| Dielectric Elastomer（DE）is an electroactive polymer which surface charge will change as the shape or size of the material changes.A device consisting of a DE film and a flexible electrode coated on either side can be used as a driver by deforming under electrical stimulation.In addition,it has broad application potentials in artificial muscles,energy collectors,tidal power generation and other fields for its ability to convert mechanical energy into electrical energy as a sensor or energy collector.Although DE materials have unique advantages such as high energy density,high conversion efficiency,low cost and direct coupling with various energy sources without intermediate conversion,they still face great obstacles when applied to actual components due to problems such as low breakdown voltage and easy aging failure.With its elasticity and extremely fast response speed,silicone rubber can maintain its inherent flexibility,elasticity and stability in a wide temperature range,as well as tolerance to high electric field strength and other advantages,which is considered to be the most commercially valuable product in DE applications.In this paper,taking dielectric elastomer generator as the application target and dielectric elastomer of silicone rubber as the research object,the influences of the chemical structure of silicone rubber and the addition of inorganic filler on its dielectric and mechanical properties were deeply studied,at the same time,the effect of pre-tensile in application process on its mechanical properties and the mechanism of mechanical failure were also analyzed.The research results will provide important scientific basis for the application of silicone rubber dielectric elastomer in the preparation of dielectric elastomer generator,which have significant value to promote the practical application of silicone rubber in dielectric elastomer.The specific content includes the following four parts:（1）The effect of the degree of crosslinking on the mechanical and dielectric properties of homogeneous silicone rubber was studied.Firstly,the effects of different crosslinking agent ratio on the mechanical and dielectric properties of the commercial product DC186 silicone rubber were studied.Then,the effects of the proportion of different molecular weight silicone oil components on the mechanical properties and dielectric properties of the silicone rubber were studied in detail using self-prepared two-component RTV silicone rubber,and the most suitable matrix formula with good comprehensive properties was determined.（2）The dielectric filler was synthesized by surface modification of the nano-Si O2 filler with 3-mercaptopropyl trimethoxysilane（MPTMS）containing polar group sulfhydryl and then added to the RTV silicone rubber matrix.The introduction of polar silane coupling agent can not only promote the dispersion of inorganic filler in RTV silicone rubber,but also improve the dielectric properties of DE material.The effects of content and surface structure of filler on the mechanical and dielectric properties of the composites were studied and compared with the commercial product HY-625 silicone rubber with different Si O2 content.The results show that 2-MPTMS@Si O2/PDMS composite has the best application performance with 8 wt%modified filler content,of which dielectric constant can reach 4.29,dielectric loss is as low as 0.07,and breakdown strength can reach 75.69 k V/mm.（3）The effect of pre-tensile on the structural orientation,mechanical and electrical properties of DE material was studied,and the mechanism of pre-tensile was also preliminary analyzed.DC186 silicone rubber,HY-625 silicone rubber and MPTMS@Si O2/PDMS composites were selected as samples with different structures and the enhancement of pre-tensile degree on the dielectric properties and breakdown strength were studied.After comparing the mechanical and electrical responses of different samples with same degree of pre-tensile,it is found that the enhanced effect of pre-tensile on the dielectric elastomer composite material containing filler material is more significant.（4）According to the possible failure mode of the silicone rubber dielectric elastomer in the application process,the thermal aging,cyclic tensile recovery testing hysteresis loss and creep performance test were carried out.It is found that the high crosslinking degree of DE material and the appropriate particle filling content are conducive to the dielectric elastomer in the application process to maintain the performance stability. |
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