The Structure and Rheology of Complex Fluids PDF

PREFACE

Every elementary school pupil is taught that there are three states of matter: solid, liquid, and gas. To these might be added "plasma," which exists at extremely high temperatures, or the "Bose-Einstein condensate," at extremely low ones. However, one needn't resort to superfrigid or superhot extremes to find states of matter that challenge the ordinary division into solids, liquids, and gases. Such everyday substances as mayonnaise or window glass will do the trick.

While it is true that the classical definition of "liquid" as opposed to "solid" provides a basis for deciding whether a substance is a solid or a liquid, the classical definition is inadequate not only for many everyday purposes, but for engineering ones as well. According to the classical definition, a "fluid" is any substance that deforms continuously under the application of an arbitrarily small shearing stress. By this definition, mayonnaise is a solid, since it holds its shape against gravity, while window glass is a liquid (!), since it creeps, albeit ever so slowly, against forces even much weaker than gravity. Clearly, for many workaday uses, in the home and on the factory floor, the classical definition is inadequate.