介电失配度对沸石电流变液界面极化的影响

The Effect of Dielectric Mismatch Degree on Interface Polarization of Zeolite Electrorheological Liquid

利用介电谱方法研究了NaA沸石/硅油和NaA沸石/煤油两种电流变液的介电行为,测量发现两体系在105Hz处均出现明显的弛豫现象.采用单弛豫Cole-Cole函数拟合各体系的介电参数,结果表明在相同体积分数条件下硅油体系具有较大的介电增量(△ε),且两体系的介电增量与体积分数(φ)均服从△ε=4εmφ的函数关系.通过计算和分析粒子与介质间介电失配程度,阐明了油介质的介电常数(εm)对于沸石电流变液界面极化强度的贡献.此外研究了吸附水对沸石电流变液界面极化的影响,结果发现水的吸附对于体系的△ε值没有影响,但明显降低了弛豫时间,证明吸附水对沸石电流变液的界面极化率具有增强作用.

The dielectric properties of two electrorheological liquid （ERL） systems, NaA zeolite/silicone oil and NaA zeolite/coal oil, were measured by dielectric spectroscopy, and an obvious dielectric relaxation at about 105 Hz can be observed in each of systems. The single relaxation Cole-Cole equation was used to fit the dielectric parameters of the systems, and the results indicated that NaA zeolite/silicone oil possessed larger dielectric increment （？ε）. Furthermore, for both of the two systems, the relationship between the volume fraction （φ） and dielectric increment obeyed the linear function △ε=4εmφ （εm, the permittivity of oil medium）. By means of calculating and analyzing the dielectric mismatch parameter between zeolite particle and oil medium, the contribution of εm to the interface polarization intensity of ERL was clarified. Moreover, the effect of adsorbed water on the interface polarization of zeolite ERL was researched as well. The results indicated that the permittivity of zeolite particle was enhanced and the relaxation time was reduced in the presence of adsorbed water, however, no change was found in △ε of zeolite ERL with adsorbed water. Based on the dielectric mismatch theory, the adsorbed water was proved to be positive to the interface polarization rate of zeolite ERL.