Fabrication and optimization of dielectric elastomer actuator using MWCNT-CB/PDMS composite electrodes
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摘要: 介电弹性体驱动器(DEA)的柔性电极发挥着产生电场和约束介电母体形变的重要作用。本文以一维的多壁碳纳米管(MWCNT)和零维的导电炭黑(CB)为共同导电填料,设计浇注了一系列不同尺寸,不同力学、电学性能的聚二甲基硅氧烷(PDMS)复合电极膜(MWCNT-CB/PDMS)。将电极膜粘附在聚氯乙烯凝胶膜的两侧表面,导入脉冲高压电信号,获得一系列电驱动行为变化的新型介电聚合物驱动器。驱动性能测试结果表明:电极覆盖率的增加有利于DEA位移输出;电极厚度的增加限制了DEA的位移输出;随着MWCNT掺杂量的增加,位移输出呈现先增后减的趋势。正交实验结果表明:MWCNT掺杂量对DEA的驱动位移有显著的影响,电极覆盖率和厚度有高度显著的影响;最优组合下,驱动器的位移输出为1.71 mm。Abstract: Flexible electrode of dielectric elastomer actuator (DEA) plays important roles in generating electric fields and constraining dielectric matrix deformation. By using one-dimensional multi-wall carbon nanotubes (MWCNT) and zero-dimensional conductive carbon black (CB) as co-conductive fillers, a series of polydimethyl siloxane (PDMS) composite electrode films (MWCNT-CB/PDMS) were designed with varying size, mechanical and electrical properties. The electrode films were adhered to the lateral surfaces of a polyvinyl chloride gel matrix film and imported into a pulsed high-voltage signal to obtain novel dielectric polymer actuators with various electromechanical behaviors. Tests of electromechanical properties reveal that, the increase of electrode coverage is beneficial to DEA’s strain, the increase of electrode thickness hampers its strain, while the strain exhibits an initial increase following decrease trend with increasing MWCNT loading. Orthogonal experiment show that, the MWCNT loading has a significant effect on the displacement output, while the electrode coverage and thickness present high-level significances to the displacement output; under the optimal condition, the displacement output of DEA is 1.71 mm at maximum.
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图 3 电极膜和母体膜的相关物性表征:(a) 不同MWCNT掺杂后多壁碳纳米管-导电炭黑/聚二甲基硅氧烷(MWCNT-CB/PDMS)复合电极膜。MWCNT-CB/PDMS复合膜的应力-应变曲线;(b) MWCNT-CB/PDMS复合膜弹性模量;(c) PVC母体膜的应力-应变曲线;(d) MWCNT-CB/PDMS复合膜的方块电阻
Figure 3. Related physical characterizations of the matrix and electrode films. (a) typical stress-strain curves for the multi-wall carbon nanotubes-conductive carbon black/polydimethyl siloxane (MWCNT-CB/PDMS) electrode films with different MWCNT loadings; (b) their calculated Young’s moduli; (c) stress-strain curves for the PVC matrixes; (d) sheet resistances for the MWCNT-CB/PDMS composite electrode films.
图 5 不同驱动电场下的DEA输出位移演变。PVC复合膜中DOP∶PVC的质量比为3∶1,PDMS电极含4wt% MWCNT,驱动信号为1.0 Hz、占空比为0.5的方波。
Figure 5. Evolution of DEA’s outputted displacement with electronic field. The PVC matrix composite contained 75wt% DOP, and the PDMS electrode contained 4 wt % MWCNT. The driven signal was square wave with 1.0 Hz frequency and 50 % duty ratio.
