This is an EPSRC-funded project in collaboration with a major Germany-based chemical company.
Wax dispersions are applied in many formulations, e.g. in paints and lacquers, printing inks, floor, furniture and automobile polish, paper coatings, foods, cosmetics etc. Such dispersions set application properties such as scratch, rub and dirt resistance, water repellency, moisture and grease barrier, gloss, surface smoothness or a tailored release of actives. This requires tailor-made product properties, especially colloidal properties like spherical and individual particles as well as a precise adjustment of the particle size distribution and rheology. In principle, this can be realized in melt emulsification processes. Melt emulsification is based on preparing a wax-in-water-emulsion at temperatures above the melting point of the wax phase. After emulsification the droplets are cooled down. Ideally individual solid particles of spherical shape are formed.
However, during liquid-solid phase transition other scenarios have also been observed in earlier experiments:
1. Full coalescence of large droplets due to unsuitable emulsifiers
2. Partial coalescence leading to egg-shaped particles
3. Formation of aggregates or flock
The underlying mechanisms are not fully understood up to date. I.e., in reality product development for melt emulsions is usually based on time- and cost-consuming trial-and-error-approaches. The goal of this project is to get a deeper understanding of wax hardening in melt emulsification for a faster and more target-oriented product development. This will be realized via the discrimination of the basic mechanisms and the development of a decision tree that will enable for a thorough selection of process and product parameters in melt emulsification. Herewith, the stabilization of products that couldn’t be stabilized so far will be possible and the time to market can be reduced.
The project will involve aspects from various disciplines of chemical engineering:
• Colloid chemistry
• Wax crystallization
• Interfacial and emulsion characterization
• Heat and mass transfer
• Process development
Eligibility: to qualify for an EPSRC studentship candidates must be a UK or EU national and hold the minimum of at least a 2(i) or a 2(ii ) plus an MSc in a relevant discipline. If interested in the above position please send your c.v. to Dr Richard Greenwood: [email protected]