Abstract
Piezoelectric polymers characterized by flexibility are sought for applications in microelectronics, medicine, telecommunications, and everyday devices. The objective of this work was to obtain piezoelectric polymeric composites with a cellular structure and to evaluate their usefulness in practice. Composites based on polyolefins (isotactic-polypropylene and polyethylene) with the addition of aluminosilicate fillers were manufactured by extrusion, and then polarized in a constant electric field at 100 V/µm. The content of mineral fillers up to 10 wt% in the polymer matrix enhances its electric stability and mechanical strength. The value of the piezoelectric coefficient d33 attained ~150 pC/N in the range of lower stresses and ~80 pC/N in the range of higher stresses, i.e., at ~120 kPa. The materials exhibited high durability in time, therefore, they can be used as transducers of mechanical energy of the human motion into electric energy. It was demonstrated that one shoe insert generates an energy of 1.1 mJ after a person walks for 300 s. The miniaturized integrated circuits based on polyolefin composites may be applied for the power supply of portable electronics. Due to their high sensitivity, they can be recommended for measuring the blood pulse.
Highlights
One of the challenges of contemporary technology is obtaining piezoelectric materials based on readily available polymers for the production of biomedical, portable sensors
The purpose of this work is to present useful piezoelectric properties of composites made of different types of polyolefins: Isotactic polypropylene (i-PP), high density polyethylene (HDPE), and medium density polyethylene (MDPE), as well as two aluminosilicate mineral fillers (Sillikolloid or glass beads)
The film of piezoelectric composites was obtained by extrusion in a two-step process in carefully selected conditions, which ensured good distribution of the filler in the polymer matrix and the reproducibility of the demanded properties
Summary
One of the challenges of contemporary technology is obtaining piezoelectric materials based on readily available polymers for the production of biomedical, portable sensors. The most known and applied material of this kind is poly(vinylidene fluoride), PVDF, as well as its copolymers [3,4,5] This crystalline polymer has fluorine atoms with the highest electronegativity, and highly polarized C–F bonds in each repeating unit: –(CF2 –CF2 )n –. PVDF occurs in several polymorphic forms with different properties, in which the β phase shows the highest dipole moment. Nowadays, this is used in highly professional applications [5,6,7,8,9,10,11,12,13]
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