Electroactive polymers are widely studied because of their large electrical-field-induced strain. Their flexibility and their ability to be deposited on large surfaces make them promising candidates as electroactive materials for actuators or energy-harvesting devices. For actuation purposes, the material efficiency is directly related to the electrical-field-related electrostrictive coefficient M 33 through S 33=M 33E 2, where S 33 is the electrical-field-induced strain and E is the applied electrical field. Numerous studies concern the increase of M 33, but very few have been devoted to its saturations versus electrical field. To this end, the present paper describes the variation of M 33 versus thickness, composition, frequency, and electrical field for polyurethane-based composites. Based on the saturation of the electrical-field-induced polarization within the studied polymer composites, a model of the M 33 behavior was also proposed, and it was found to show a good agreement with the experimental data. In addition, this model predicts the dielectric constant and the saturation electrical field to be the key parameters ruling the M 33 saturation.
- Electrostrictive coefficient
- Polyurethane composites