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介电弹性材料是一种新型的电活性聚合物,在电激励下能产生较大的机械变形,可被广泛的用作致动器和传感器。其中3M公司的VHB4910系列丙烯酸薄膜是研究最广泛的介电弹性材料,其关键的电学参数,特别是介电常数,将影响整体的机电耦合性能。然而到目前为止,人们对于VHB4910介电材料介电常数取值的认识尚不统一,特别是频率对介电常数的影响存在着较大分歧,更没有从机理上对其进行分析。基于此现状,利用宽频带介电谱技术通过实验研究了频率(10~(-2)到10~7Hz)对VHB4910介电材料介电性能的影响,发现该材料低频频率依赖性较弱,高频频率依赖性较强,得到材料的低频介电常数为4.8;接着从微观角度出发,分析认为VHB4910介电材料介电常数随频率变化的机理是由于材料偶极子转向极化率随频率变化所致;然后,分析了描述介电材料介电性能的德拜(Debye)方程及Cole-Cole方程的特点,与VHB4910介电材料介电常数实验结果比较发现,Cole-Cole方程更适合描述VHB4910介电材料介电性能;最后,利用实验结果拟合了Cole-Cole方程相关参数,获得了描述VHB4910介电材料介电性能的数学模型。
Dielectric elastic material is a new type of electroactive polymer, which can generate large mechanical deformation under electro-excitation. It can be widely used as an actuator and a sensor. Among them, 3M Company’s VHB4910 series acrylic film is the most widely researched dielectric elastic material. Its key electrical parameters, especially the dielectric constant, will affect the overall electromechanical coupling performance. However, up to now, there is still no consensus on the dielectric constants of VHB4910 dielectric materials. In particular, the influence of frequency on the dielectric constant is quite different, and there is no mechanism to analyze it. Based on the current situation, the influence of frequency (10 ~ (-2) to 10 ~ 7Hz) on the dielectric properties of VHB4910 dielectric was investigated by using broadband dielectric spectroscopy. The results show that the low frequency dependence of the material is weak and high The frequency dependence is strong and the low-frequency dielectric constant of the material is 4.8. Then from the microscopic point of view, the mechanism of the dielectric constant of the VHB4910 dielectric material with frequency is analyzed. The mechanism is that the dipole steering polarizability changes with the frequency Then, the characteristics of Debye equation and Cole-Cole equation describing the dielectric properties of dielectric materials are analyzed. Compared with the experimental results of dielectric constant of VHB4910 dielectric material, the Cole-Cole equation is more suitable for describing VHB4910 Finally, the relevant parameters of Cole-Cole equation are fitted by the experimental results, and the mathematical model describing the dielectric properties of VHB4910 dielectric material is obtained.