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Electric modulus and polarization studies on piezoelectric polyimides
Author(s) -
Gonzalo Beatriz,
Vilas Jose Luis,
San Sebastián María,
Breczewski Tomasz,
PérezJubindo Miguel Ángel,
de la Fuente María Rosario,
Rodríguez Matilde,
León Luis Manuel
Publication year - 2011
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.34702
Subject(s) - piezoelectricity , materials science , dielectric , glass transition , dipole , amorphous solid , thermal stability , electric field , polymer , polarization (electrochemistry) , composite material , dynamic mechanical analysis , electret , polarization density , optoelectronics , organic chemistry , chemistry , physics , magnetization , quantum mechanics , magnetic field
The piezoelectric polymeric sensors and actuators are widely valued because of their low density, availability to obtain complex shapes, and easy processing among other characteristics. However, there are not many useful piezoelectric polymers. Aromatic polyimides are high‐performance polymeric materials characterized by thermal stability, chemical resistance, and excellent mechanical properties. Besides, some of these polymers have been reported as candidates to present piezoelectric properties. Our research focuses in the electric characterization of three piezoelectric amorphous aromatic polyimides, containing CN groups in different number and positions. The piezoelectricity in amorphous polymers is mainly due to the orientation polarization of the molecular dipoles, which is induced by the application of an external electrical field to a temperature over their glass transition temperature ( T g ). Polyimides are measured by thermally stimulated depolarization currents and dielectric spectroscopy and the analysis of the dielectric data has been performed using the electric modulus formalism to separate conductive and dipolar processes. These measurements have evidenced that the frozen‐in polarization is mainly due to the dipole orientation of the dipolar CN groups, allowing us to understand in depth the mechanism of polarization that contributes to the piezoelectric properties. This will facilitate the obtention of materials with the best possible piezoelectric properties, comparable to those currently available but with higher mechanical and thermal performance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012