Mini-Encyclopedia of Papermaking Wet-End
Part Two: Definitions and Concepts
Papermakers and other technologists involved with slurries, emulsions, and dispersions use the word "stability" in a special way. A slurry, emulsion, or dispersion is said to be colloidally "stable" if it remains as individual particles. By contrast, an unstable mixture coagulates during the time of observation. Colloidal stability is highly desirable when one is considering the transportation and storage of rosin emulsions, TiO2 slurries, etc. However too high a level of colloidal stability in a papermaking system tends to make it difficult to retain fine particles during the formation of the sheet. High stability is favored by such factors as a high uniform zeta potential on the particle surfaces, the presence of surfactant (which may be charged), and the presence of water-loving polymeric loops and tails extending from the surfaces, i.e. steric stabilization. Destabilization of emulsions and dispersions can result from charge neutralization and by polymeric bridging.
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