The Rheological Curve

Abstract

THE shear of a non-Newtonian body, that is, a plastic material or a high-polymeric pseudo-fluid, follows a mechanism showing analogy to that of a true fluid as expressed by the Maxwell equation; but whereas the relaxation of true fluids is purely time-dependent, in the case of non-Newtonian bodies a critical angle of tangential deformation characteristic for each material marks a threshold limit of elastic deformation before relaxation sets in. This elastic limit in plastic materials corresponds to the separation of a secondary aggregate into primary particles and, in the case of pseudo-fluids, to the inception of unkinking of the polymer molecules.