Study On Electrical Properties Of Prestrained Dielectric Elastomer

Dielectric elastomer(DE)is a type of electroactive polymers(EAPs)that converts electric energy into mechanical energy under an applied electric field,and returns to its original shape and volume when the applied electric field disappears.DE has a series of advantages such as fast response,high elastic energy density,low viscoelastic loss,and high electromechanical coupling efficiency.DE has been used in flat loudspeakers,prosthetic organs,and micro-aerocrafts,It has a very wide range of application prospects.The premise that DE obtains large electrostriction is that it must be prestrained,however,the changes in electromechanical properties and microstructure after applying pre-strain to different dielectric elastomers have rarely been reported,this subject has studied the changes of microstructure and electromechanical properties of different DE which were prestrained.Uniaxial prestrain or iso-biaxial prestrain on different DE matrix:After prestrain is applied,the dielectric constant of DE material decreases,and the dielectric loss and dielectric breakdown strength increase due to the orientation behavior.Due to the reduction of the dimension in the thickness direction,the driving voltage of the DE material decreases.Compared with uniaxial prestrain,the number of aligned molecular chains under isoaxial prestrain is larger than that of uniaxial prestrain,so the degree of orientation of Uniaxial prestrain or iso-biaxial prestrain on different DE matrix:After prestrain is applied,the dielectric constant of DE material decreases,and the dielectric loss and dielectric breakdown strength increase due to the orientation behavior.Due to the reduction of the dimension in the thickness direction,the driving voltage of the DE material decreases.Compared with uniaxial prestrain,the number of aligned molecular chains under isoaxial prestrain is larger than that of uniaxial prestrain,so the degree of orientation of the overall biaxial prestrained DE molecular chains is relatively Large,so the dielectric constant under the biaxial prestrain is smaller,and the dielectric loss is greater.The uniaxial prestrain of different acrylonitrile contents of HNBRs:For the same HNBR matrix,when the same uniaxial prestrain rate is applied,the thickness of the HNBR decreases as the prestrain rate increases,so the applied electric field strength increases,so the prestrain can reduce the driving voltage of the material,and at the same time increase its dielectric breakdown strength;the greater the polarity of HNBR,the stronger the polarization ability of molecular chains and the mutual interaction between molecules.The stronger the force,the greater the resistance that the dipole needs to overcome when it rotates under the influence of the external electric field,and therefore the greater the dielectric constant,dielectric strength,and dielectric loss.In this study,infrared dichroism and atomic force microscopy(AFM)methods were used to study the orientation of DE chains:The larger the prestrain rate,the greater the degree of orientation of the DE chains;at the same prestrain,the greater the polarity of the DE material,the lower the degree of orientation of the molecular chains.