论文标题
剪切诱导的调谐和记忆效应杆和球的胶体凝胶
Shear induced tuning and memory effects in colloidal gels of rods and spheres
论文作者
论文摘要
剪切历史在确定胶体凝胶的线性和非线性流变响应中起着重要作用，可用于调整其结构和流动性能。增加胶体颗粒纵横比的增加会降低由于颗粒排除体积的增加而导致的凝胶化的临界体积分数。使用流变学和共聚焦显微镜的组合，我们研究了稳态和振荡性剪切史病史对由长度L和直径D（L/D = 10）分散在11 M CSCL溶液中的硅球和杆形成的胶体凝胶的结构和流变的影响。我们使用MN的非二维梅森号（= f_visc./f_attr。）来比较稳定和振荡性剪切对凝胶粘弹性的影响。我们表明，在中间MN进行预皮后，有吸引力的球体凝胶表现出增强，而有吸引力的杆凝胶表现出弱化。与稳定的预剪切相比，在中间MN，振荡性剪切的凝胶的Rheo成像表明，在中间MN，振荡性的预剪切可诱导凝胶微结构中的大型紧凑型杆簇。我们的研究强调了颗粒形状对剪切后流动和粘弹性下凝胶结构的影响。
Shear history plays an important role in determining the linear and nonlinear rheological response of colloidal gels and can be used for tuning their structure and flow properties. Increasing colloidal particle aspect ratio lowers the critical volume fraction for gelation due to an increase of the particle excluded volume. Using a combination of rheology and confocal microscopy we investigate the effect of steady and oscillatory pre-shear history on the structure and rheology of colloidal gels formed by silica spheres and rods of length L and diameter D (L/D = 10) dispersed in 11 M CsCl solution. We use a non-dimensional Mason number, Mn (= F_visc./F_attr.) to compare the effect of steady and oscillatory pre-shear on gel viscoelasticity. We show that after pre-shearing at intermediate Mn, attractive sphere gel exhibits strengthening whereas attractive rod gel exhibits weakening. Rheo-imaging of gels of attractive rods shows that at intermediate Mn, oscillatory pre-shear induces large compact rod clusters in the gel microstructure, compared to steady pre-shear. Our study highlights the impact of particle shape on gel structuring under flow and viscoelasticity after shear cessation.
