Fabrication of Dielectric Elastomer Composites by Locking a Pre-Stretched Fibrous TPU Network in EVA.

Liang Jiang,Jianwei Ma,Yanfen Zhou,Zhiqing Jiang,Shaojuan Chen,Yuhao Wang,Fang Zhou

doi:10.3390/ma11091687

Abstract

Dielectric elastomer (DE) composites with high electrical breakdown strength and large voltage-induced deformation were developed by retaining pre-stretched thermoplastic polyurethane (TPU) fibers in ethylene vinyl acetate copolymer (EVA). The microstructure of the candidate E-TPU fiber membrane and EVA coated E-TPU (E-TPU/EVA) film were characterized by scanning electron microscopy (SEM). The quasi-static and dynamic mechanical property, and the electromechanical properties, including the dielectric constant, dielectric loss tangent, and electromechanical sensitivity, of the DE composites were evaluated. Initially, tensile tests demonstrated that the DE composites based on E-TPU/EVAs had a higher elongation at break of above 1000% but a low elastic modulus of approximately 1.7 MPa. Furthermore, dielectric spectroscopy showed that the E-TPU/EVA had a dielectric constant of 4.5 at the frequency of 1000 Hz, which was 1.2 times higher than that of pure EVA film. Finally, it was found from electromechanical test that the voltage induced strain of E-TPU/EVA rose to 6%, nearly 3 times higher than that of pure TPU film, indicating an excellent electromechanical property. The DE composites developed have demonstrated the potential to be good candidate materials in the fields of artificial intelligence, biomimicry and renewable energy.

Highlights

Dielectric elastomers (DEs) are considered smart materials capable of responding to electrical stimuli by changing their shapes [1,2]
A novel DE material was fabricated by combining a soft electrospun thermoplastic polyurethane (TPU) membrane with ethylene vinyl acetate (EVA)
The pre-stretched TPU fibers embedded in EVA presented a muscle-like structure and possessed excellent electromechanical properties

Summary

Introduction

Dielectric elastomers (DEs) are considered smart materials capable of responding to electrical stimuli by changing their shapes [1,2]. DEs are sometimes referred to as “artificial muscle” materials because they can readily resemble natural muscle under strain, as well as display similar actuation pressures, response speeds, electromechanical energy densities and coupling efficiencies. They have been proposed for multiple applications in the fields of biomimicry, artificial intelligence, sensors and energy harvesting [7,8,9,10,11]. Where ε′ is the relative permittivity or the dielectric constant of the DE material, ε0 is the permittivity of the free space

Methods

Results

Conclusion