分散介质和温度对纳米二氧化硅胶体剪切增稠行为的影响

Influences of medium and temperature on the shear thickening behavior of nano fumed silica colloids

对分散介质和温度对纳米二氧化硅胶体剪切增稠行为的影响进行了系统研究.用四种液体分散介质(乙二醇,聚乙二醇400,丙二醇,聚丙二醇400)制备的纳米二氧化硅胶体表现出不同的连续剪切增稠或者跳变剪切增稠行为.温度上升降低了分散介质的黏度,进而降低了胶体的表观黏度.剪切增稠的临界黏度与温度的关系符合"Arrhenius"公式的描述.胶体黏度与分散介质黏度的比值用来归一化不同温度下的稳态剪切流变曲线.在低剪切速率的剪切变稀阶段,剪切变稀现象与分散介质黏度没有明显相关性,而与分散介质的化学性质密切相关.在高剪切速率的剪切增稠阶段,分散介质黏度越高,胶体剪切增稠现象越强烈.

The influences of medium and temperature on the shear thickening behavior of silica colloids are investigated. The nano fumed silica colloids in four media （ethylene glycol, polyethylene glycol 400, propylene glycol, and polypropylene glycol 400） exhibit continuous or discontinuous shear thickening behaviors. With the increase of temperature, the medium viscosity decreases, thus the apparent viscosity of colloids decreases. The relationship between the critical viscosity of shear thickening and temperature is well described by the Arrhenius equation. The ratio of viscosity of colloids to medium visocosity is used to scale the steady-shear rheological curves of the colloids under various temperatures. In the shear thinning regime at low shear rate, the form of theological curve is independent of medium viscosity but correlates with the chemical properties of dispersing medium. In the shear thickening regime at high shear rate, a higher medium viscosity results in stronger shear thickening behavior.