Improvement of electrostrictive properties of a polyether-based polyurethane elastomer filled with conductive carbon black

Abstract

International audienceThe electrostrictive properties of a polyether-based polyurethane elastomer and its corresponding composites filled with conductive carbon black (CB) were studied by measuring the thickness strain SZ induced by external electric fields E. For films with thicknesses of approximately 50 μm, the apparent electrostrictive coefficient M was measured at low electric fields, E ⩽ 4 V/μm, and different CB contents (up to a volume fraction of 2%). Dielectric measurements in AC mode were performed in order to determine the percolation threshold fc, which was 1.25 v%. This optimal volume fraction yielded a remarkable threefold increase in M, associated with an increase of the dielectric constant by a factor 7, in comparison with pure PU. This enhancement of the electric field-induced strain and apparent electrostriction was mainly triggered by an increase of the dielectric constant, even if the intrinsic electrostriction coefficient Q was decreased. The nanocomposites thus seem to be very attractive for low-frequency electromechanical applications. Above fc, their conductivity was raised and their electrostrictive activity lost. Finally, there is a good agreement between the experimentally determined dependence on the CB content of the M coefficient and the theoretical estimation calculated from dielectric and mechanical measurements

Simultaneously improved actuated performance and mechanical strength of silicone elastomer by reduced graphene oxide encapsulated silicon dioxide

“…A commercial grade of siloxane (PDMS) (DC3481 184) and the curing agent (81-F) were purchased from Dow Corning Co., Ltd. (America). The viscosity and density of PDMS material used are 22.1 Pa s and 1.213 g/cm 3 , respectively. Potassium permanganate (KMnO 4 , 99.5%), sulfuric acid (H 2 SO 4 , 98%), sodium nitrate (NaNO 3 , 99.0%), hydrogen peroxide (H 2 O 2 , 30%), hydrochloric acid (HCl, 37%), and methanol (CH 3 OH, 99.5%), which were all used for the preparation of graphite oxide, were supplied by Beijing Chemical Reagents Co., Ltd. (China).…”

“…Thus, they have received much attention in the past two decades [1,2]. A dielectric elastomer actuator (DEA) can shrink in the thickness direction and expand in the plane direction by applying an electric field across the film thickness [3]. By virtue of the excellent properties such as large strain, fast response, lightweight, reliability, high energy density, and high electromechanical coupling efficiency, DEAs find applications in artificial muscles, sensors, micro air vehicles, flat-panel speakers, micro-robotics, and responsive prosthetics [4][5][6][7][8].…”

Electrostrictive polymers for mechanical energy harvesting

“…38,39 Losses then decrease with the frequency except for the frequencies where polarization mechanisms disappear. 33 Maximum Energy Harvesting For every energy-harvesting technique presented in the ''Energy-Harvesting Techniques'' section, it can be seen that the electrostrictive coefficient M appears to be an important parameter to increase the scavenging abilities of the system. Although the ''Increase of the Dielectric Constant and of the Electrostrictive Coefficient with the Help of Fillers'' section provides a description of the various methods available to increase this coefficient, the goal of this part is to present a figure of merits able to realize a comparison of the different technique available for harvesting energy.…”

Electrostrictive Polymers for Vibration Energy Harvesting

“…Several studies have analyzed and enhanced the energy conversion performance of electrostrictive polymers, both in terms of actuation and energy harvesting ( [12,19,20]). An ideal approach in order to obtain polymers with specific improved dielectric properties is represented by a challenging synthesis of new molecular architectures.…”