图 6 位移输出性能比较:不同MWCNT掺杂量、电极覆盖率、电极厚度下的位移响应曲线(a、d、g);局部位移图(b、e、h);具体的位移输出数据(c、f、i)。(a-c)中,电极厚度为50 μm,覆盖率为65%;(b-f)中,MWCNT的质量份数为4wt%,电极厚度为50 μm;(g-i)中,MWCNT的质量份数为4wt%,覆盖率为65%。驱动信号均为1.0 Hz、占空比为0.5的方波。
Figure 6. Comparison of displacement output: displacement curves for different MWCNT loadings (a, d, g), coating ratio (b, e, h), and thickness (c, f, i); for DEA of a-c, the electrode thickness is 50μm, and the coating ratio is 65%; for DEA of b-f, the electrode thickness is 50μm, and the MWCNT loading is 65%; for DEA of g-i, the MWCNT loading is 65%, and the coating ratio is 65%. The driven signal was square wave with 1.0 Hz frequency and 50 % duty ratio
表 1 DEA相关参数与性能
Table 1. DEA-related parameters and properties
Mass fraction of
MWCNT/wt%Thickness/
mmElongation at
break/%Tensile strength/
MPaElastic modulus/
MPaElectrode resistance/
(Ω·sq−1)Electric conductivity /
(s·cm−1)0 0.306 326 1.118 0.612 1143 0.026 2 0.391 308 1.325 0.892 573 0.059 4 0.390 280 1.533 1.155 293 0.121 6 0.317 254 1.709 1.529 147 0.250 8 0.314 224 1.843 4.032 56 0.239 表 2 DEA电驱动响应数据
Table 2. DEA’s electromechanical response data
Mass fraction of MWCNT/wt% Displacementa
/mmCoverage ratio/% Displacementb
/mmThickness
/mmDisplacementc
/mm0 0.99 35 0.87 0.052 1.41 2 1.24 50 1.15 0.101 1.22 4 1.41 65 1.39 0.153 1.02 6 1.31 80 1.61 0.209 0.88 8 1.12 95 1.71 0.252 0.65 Notes: a The electrode coverage was 65%, the thickness was 50% μm, the doping amount of MWCNT was changed; b The doping amount of MWCNT is 4wt%, the electrode thickness was 50 μm, the electrode coverage was changed; c The doping amount of MWCNT was 4wt%, the electrode coverage was 65%, and the electrode thickness was changed. 表 3 正交实验水平因素表
Table 3. Orthogonal experimental level factors
Factor A (MWCNT doping/wt%) C (Coverage ratio/%) D (Thickness/mm) 1 0 95 0.052 2 2 80 0.101 3 4 65 0.153 4 6 50 0.209 5 8 35 0.252 表 4 正交实验方法与设计
Table 4. Experimental design of an orthogonal array method
Experimental group A B C D(Blank group) Xi(Displacement
/mm)1 1 1 1 1 1.42 2 1 2 2 2 1.09 3 1 3 3 3 0.75 4 1 4 4 4 0.36 5 1 5 5 5 0.28 6 2 1 2 3 1.56 7 2 2 3 4 1.13 8 2 3 4 5 0.69 9 2 4 5 1 0.46 10 2 5 1 2 0.87 11 3 1 3 5 1.49 12 3 2 4 1 1.05 13 3 3 5 2 0.65 14 3 4 1 3 1.15 15 3 5 2 4 0.79 16 4 1 4 2 1.14 17 4 2 5 3 0.83 18 4 3 1 4 1.31 19 4 4 2 5 0.97 20 4 5 3 1 0.53 21 5 1 5 4 0.92 22 5 2 1 5 1.36 23 5 3 2 1 0.99 24 5 4 3 2 0.61 25 5 5 4 3 0.75 Ij 3.91 6.53 6.11 4.46 IIj 4.71 5.47 5.41 4.37 IIIj 5.13 4.38 4.51 5.04 IVj 4.77 3.55 3.98 4.49 Ⅴj 4.63 3.21 3.14 4.78 Rj 1.23 3.32 2.97 0.67 Sj 0.16 1.50 1.09 0.06 表 5 正交实验方差分析结果
Table 5. Orthogonal experimental ANOVA results
Variance source Sum of deviation squares Degree of freedom Sum of squares of average deviation F value Significance A 0.16 4 0.04 2.97 ** B 1.50 4 0.38 27.49 *** C 1.09 4 0.27 19.87 *** D 0.06 4 0.02 1.15 Notes: ** means that the factor has a significant impact on the experiment results, *** means that the factor has a highly significant impact on the experiment results. -
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