Relationship Between Electromechanical Properties And Power Grneration Properties Of Dielectric Elastomer Materials Under Equibiaxial Tensile Mode

Dielectric elastomer generator（DEG）is a new type of generator that uses the tensile variable capacitance of dielectric elastomer（DE）to generate electricity.It can convert the mechanical work input in reciprocating motion into electrical energy,so as to collect electrical energy from low-frequency motion sources such as human motion energy,wave energy and wind energy.The research shows that the power generation performance of DEG（single cycle power generation,energy density and electromechanical conversion efficiency）is affected by many factors,such as tensile mode,experimental circuit and electromechanical properties of materials.At present,most of the relevant research is based on a commercial polyacrylate material.The effects of tensile mode and experimental circuit on the power generation performance of the material are studied through simulation.Common stretching modes include uniaxial stretching,conical stretching,equibiaxial stretching and inflatable stretching,in which the maximum material power generation performance can be obtained under equibiaxial stretching.Other work has focused on the preparation of new high-performance power generation materials.However,up to now,the relationship between the electromechanical properties of materials and the power generation properties under equibiaxial tensile mode is not clear,so the preparation direction of high-performance power generation materials is still unclear.It has been reported that materials with low conductivity and high elongation at break are the premise of power generation,and under the condition of certain bias voltage,the power generation performance of DEG is mainly affected by constant elongation stress and dielectric constant.Therefore,this subject intends to study the coupling relationship between the electromechanical properties（including constant tensile stress and dielectric constant）of materials and the power generation performance of DEG under equibiaxial tensile mode.The tensile crystalline butyl bromide rubber（BIIR）and non tensile crystalline cis-1,4-polybutadiene rubber（BR）with carbon chain as the main chain and non tensile crystalline silicone rubber（SiR）with silicon oxygen bond as the main chain are selected as the de matrix respectively,a series of samples with200%constant tensile stress(M₂₀₀)and dielectric constant were prepared under the condition of meeting the requirements of power generation（ε）.Through the characterization of its microstructure,mechanical properties,electrical properties and power generation properties,the influence relationship between the electromechanical properties of dielectric elastomer materials and power generation properties in equibiaxial tensile mode is clarified.The research contents and conclusions of this subject are as follows:In the equibiaxial tensile mode,the single cycle power generation of BIIR based materials increases with the increase of the compositeε,but is less affected by M₂₀₀.For the same material,the single cycle power generation increases with the increase of preset strain and applied bias voltage,but the maximum single cycle power generation is obtained at the moderate strain（150%）,not at the maximum strain（200%）.The energy density is basically consistent with the law of single cycle power generation.Increasing the dielectric constant of the material or reducing M₂₀₀can improve the electromechanical conversion efficiency.In the equibiaxial tensile mode,the single cycle power generation and energy density of BR based materials increase with the increase of the compositeε.The sameεbut different M₂₀₀composites show similar single cycle power generation and energy density.For the same composite,increasing the preset strain or external bias voltage can increase the single cycle power generation,but the maximum single cycle power generation of BR based materials is obtained at 100%strain rather than at the maximum strain（150%or 200%）.Electromechanical conversion efficiency is affected byεand M₂₀₀,that is,the electromechanical conversion efficiency is positively correlated withεand negative correlated with M₂₀₀.In the equibiaxial tensile mode,without considering the leakage,the single cycle power generation and energy density of SiR based material are directly proportional to theε,applied bias voltage and preset strain,and are basically not affected by M₂₀₀.However,the maximum single cycle power generation of SiR based materials is obtained at 100%strain,not at the maximum strain（200%）.The electromechanical conversion efficiency increases with the increase of dielectric constant and decreases with the increase of M₂₀₀.The tensile crystallization characteristics of BIIR based materials lead to a significant increase in the input mechanical work under higher biaxial strain（100%-150%）.Therefore,compared with BR based materials,the electromechanical conversion efficiency of BIIR materials decreases more obviously with strain.In the case of similar single cycle power generation,at100%strain,the electromechanical conversion efficiency of BIIR based and BR based materials are 7.31%and 6.14%respectively,and the conversion efficiency of BIIR based materials is higher.However,at 150%strain,the electromechanical conversion efficiency of BIIR based and BR based materials are 3.07%and 3.55%respectively,at which the electromechanical conversion efficiency of BR materials is higher.Compared with BR based materials with carbon bond as the main chain,the main chain of SiR based materials is mainly silicon oxygen bond.The molecular chain of the latter is more flexible,the constant elongation stress is lower and the viscosity loss is smaller.Therefore,the maximum electromechanical conversion efficiency of the former is only 11.61%and that of the latter is 34.07%.The results show that the selection of lower M₂₀₀matrix is conducive to further improve the electromechanical conversion efficiency.