Rheology of Titania Pigment Slurry

Titania is one of the most important white pigments currently used in the world with a total annual production of about 6 million [1]. Titania pigment slurry properties are very important for consumer industries such as paints, papermaking and plastics; if aggregates are present, the end-use properties including gloss, brightness, colour hue, opacity and storage stability will be highly affected [2]. Dispersion properties can be greatly improved by addition of a polymeric dispersant [3]. It is therefore very important to understand the interaction between the pigment particles and polymeric dispersants of varying functionality [4]. Pigment dispersion stabilisation is generally provided by two major mech anisms of electrostatic and steric stabilisation repulsion [5, 6]. It is also possible to combine chemical functional groups within the same dispersant molecule to provide both steric and electrostatic stabilization [3]. Abstract: The influence of polymeric dispersants containing different functional groups on the suspension behaviour of titania pigment slurry was investigated. The dispersants chosen were polyacrylic acid and modified polyacrylamides including homo and copolymers modified with carboxylate and/or hydroxyl groups. The pigment slurry rheology was strongly affected by both pH and dispersant chemical groups. The inorganic coating layer on the titania surface is not smooth, but rough or porous. The surface roughness of the pigment can generate additional contribution to the affinity of the dispersants for adsorption.