Project Details
Projekt
Processing of microstructured solid particles based on simple or multiple emulsions by prilling - under consideration of their function preservation for encapsulation of functional components and controlled release
Applicant
Professor Dr.-Ing. Erich J. Windhab
Subject Area
Mechanical Process Engineering
Term
from 2009 to 2016
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 123555429
The encapsulation of functional components (FC) is of broad interest for new product development in the industrial areas of pharmaceuticals, foods, cosmetics, fine chemicals as well as building and packaging materials. Particularly suitable structures for well-defined encapsulation of functional components in emulsion systems have been approved. If such emulsions can be stabilised, encapsulated FC’s can be protected/preserved under storage and further processing conditions as well as controlled release be applied. The reliable stabilisation of complexly structured emulsions can be best achieved by solidification. Consequently to get optimal stability and handling properties of emulsion systems in further production, consumer applications or for storage, it is desirable to bring such emulsions into powder form. A spraying technique coupled with cold solidification of spray drops (prilling) was our preferred choice. In the very successful first project steps (years 1-4) encouraging results concerning functional relationships between (i) geometrical design parameters of two phase spray nozzles, (ii) prilling process parameters (spraying pressure, spraying/prilling temperature, volume flow rate, volume flow rate ratio (fluid/ gas)) and (iii) resulting structural characteristics of spraying drops and prilling powder systems (drop / particle size- and shape distributions, phase morphology and structure preservation) could be achieved. Experimental and CFD simulation based studies provided further details concerning the dynamics of spray lamella breakup and spray drop size / drop-morphology development taking the non Newtonian rheological and structural emulsion properties into account. The complementation of our prilling process by a “post processing” step, an in-vitro gastric disintegration stirred reactor, allowed us to study prill-particle disintegration and coupled release kinetics measurements of functional compounds in a quantitative manner. In the new project step (is 5,6) the knowledge will be further developed in two main directions: (1) Developing a novel spray nozzle-concept, which superimposes pressure and centrifugal acceleration fields thus offering possibilities of a well defined spray filament breakup in the Rayleigh domain. Therefore large filament elongation shall be forced before the Rayleigh breakup proceeds and studied experimentally and by CFD simulation. This would allow to treat the spray particles fluid mechanically gentle and in addition reduce the width of the spray drop/particle size distribution. This lead furthermore to (a) largely improved preservation of encapsulated functional components, (b) better adjustable controlled release and (c) improved powder handling properties and storage behaviour. (2) The thermal prilling conditions (fluid spray - , cooling gas- and product storage temperatures) shall be adapted to the emulsion mass flow rate and the formulation-based melting- and glass transition tempera-ture ranges to be adjusted in such a way that the secondary W-drops in the W/O or O/WO emulsion systems solidify in the glassy state. With this, optimal stability for preservation of encapsulated substances even during longterm storage intervals could be much improved. Possibilities to adjust the kinetics of (i) glass transition in the W-drop phase and (ii) resulting influence on the release kinetics of encapsulated functional compounds will be quantified after various product storage time intervals. For interconnecting the overall processing and product related project results we will complete the derivation of Process-Structure Functions (PSF) and of Structure-Property Functions (SPF), which will finally be coupled to receive the overarching Process-Structure-Property relationships (S-PRO2).
DFG Programme
Priority Programmes
International Connection
Switzerland
