Olive oil + Water + Asq gives:
a- Emulsion.***
b- Solution.
c- Suppositories.
-----------------
The emulsion is an integrated liquid of at least two other liquids. One of them is emulsified in the other, which is in greater quantity. The one that is emulsified is called the dispersed phase, and the one that contains it is a continuous phase.
Since emulsification is not an exact science, certain generalizations based on the experience of testing are necessary. Emulsions do not always reach equilibrium in a short time, and as a consequence they frequently experience alterations over time. In such circumstances it is to be recognized that generalizations are not rigorous laws, but must be considered in relation to the kind of product in question.
Definition:
The emulsion is a two-phase system consisting of two partially Miscible Liquids, one of which is dispersed in the other in the form of globules. The dispersed, discontinuous or internal phase is the disintegrated fluid in globules. The surrounding liquid is the continuous or external phase. The suspension is a two-phase system very similar to the emulsion, whose dispersed phase is a solid.
Foam is a two-phase system similar to emulsion, in which the dispersed phase is a gas. Aerosol is the opposite of foam: air is the continuous phase and liquid is the dispersed phase. An emulsifying agent is a substance that is usually added to one of the phases to facilitate the formation of a stable dispersion.
Industry is more interested in the emulsification of oil and water. The emulsions of oil and water (oleo-aqueous) have the oil as a dispersed phase in the water, which is the continuous phase. In hydrooleous or water-in-oil emulsions, water is dispersed in oil, which is the external phase. There are occasions when the type of emulsion is not clearly defined, since the internal and external phase, instead of being homogeneous, contains portions of the opposite phase; An emulsion of this kind is called a dual emulsion.
Properties of Emulsions:
Its most important properties are its usefulness and the aspect that they offer to the consumer, be it the industrialist or the final consumer. The properties that are more obvious and usually more important are: ease of dilution (usually with water, even if it is with some selective solvent), viscosity, color, stability and, if the emulsion is formed in the place where it is used Finally, its ease of training. For a given type of emulsification, these properties depend on the following:
- The properties of the continuous phase
- The relationship between internal and external phase
- The particle size of the emulsion
- The relationship between the continuous phase and the particles (including ionic charges)
- The properties of the discontinuous phase.
In a given emulsion, the properties depend on the liquid that forms the external phase, or on whether the emulsion is oleo-aqueous or hydroleous. The type of emulsion that results depends:
- Of the type, quantity and quality of the emulsifier
- Of the reason between ingredients
- Of the order in which the ingredients are added when mixed.
The Dispersability (solubility) of an emulsion is determined by the continuous phase; If the continuous phase is Water-soluble, the emulsion can be diluted with water, if the continuous phase is oil-soluble, the emulsion can be dissolved in oil. The ease with which an emulsion can be dissolved can be increased if the viscosity of the emulsion is reduced.
Viscosity:
The Viscosity of an emulsion when there is continuous excess phase is virtually the viscosity of said phase. Increasing the proportion of the internal phase increases the viscosity of the emulsion to a point where the emulsion ceases to be liquid. When the volume of the internal phase exceeds that of the external phase, the emulsion particles agglomerate and the apparent viscosity is partially structural viscosity.
Theoretically, the maximum volume, which can be occupied by uniform spherical particles in the dispersed phase of an emulsion is 74% of the total volume. Emulsions having up to 99% of the internal phase can be prepared. In these cases there is considerable deformation compared to the ordinary particle shape of the dispersed phase.
The viscosity of an emulsion can be regulated as follows:
- To reduce viscosity
- The proportion of the continuous phase is increased,
- The viscosity of the continuous phase is reduced,
In suspensions, surface activity agents are added to increase lubrication.
a- Emulsion.***
b- Solution.
c- Suppositories.
-----------------
The emulsion is an integrated liquid of at least two other liquids. One of them is emulsified in the other, which is in greater quantity. The one that is emulsified is called the dispersed phase, and the one that contains it is a continuous phase.
Since emulsification is not an exact science, certain generalizations based on the experience of testing are necessary. Emulsions do not always reach equilibrium in a short time, and as a consequence they frequently experience alterations over time. In such circumstances it is to be recognized that generalizations are not rigorous laws, but must be considered in relation to the kind of product in question.
