A new approach to controlling the viscosity of a coating with a blend of particles with significantly different shapes

Abstract

Purpose

This study aims to introduce a new theoretical approach to blend spherical and non‐spherical particles in a coating to improve its viscosity characteristics.

Design/methodology/approach

Theoretical analysis has been used to modify an existing model developed by this author to apply to a broad range of particle configurations.

Findings

Non‐spherical particles like fibres or discs in a suspension or coating have been found to have three different viscosity response regions. Consequently, the viscosity of suspensions or coatings with these types of particles appears to have two apparent maximums as a function of concentration. Improved viscosity control of coatings have been found to be directly achievable by blending particles with different shapes based on the concentration relative to this first maximum. This optimisation process has been found to be better understood using a new variable which has been described as the “sphericity”, s. The “sphericity”, s, as described in this study has been defined as the relative ratio of the surface to volume fraction for a non‐spherical particle to that of a sphere of equivalent volume.

Research limitations/implications

Experimental data involving monodisperse particles of different configurations is often extremely difficult to obtain. However, the theoretical general concepts can still be applicable.

Practical implications

The model presented in this paper provides practical guidelines to blending pigments with different particle shapes to control the viscosity of coatings and suspensions.

Originality/value

The model presented in this paper provides the first apparent guidelines to control the blending of pigments in coatings and composites with different particle shapes using the “sphericity” of the pigment particle.

Citation

Sudduth, R.D. (2008), "A new approach to controlling the viscosity of a coating with a blend of particles with significantly different shapes", Pigment & Resin Technology, Vol. 37 No. 6, pp. 362-374. https://doi.org/10.1108/03699420810915067