Dielectric properties of segmented polyurethanes for electromechanical applications

Abstract

Please cite this article as: Jomaa MH, Seveyrat L, Lebrun L, Masenelli-Varlot K, Cavaille JY, Dielectric properties of segmented polyurethanes for electromechanical applications, Polymer (2015), AbstractThe paper deals with electromechanical and dielectric properties of polyurethanes (PU) blockcopolymers. Most of the works published in the literature only consider electrostriction at room temperature at a given frequency. In this work, it is shown that electrostrictive coefficient M E is divided by 3 to 10 at increasing frequency over 3 decades of frequency, depending on the ratio of hard to soft segments in PU. Thus it is important to analyze the energy conversion efficiency by investigating the dielectric and viscoelastic properties. This work is divided into two parts. The first oneThis work deals with the study of dielectric properties of 3 PU with different fractions of hard segments. Three relaxation phenomena (β, α and conduction) were investigated for each PU in the temperature-frequency range studied here, in order to optimize the copolymer composition in view of their best efficiency as actuators or mechanical energy harvesting devices. Part 2 will analyze the effect of viscoelastic properties on electrostriction efficiency.

Optimization of mechanical and dielectric properties of poly(urethane–urea)-based dielectric elastomers via the control of microstructure

“…In addition, even though many literature investigated the dielectric properties of PU/PUUs, [19][20][21][22][23][24] the effects of microstructure of PUUEs on dielectric and mechanical properties still have less been understand, so far. For example, how the hydrogen bonding structure and crystallinity of hard domains and microphase separated network structures contribute to the dielectric constant, dielectric loss and breakdown strength of PUUs?…”

Influence of the crystallization on the molecular mobility and ionic DC conductivity behaviors of relaxor ferroelectric P(VDF‐TrFE‐CTFE) terpolymers

“…Table . A considerable increase in of 35.46 3 kJ mol −1 was obtained for the fully crystallized terpolymer as observed in several glass formers, suggesting the existence of a small energy barrier between the pristine terpolymer and its crystallized counterparts. Such results also imply that a local motion below changes the relaxation dynamics, giving rise to the thermodynamic stability as the crystallization evolves.…”

Dielectric relaxations of Acrylic-Polyurethane hybrid materials

“…It is well known that PU segments have a strong tendency to crystallize [22]. The investigated samples show no signature of crystallization, but this circumstance can favour the development of some orientational correlation [23].…”