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Attainment of emulsion properties on design a typical case of formulation engineering

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Emulsions properties depend upon the combined effects of physico-chemical formulation, composition and stirring features used during the emulsification protocol. It is shown that according to the currently available know-how, the emulsification process characteristics can be set on a formulation-composition map and can be translated into process design and engineering information. Two typical examples are discussed.
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... This is essentially due to the fact that engineers involved in mixing-stirring technology do not know or do not care about physico-chemical formulation, whereas chemists or physical-chemists are not often concerned by hydrodynamics and mixing issues. As a consequence none of the current approaches is satisfactory for the emulsion maker, and all are likely to hinder the effects of coupled and competitive phenomena, although these have been recently reported to be determinant in many instances [3][4]. ...
... It is now well established that as formulation is changed from hydrophilic (HLD < 0) to lipophilic (HLD > 0) conditions, whatever the variable used to produce the change in HLD, the emulsion inverts from oil-in-water (O/W) to water-in-oil (W/O) a change which is known as Bancrofft's rule [35][36]because it essentially corresponds to what was enounced almost one century ago. It is now well accepted that the emulsion properties change according to Figure 1scheme that sum up scores of experimental data [3][4][5][6][7][8][9][10][11]. The emulsion drop size is the result of a dynamic equilibrium between two opposite effects: on the one hand those which tend to decrease the drop size, e. g., shearing or stirring, and on the other hand those which favor the coalescence between drops [2, 37]. ...
... This is essentially due to the fact that engineers involved in mixing-stirring technology do not know or do not care about physico-chemical formulation, whereas chemists or physical-chemists are not often concerned by hydrodynamics and mixing issues. As a consequence none of the current approaches is satisfactory for the emulsion maker, and all are likely to hinder the effects of coupled and competitive phenomena, although these have been recently reported to be determinant in many instances34. ...
... It is now well established that as formulation is changed from hydrophilic (HLD < 0) to lipophilic (HLD > 0) conditions, whatever the variable used to produce the change in HLD, the emulsion inverts from oil-in-water (O/W) to water-in-oil (W/O) a change which is known as Bancrofft's rule3536 because it essentially corresponds to what was enounced almost one century ago. It is now well accepted that the emulsion properties change according toFigure 1 scheme that sum up scores of experimental data34567891011. The emulsion drop size is the result of a dynamic equilibrium between two opposite effects: on the one hand those which tend to decrease the drop size, e. g., shearing or stirring, and on the other hand those which favor the coalescence between drops [2, 37]. ...
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