Definition:
The emulsion is a two-phase system consisting of two partially Miscible Liquids, one of which is dispersed in the other in the form of globules. The dispersed, discontinuous or internal phase is the disintegrated fluid in globules. The surrounding liquid is the continuous or external phase. The suspension is a two-phase system very similar to the emulsion, whose dispersed phase is a solid.
Foam is a two-phase system similar to emulsion, in which the dispersed phase is a gas. Aerosol is the opposite of foam: air is the continuous phase and liquid is the dispersed phase. An emulsifying agent is a substance that is usually added to one of the phases to facilitate the formation of a stable dispersion.
Industry is more interested in the emulsification of oil and water. The emulsions of oil and water (oleo-aqueous) have the oil as a dispersed phase in the water, which is the continuous phase. In hydrooleous or water-in-oil emulsions, water is dispersed in oil, which is the external phase. There are occasions when the type of emulsion is not clearly defined, since the internal and external phase, instead of being homogeneous, contains portions of the opposite phase; An emulsion of this kind is called a dual emulsion.
Properties of Emulsions:
Its most important properties are its usefulness and the aspect that they offer to the consumer, be it the industrialist or the final consumer. The properties that are more obvious and usually more important are: ease of dilution (usually with water, even if it is with some selective solvent), viscosity, color, stability and, if the emulsion is formed in the place where it is used Finally, its ease of training. For a given type of emulsification, these properties depend on the following:
- The properties of the continuous phase
- The relationship between internal and external phase
- The particle size of the emulsion
- The relationship between the continuous phase and the particles (including ionic charges)
- The properties of the discontinuous phase.
In a given emulsion, the properties depend on the liquid that forms the external phase, or on whether the emulsion is oleo-aqueous or hydroleous. The type of emulsion that results depends:
- Of the type, quantity and quality of the emulsifier
- Of the reason between ingredients
- Of the order in which the ingredients are added when mixed.
The Dispersability (solubility) of an emulsion is determined by the continuous phase; If the continuous phase is Water-soluble, the emulsion can be diluted with water, if the continuous phase is oil-soluble, the emulsion can be dissolved in oil. The ease with which an emulsion can be dissolved can be increased if the viscosity of the emulsion is reduced.
Viscosity:
The Viscosity of an emulsion when there is continuous excess phase is virtually the viscosity of said phase. Increasing the proportion of the internal phase increases the viscosity of the emulsion to a point where the emulsion ceases to be liquid. When the volume of the internal phase exceeds that of the external phase, the emulsion particles agglomerate and the apparent viscosity is partially structural viscosity.
Theoretically, the maximum volume, which can be occupied by uniform spherical particles in the dispersed phase of an emulsion is 74% of the total volume. Emulsions having up to 99% of the internal phase can be prepared. In these cases there is considerable deformation compared to the ordinary particle shape of the dispersed phase.
The viscosity of an emulsion can be regulated as follows:
- To reduce viscosity
- The proportion of the continuous phase is increased,
- The viscosity of the continuous phase is reduced,
In suspensions, surface activity agents are added to increase lubrication.
To increase viscosity:
- Thickeners, such as soap gels, gums and alumina gel are added to the continuous phase,
- The proportion of the internal phase is increased,
- The particle size of the emulsion is reduced or the agglomeration of existing particles is reduced,
- Air is incorporated in a state of fine division as the third phase.
The regulation of the viscosity of emulsions has application to the preparation of cosmetic lotions. The object is to prepare a lotion that seems to be thick; that is, that it has high apparent viscosity, but that it remains liquid by remaining at rest for a long time.
A more important difficulty encountered in these formulations is that in the variable storage conditions the gel structure varies and often sets the product and becomes semi-solid so that it cannot flow.
Stability of an emulsion:
The stability of an emulsion depends on the following factors: the particle size, the density difference of both phases, the viscosity of the continuous phase and the finished emulsion, the particle charges, the nature, the efficiency and quantity of the emulsifier, and storage circumstances, that is, high and low temperatures, agitation and vibration, dilution or evaporation during storage or use.
Since the particles of an emulsion are freely suspended in a liquid, they obey Stokes's Law if they are not charged. For many industrial purposes the definition of stability necessarily includes the non-coalescence of the emulsion particles and non-sedimentation. The incorporation of air into an emulsion can result in a marked reduction in stability.
