Ceramics-Silikáty 48 (3) 93-99 (2004)

RHEOLOGY OF CERAMIC SUSPENSIONS WITH ORGANIC OR BIOPOLYMERIC GELLING ADDITIVES - PART 1. THEORY OF LINEAR VISCOELASTICITY

E. Gregorová, W. Pabst, J. Štětina

Many new ceramic shaping methods, in particular those involving casting of ceramic suspensions into non-porous molds, are based on gelation steps and sol-gel transitions. For these systems, usually containing an aqueous phase with organic or biopolymeric ingredients, rotational viscometry is insufficient and oscillatory shear rheometry becomes an indispensible tool to characterize the rheological changes during processing, particularly the body-formation step. In this introductory paper, the theory of linear viscoelasticity is summarized for ceramic scientists and engineers to the degree necessary for a basic understanding of the rheological behavior of sol-gel systems and gelation processes. This shortcut should provide a handy reference for subsequent papers dealing with the rheology of ceramic suspensions containing carrageenan and other organic or biopolymeric ingredients.

Keywords: Linear viscoelasticity, Storage modulus, Loss modulus, Phase angle, Complex viscosity