复杂流体的屈服应力及其测定与应用

The Yield Stress of Complex Fluid and Its Determination and Application

稠密的悬浮液以及许多材料都有屈服应力,只有当施加足够大的剪切应力时,它们才会流动。这类屈服应力流体在诸多工业领域和现实生活中广泛存在。中性墨水和打印墨水就是典型的屈服应力流体。这类流体大多是多相多组分的复杂流体,具有复杂多变的多尺度结构,其屈服应力大小通常与许多相互关联的因素有关,特别是与热历史及剪切历史有关,因此屈服应力的准确测定非常困难,从测试理论到测试手段都处于不断发展中。本文综述了屈服应力流体的类别、屈服应力产生的物理机制和流变模型、各种测试方法的优点和局限性,以及屈服应力和触变性测定在墨水研究中的应用,并指出了相关研究中的一些挑战性问题。

Dense suspensions and many other materials have a yield stress,which flow only if a large enough shear stress is exerted on them.Yield stress fluids are widely used in many industrial fields and daily life.Gel inks and printing inks are typical yield stress fluids.This kind of fluids are multiphase multicomponent complex ones,possessing complex and changeable multiscale structures.The yield stress is often associated with many interrelated factors,especially related to the thermal history and shear history,so experimentally the yield stress is very difficult to accurately determine.Both the test theory and the test techniques on the determination of yield stress are developing constantly.This paper reviews the types of yield stress fluids,the physical mechanism of yield stress and rheological models,the advantages and limitations of various rheological testing methods,the application of yield stress and thixotropy measurement in ink research,and points out some relevant challenging problems.