Size and distribution:
The size and size distribution of the particles of an emulsion are governed by the quantity and effectiveness of the Emulsifier, the order of mixing and the kind of agitation that is done. If the size of the emulsion particles is gradually reduced, the color and appearance of the emulsion vary.
Exceptions are made regarding the appearance and color of emulsions when Dyes and Pigments are added and when both phases have similar refractive index. In the latter case, a transparent emulsion is formed regardless of the particle size.
Decrease particle size:
The particle size can be reduced by the following means:
- Increasing the amount of emulsifier
- Improving the hydrophilic-lipophilic balance of the emulsifier
- Preparing the emulsion by reversing phases to obtain an "extended internal phase"
- Through better agitation
The electrical conductivity of an emulsion depends on the conductivity of the continuous phase.
The ease of formation is modified to a greater extent by the efficiency and quantity of the emulsifier and by the inherent properties of both phases.
Emulsions Analysis:
The analysis of emulsions has a lot to do with their properties, as a rule physical and chemical analytical methods are used. Although the order of importance is variable, depending on the emulsion being analyzed, it is usually applicable to the following order:
Type of emulsion It is very important to find out in the first place if the emulsion is oleo-aqueous or hydrooleous, which is achieved in various ways.
Methods to determine the type of emulsion:
- The simplest method is to find out the electrical conductivity. The equipment for this can be easily done by connecting a 10,000 ohm and 0.5 watt resistor in series, electrical contacts for the sample to be tested, a neon lamp without a resistor (0.25 watts, 105 to 120v., General Electric type NE-57) and a push button switch. The sample is placed between the test contacts and the circuit is closed; If the neon lamp gives light, the emulsion is oleo-aqueous, otherwise it is hydrooleous.
- Another method to determine the type of emulsion is to find out its dispersibility in water or oil. The oleo-aqueous emulsions are dispersed in water and the hydrooleous are dispersed in oil.
- A water-soluble dye is dispersed in an oleo-aqueous emulsion and an oil-soluble dye is dispersed in a hydro-oily emulsion. The dye can be used in liquid or solid form.
Emulsion PH:
The pH of an emulsion is of considerable importance. Soap-based emulsions usually have a pH of 8 or more. It is easy to determine the pH with an ordinary glass electrode with pH Paper. These can give an erroneous result if the emulsion contains any product with a tendency to bleach.
The water content of an emulsion follows the pH in importance for the problem of reproduction. One of the best methods to determine such content is the Karl Fischer assessment. If the emulsion is alkaline, some correction can usually be made.
The use to which the emulsion is intended as a rule gives an indication of the components of the oil phase. In some cases, identification analysis, solvent distillation and similar tests are required.
In reality, the result of attempts to undo the emulsion usually indicates the type of emulsifier. Cationic emulsifiers can be considered to be of two types: those that are unstable in alkalis and those that are stable. The second group is not comparable with the stable anionic acid type. However, although the addition of alkali destroys a cationic emulsifier, often enough soap is formed in situ to preserve the emulsion.
The presence of cationic agents can be checked by the addition of anionic agents. Non-ionic agents are divided into two classes: those that are saponified by hot alkalis and those that are stable with this treatment. As a rule, heat facilitates the separation of the phases, and is necessary when the emulsion contains waxes.
Separation can also be carried out by centrifugation, heating, freezing, dilution, the addition of salts or solvents, and with respect to a non-volatile oil phase, by means of incorporating the aqueous phase.
These analyzes indicate the type of emulsion, the class of the emulsifier and the nature and approximate amount of the oil phase, usually providing enough reports to attempt duplication with chosen emulsifiers.
Properties of Emulsifiers:
The term "emulsifier" is often used incorrectly. Emulsifiers form a group of the general class of surface activity agents. Other groups are wetting agents, solubilizers, detergents, suspending agents.
Emulsifiers are used in the formulation of emulsions to facilitate emulsification and give stability to the emulsion. These effects are produced by the reproduction of interphase tension between the two phases and by protective colloidal action, respectively. Ordinarily, emulsifiers are very complex substances and it seems that the more complex the more efficient they work. This is taken into account in formulation practice and combinations of two or more emulsifiers are often used.
