Emulsifier structure

The effect of emulsifier structure on the electrodeposition of cationic latexes has been investigated. The electrocoating performance of these systems can be correlated with the reducibility of the emulsifier. 

Figure 4. Current-time curves illustrating the effect of emulsifier structure on current cutoff. (A) p-nitrooenzyl-methyldodecylsulfonium chloride (B) p-fiuorobenzyldi-methyldodecylammonium chloride.

Various other effects of emulsifiers have been observed in particular systems but systematic studies of these effects in relation to emulsifier structure have not yet been undertaken. 

Aerosol AT solutions (sodium dioctylsulfosuccinate) ftloUed according to both dynamic (drop formation period 2 sec) and static (drop formation period 2 min) values. The difference in the ape of the isotherms clearly indicates the significance of the time of surface formation for effective emulsifier edsorption and stabilization at the interface. Apart from the emulsifier structure, the process may depend on the difference in polarity between the contiguous phases,... 

Emulsifier Structure and Emulsifier Chemistry One of the key factors to successfully produce a stable lipid emulsion is the addition of a suitable emulsifier. Although a detailed discussion of emulsifiers and emulsifier chemistry is beyond the scope of this chapter, a brief introduction to emulsifiers/surfactants seems appropriate. Surfactants are surface-active compounds that can adsorb to appropriate interfaces once dispersed in a solvent (41 8). Emulsifiers are those surfactants that are specifically used to stabilize emulsions. Surfactants are... 

Figure 5. Effect of Emulsifier Structure on Reaction Time...

Many emulsifier variations have been used during the course of this research effort. The effect of emulsifiers has been observed on numerous properties of the emulsions generated. A study was initiated to determine the effect of emulsifier structure on the autoxidation rate of reaction. Figure 5 represents the oxygen pressure variation during successive reactions as a function of the time required to reach a densely crosslinked state. The Gafac RE-960 system is dramatically slower relative to the autoxidation rate when T-Det and dodecyl sodium sulfate or Igepal CO-850 and dodecyl sodium sulfate surfactants are employed. 

These systems are ako called Winsor (W) microemukion types I, II, and III, respectively. Formation of each of these systems depends on the conditions and composition of the phases and each type can be formed from another type by varying one or more of the parameter(s) of the system (salt, coemukifier, emulsifier structure... 

Food Emulsifiers Structure-Reactivity Relationships, Design, and Applications... 

The structure of cholic acid helps us understand how bile salts such as sodium tauro cholate promote the transport of lipids through a water rich environment The bot tom face of the molecule bears all of the polar groups and the top face is exclusively hydrocarbon like Bile salts emulsify fats by forming micelles m which the fats are on the inside and the bile salts are on the outside The hydrophobic face of the bile salt associates with the fat that is inside the micelle the hydrophilic face is m contact with water on the outside... 

Foams may be produced from these resins by addition of 65 35 TDI, water, a catalyst, an emulsifier, a structure modifier and paraffin oil which helps to control pore size and prevents splitting of the foams. 

Amongst the catalysts described in the literature may be mentioned dimethylbenzylamine, dimethlylcyclohexylamine, diethylaminoethanol, Walkylmorpholines and the adipic acid ester of A-diethylaminoethanol. A number of proprietary products of undisclosed composition have also been successfully employed. Emulsifiers include sulphonated castor oil and structure modifiers such as ammonium oleate and silicone oils. 

The function of emulsifier in the emulsion polymerization process may be summarized as follows [45] (1) the insolubilized part of the monomer is dispersed and stabilized within the water phase in the form of fine droplets, (2) a part of monomer is taken into the micel structure by solubilization, (3) the forming latex particles are protected from the coagulation by the adsorption of monomer onto the surface of the particles, (4) the emulsifier makes it easier the solubilize the oligomeric chains within the micelles, (5) the emulsifier catalyzes the initiation reaction, and (6) it may act as a transfer agent or retarder leading to chemical binding of emulsifier molecules to the polymer. 

One of the most important characteristics of the emulsifier is its CMC, which is defined as the critical concentration value below which no micelle formation occurs. The critical micelle concentration of an emulsifier is determined by the structure and the number of hydrophilic and hydrophobic groups included in the emulsifier molecule. The hydrophile-lipophile balance (HLB) number is a good criterion for the selection of proper emulsifier. The HLB scale was developed by W. C. Griffin [46,47]. Based on his approach, the HLB number of an emulsifier can be calculated by dividing... 

A strain of Acinetobacter calcoaceticus produces an unusual polysaccharide called emulsan. It is a complex polymer comprising about 15% fatty acyl esters and 20% protein. This structure enables it to act as an emulsifying agent, stabilising hydrocarbon/water emulsions at very low concentrations (0.1-1.0%). This property,... 

Formation of emulsions of the oil-in-water or water-in-oil type depends mainly on the hydrophilic-lipophilic balance (HLB) of the emulsifier. Phosphate esters with their various molecular structures can be adjusted to nearly every HLB value desired. Therefore they are able to meet nearly all of demands in this field. 

Emulsion polymerization is the most important process for production of elastic polymers based on butadiene. Copolymers of butadiene with styrene and acrylonitrile have attained particular significance. Polymerized 2-chlorobutadiene is known as chloroprene rubber. Emulsion polymerization provides the advantage of running a low viscosity during the entire time of polymerization. Hence the temperature can easily be controlled. The polymerizate is formed as a latex similar to natural rubber latex. In this way the production of mixed lattices is relieved. The temperature of polymerization is usually 50°C. Low-temperature polymerization is carried out by the help of redox systems at a temperature of 5°C. This kind of polymerization leads to a higher amount of desired trans-1,4 structures instead of cis-1,4 structures. Chloroprene rubber from poly-2-chlorbutadiene is equally formed by emulsion polymerization. Chloroprene polymerizes considerably more rapidly than butadiene and isoprene. Especially in low-temperature polymerization emulsifiers must show good solubility and... 

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 keep their various ingredients mixed together uniformly, shampoos also contain emulsifiers whose structures include hydrophobic and hydrophilic components. Our inset shows the structure of panthenol, one such... 

Emulsifiers assist the stabilizing hydrocolloids in controlling crystal structure. They accentuate the function of the homogenizer in reducing the size of the fat globules. They also reduce the interfacial tension between the fat and water phases of the mix. The result is smaller ice particles and air cells when the mix is frozen and a smoother and creamier finished product. 

In the production of crude oil, the greatest part of the crude oil occurs as a water-in-oil emulsion. The composition of the continuous phase depends on the water/oil ratio, the natural emulsifier systems contained in the oil, and the origin of the emulsion. The natural emulsifiers contained in crude oils have a complex chemical structure, so that, to overcome their effect, petroleum-emulsion demulsifiers must be selectively developed. As new oil fields are developed, and as the production conditions change at older fields, there is a constant need for demulsifiers that lead to a rapid separation into water and oil, as well as minimal-residual water and salt mixtures. 

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