Emulsifier optimization

Mineral acids are used as catalysts, usually in a concentration of 20— 40 wt % and temperatures of 30—60°C. An efficient surfactant, preferably one that is soluble in the acid-phase upon completion of the reaction, is needed to emulsify the a-pinene and acid. The surfactant can then be recycled with the acid. Phosphoric acid is the acid commonly used in the pine oil process. Its mild corrosion characteristics and its moderate strength make it more manageable, especially because the acid concentration is constandy changing in the process by the consumption of water. Phosphoric acid is also mild enough to prevent any significant dehydration of the alcohols formed in the process. Optimization of a process usually involves considerations of acid type and concentration, temperature, surfactant type and amount, and reaction time. The optimum process usually gives a maximum of alcohols with the minimum amount of hydrocarbons and cineoles. 

Already in 1943 M. Schuler [2] described the comparison of the surface-active properties of sodium palmitate with several ether carboxylates based on a constant amount of C atoms. The results showed that with more O bridges the optimal surface activity and emulsifying properties can be achieved at lower temperature, with the detergent properties decreasing and solubility increasing. 

The interest in this type of copolymers is still very strong due to their large volume applications as emulsifiers and stabilizers in many different systems 43,260,261). However, little is known about the structure-property relationships of these systems 262) and the specific interactions of different segments in these copolymers with other components in a particular multicomponent system. Sometimes, minor chemical modifications in the PDMS-PEO copolymer backbone structures can lead to dramatic changes in its properties, e.g. from a foam stabilizer to an antifoam. Therefore, recent studies are usually directed towards the modification of polymer structures and block lengths in order to optimize the overall structure-property-performance characteristics of these systems 262). 

To prepare (true) latices, the monomers are emulsified in water with stirring and addition of emulsifiers, which help stabilize the monomer droplets. The molecular weight of the polymer molecules in the resultant latex can be controlled by the concentration and decomposition rate of added polymerization initiators. The residual monomer content can be reduced by optimizing the polymerization conditions and can also later be eliminated by steam distillation. 

Non-aqueous HIPEs have received even less attention indeed, to date, there have been only two publications dealing with this subject, to the authors knowledge [124,125]. These describe the preparation of highly concentrated emulsions of jet engine fuel in formamide, for use as safety fuels in military applications. The emulsifier system used was a blend of two nonionics, with an optimal HLB value of 12. 

Once the emulsifier is well blended into the carbohydrate melt, the flavoring material is added. An emulsion is formed using a flat bladed turbine type agitator (about 4i inches in diameter). The time of agitation is typically about 5 min. The next step involves pressurization of the extrusion vessel with either nitrogen or carbon dioxide. While others have mentioned pressurization of the vessel for extrusion, Miller and Mutka (8) have optimized this parameter for encapsulation efficiency, they found 7-50 psi most suitable for improving encapsulation efficiency. At pressures above 100 psi, they found some emulsions broke and encapsulation efficiency was very poor. 

In summarizing the work of Miller and Mutka ( ), they have found that optimizing the cook temperature, emulsifier level and extrusion vessel pressurization permits the production of encapsulated flavoring of high flavor load. While the patent claims loadings up to 35%, the practical limit appears to be 16-20%. While this is comparable to the flavor loading typically... 

Gao, P. et al. (2004) Application of a mixture experimental design in the optimization of a self-emulsifying formulation with a high drug loacPharm. Dev. Tech., 9 301-309. 

A comparison of the curves of Figure 7 with those of Figures 4 and 5 clearly shows that the solubility and the emulsifying capacity are not correlated. The optimal conditions for emulsification seem to be at a DH-value where the hydrolysate consists of approximately equal amounts of soluble and insoluble material. Emulsification involves both hydrophilic and hydrophobic groups in the same molecules and it is therefore important that the molecules are not too small. Also, film formation and surface de-naturation play a role, and this also implies that the molecules should not be too small. On the other hand, a certain solubility seems to be necessary for achieving the maximum emulsifying capacity. 

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