Preparation And Study Of Dielectric Elastomer With High Electrostrictive Properties

Dielectric elastomer (DE) is a class of smart material which can convert electrical energy into mechanical energy. Due to high conversion efficiency, high energy density, large deformation, low viscoelastic hysteresis, and fast response speed, dielectric elastomer shows great potential in fields of micro actuators, artificial muscles, and robots. Currently, researchers focus on developing new materials with high dielectric constant and low modulus, which is beneficial to generate large deformation at low voltage, since materials available at present have disadvantage more or less. In this paper fluorosilicone (FVMQ) rubber-based and gelatin-based dielectric elastomer were prepared, and their thermal properties, electrical properties, and electromechanical performance were studied. The main works are as follows:FVMQ rubber was prepared through post curing process and different content of crosslinking agent was used in order to select the optimal value. This material showed good heat resistance, high dielectric constant (-6.5), low dielectric loss tangent (<0.02), and relatively low elastic modulus (-0.5MPa). As a result, it exhibited very high electromechanical sensitivity P up to 12.37MPa-1, which leaded to the elastomer generate large actuated strain at relative low electrical filed strength. It can generate actuated strain of 15% at the electric field of 32 kV·mm-1.Adding the optimal amount of curing agent, FVMQ with different content of titanium dioxide (TiO2) modified by silane coupling agent KH570 was fabricated. As the increasing content of TiO2, the crosslink density, elastic modulus, dielectric constant, dielectric loss tangent and breakdown strength of TiO2/FVMQ composite increased. When the TiO2 concentration exceeded a certain value, an obvious filler network was observed, which brought dramatic increase of elastic modulus and decrease of the elongation at break. All the TiO2/FVMQ composites showed improved electromechanical performance that the maximum actuated strain increased about 153% to 38%. This composite also exhibited good electromechanical stability.FVMQ with high elongation at break was selected to study the effect of pre-strain on FVMQ-based dielectric elastomer. The breakdown strength and actuated strain of pure FVMQ and TiO2/FVMQ composite significantly increased after pre-strain. The maximum actuated strain of the pure FVMQ increase about 132% than that of without pre-strain, and the TiO2/FVMQ composite increased by 10 times. FVMQ-based dielectric elastomer had a prime pre-strain ratio around 2X2.Since gelatin had a lot of polar but exhibits poor mechanical property, glycerin was introduced as plasticizer. Glycerin/gelatin composite was prepared with no cytotoxicity. After plasticization, the brittleness of gelatin was weakened and the gelatin showed good elasticity, heat resistance, and mechanical property. Moreover, as the dielectric constant remarkably increased from 6 to 116, the dielectric loss tangent also increased a lot and the volume resistance declined from 1014?·cm sharply to about 106?·cm. The composite would crack at relative low voltage, so the maximum actuated strain was about 3%.