基于单颗粒追踪法研究聚氧化乙烯溶液的微流变特性

Experimental study on microrheological properties of polyethylene oxide solution based on single particle tracking method

基于单颗粒追踪方法研究了不同温度与浓度下聚氧化乙烯(PEO)溶液的微观流变特性。根据广义Stokes-Einstein关系及复杂流体黏弹性理论,利用颗粒追踪技术,对浓度为0.4wt%~1.0wt%的PEO溶液在25℃、35℃和45℃时的微观流变特性进行了测量和分析。研究结果表明,随着被测溶液浓度的增加,探针颗粒的布朗运动受限趋势增大,其中浓度为1.0wt%的PEO溶液在25℃时布朗运动受限最为显著。黏弹特性模量求解结果表明:在实验条件下,PEO溶液的黏性模量(G″(ω))占主导而弹性模量(G′(ω))表现较弱;在相同温度下,黏弹性模量随着溶液浓度上升而增大;随着温度的升高,溶液弹性模量和黏性模量都呈现减小趋势,且弹性模量减小速率大于黏性模量减小速率。均方位移标准差分析表明,基于单颗粒追踪的微流变测量误差随追踪时间的增加呈增大趋势。

The microrheological properties of polyethylene oxide(PEO)solution under different temperatures and different concentrations were studied based on the single particle tracking(SPT)method in this paper.Based on the generalized Stokes-Einstein relationship and the viscoelastic theory of complex fluid,the microrheological properties of PEO dilute solution with concentration of 0.4 wt%~1.0 wt%at 25℃,35℃and 45℃were measured and analyzed by the particle tracking technique.The study results show that the restriction of Brownian motion of the probe particles increases with the increase of the solution concentration.The Brownian motion is most restricted under the concentration of 1.0 wt%and the temperature of 25℃.The solved results of the viscoelastic modulus show that PEO solution is a complex fluid with dominant viscous modulus and weak elastic modulus under the experimental conditions.The viscoelastic modulus of the solution increases with the increase of the solution concentration under the same temperature.Both the elastic modulus(G′(ω))and the viscous modulus(G″(ω))show the decreasing trend with the increase of the temperature,and the decreasing rate of the elastic modulus is larger than that of the viscous modulus.The analysis of MSD standard deviation indicates that the measurement errors show the increasing trend with the increase of the tracking time in the microrheological experiment based on SPT method.