SCI/RSC/SCS conference Cosmetics and Colloids, London 15 February 2005
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online at www.soci.org
Abstract
Selection of emulsifiers and evaluation of emulsion stability is a frequent task. This relates to practical issues like formulation of emulsions, optimization of manufacturing, quality control, and shelf life prediction.
A multisample technique based on analytical centrifugation is presented which allows for an accelerated study of creaming and of separation of oil and water phases. Not only information on the extent of phase separation is provided but also the kinetics are directly measured in-situ. The latter is of great practical importance for estimation of shelf life and in relation to the engineering of separation processes.
Results of investigations on emulsion stability behaviour as function of polarity and composition of nonionic emulsifiers, polarity of the oil phase, preparation conditions and of temperature are presented.
The investigations revealed that the method applied is very suitable for screening purposes, optimization of emulsion manufacturing and that time of investigation and centrifugal acceleration can be adapted to avoid conditions were centrifugal forces are the determining factor for phase separation.
To trace slow destabilizing processes a combination with common accelerated aging tests is the method of choice.
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