observed in any other polymer. As a result of Kawai’s discovery, PVDF became better known for its piezoelectric properties and has been extensively investigated as a sensor and actuator since that time. Today, PVDF accounts for virtually all of the commercially significant piezoelectric polymer applications.
Microstructure design and optimization of multilayered piezoelectric composites with wavy architectures
Published in Mechanics of Advanced Materials and Structures, 2023
Xiaoyu Zhao, Jinhui Wang, Qiang Chen, Haobin Jiang, Caifeng Chen, Wenqiong Tu
Piezoelectric materials are important components for sensors and actuators because of their characteristics for converting energy between the mechanical and electrical sources. Among piezoelectric materials, the piezoelectric ceramics PZT (lead zirconate titanate) has excellent piezoelectric performance, and its piezoelectric constant (d33) is between 220 and 600 pCN−1 [1–4]. However, it has certain drawbacks like the brittleness, non-conformability and containing lead-based materials that have adverse effects on environment [5]. PVDF (polyvinylidene difluoride) has an excellent flexibility due to its commensurate copolymer structure, an excellent electro-active property [6–9] with a piezoelectric constant (d33) between 20 and 40 pCN−1. The combination of piezoelectric ceramics PZT with polymers PVDF could produce piezoelectric polymer composites that are well suitable for structural and functional components of microelectromechanical systems (MEMS). Currently, the applications of PZT/PVDF piezoelectric composites are emerging in flexible electronics due to their excellent mechanical properties, good environmental adaptability, and outstanding energy harvesting performance, especially in the flexible piezoelectric nanogenerators [10–15].
Direct fabrication of electrospun branched nanofibers with tiny diameters for oil absorption
Published in Journal of Dispersion Science and Technology, 2021
Bilal Zaarour, Lei Zhu, Xiangyu Jin
As one of the most commonly used polymer for generating electrospun nanofibers, polyvinylidene fluoride (PVDF) holds noteworthy advantages such as piezo-, pyro- and ferroelectricity, high sensitivity, chemical resistance, high mechanical strength, flexibility, thermal stability, and its ability to be formed in various structures.[27–34] Therefore, it has been used in different applications including oil-water separation,[17] energy harvesting,[25] air filtration,[35] a separator for lithium-ion battery,[36] self-cleaning surfaces,[32] support for preparing composite membranes,[37] membrane distillation,[38] and so on.
Enhancement investigations on dielectric and electrical properties of niobium pentoxide (Nb2O5) reinforced poly(vinylidene fluoride) (PVDF)- graphene oxide (GO) nanocomposite films
Published in Journal of Asian Ceramic Societies, 2021
Srikanta Moharana, Ram Naresh Mahaling
Niobium pentoxide (Nb2O5), one of the most important transition metal oxides has immense interest due to their potential applications in gas sensors, catalysts, micro-electronics, and optoelectronic industries [11]. However, the Nb2O5 is an n-type semiconductor with a band gap of about 3.4 eV, low in comparison with other oxide [12]. This niobium pentoxide has several advantageous characteristics including surface area enables for easy modification by intercalation, superficial modification and formation of nanosheets or nanoscrolls [13–15]. Moreover, it is also used as promising doping agent for tailoring nanostructured composites materials for potential applicability in the various fields. Niobium pentoxide is biocompatible as well as it enhances bioactivity and corrosion resistance of the respective nanocomposites [16–18]. In this study, the niobium pentoxide-reinforced graphene-oxide-based polymer nanocomposites have achieved significant increase in dielectric constant with improved conductivity and suppressed loss. Besides, polymers are most normally used as dielectric materials with high mechanical flexibility, good process ability, low cost, and high dielectric strength [19]. Especially, the ferroelectric polymers such as poly(vinylidene fluoride) (PVDF) and its co-polymers poly(vinylidene fluoride co-hexa fluoropropylene) (PVDF-HFP), which is a semi-crystalline thermoplastic polymeric materials with extraordinary high piezo and pyro electric coefficient, better thermal stability, chemical resistance, high dielectric constant (≈10) and high break down strength [20–22].