Emulsifiers can be divided into ionic and non-ionic. The ionic emulsifier consists of an organic lipophilic group and a hydrophilic group. Ionic emulsifiers are subdivided into anionic and cationic, depending on the nature of the active group. Ordinarily, the lipophilic portion of the molecule is considered to be the surface activity portion.
As it is supposed, the anionic and cationic agents of surface activity are not mutually compatible, because by virtue of the ionic charges they tend to neutralize each other and their surface activity is nullified.
Non-ionic emulsifiers are fully covalent and have no tendency to ionization. Accordingly, it can be associated with other surface-active non-ionic agents and with anionic or cationic agents.
Non-ionic emulsifiers are more immune against the action of electrolytes than anionic agents of surface activity. Of the various properties of emulsifiers, one of the most important is the hydrophilic-lipophilic balance. This is an expression of relative simultaneous attraction of an emulsifier with respect to water and oil.
The hydrophilic-lipophilic balance of an emulsifier determines the type of emulsion that tends to be formed.
The solubility of an emulsifier is of the utmost importance in the preparation of emulsifiable concentrates. The emulsifier must remain dissolved under any storage conditions. It is often possible to increase the solubility of an emulsifier with some coemulsive. Various solvents are also common as conjugates or cosolvents.
Interfasal tension is the force that is required to break the surface between non-miscible liquids; It is of interest in emulsification because the lower the interphase tension between the two phases of an emulsion, the easier the emulsification. The extension coefficient (C.E.) is calculated with the surface tension (T.S.) and the interphase tension (T.I.) (for a given oil) according to the following formula:
CE = TS oil - (TS soln. - TS oil / soln.)
The higher the extension coefficient (the more positive), the greater the moisturizing and diffusive power.
The pH of an emulsion is of considerable importance. Soap-based emulsions usually have a pH of 8 or more. It is easy to determine the pH with an ordinary glass electrode with pH Paper. These can give an erroneous result if the emulsion contains any product with a tendency to bleach.
The water content of an emulsion follows the pH in importance for the problem of reproduction. One of the best methods to determine such content is the Karl Fischer assessment. If the emulsion is alkaline, some correction can usually be made.
The use to which the emulsion is intended as a rule gives an indication of the components of the oil phase. In some cases, identification analysis, solvent distillation and similar tests are required.
In reality, the result of attempts to undo the emulsion usually indicates the type of emulsifier. Cationic emulsifiers can be considered to be of two types: those that are unstable in alkalis and those that are stable. The second group is not comparable with the stable anionic acid type. However, although the addition of alkali destroys a cationic emulsifier, often enough soap is formed in situ to preserve the emulsion.
The presence of cationic agents can be checked by the addition of anionic agents. Non-ionic agents are divided into two classes: those that are saponified by hot alkalis and those that are stable with this treatment. As a rule, heat facilitates the separation of the phases, and is necessary when the emulsion contains waxes.
Separation can also be carried out by centrifugation, heating, freezing, dilution, the addition of salts or solvents, and with respect to a non-volatile oil phase, by means of incorporating the aqueous phase.
These analyzes indicate the type of emulsion, the class of the emulsifier and the nature and approximate amount of the oil phase, usually providing enough reports to attempt duplication with chosen emulsifiers.
Properties of Emulsifiers:
The term "emulsifier" is often used incorrectly. Emulsifiers form a group of the general class of surface activity agents. Other groups are wetting agents, solubilizers, detergents, suspending agents.
Emulsifiers are used in the formulation of emulsions to facilitate emulsification and give stability to the emulsion. These effects are produced by the reproduction of interphase tension between the two phases and by protective colloidal action, respectively. Ordinarily, emulsifiers are very complex substances and it seems that the more complex the more efficient they work. This is taken into account in formulation practice and combinations of two or more emulsifiers are often used.
Emulsifiers can be divided into ionic and non-ionic. The ionic emulsifier consists of an organic lipophilic group and a hydrophilic group. Ionic emulsifiers are subdivided into anionic and cationic, depending on the nature of the active group. Ordinarily, the lipophilic portion of the molecule is considered to be the surface activity portion.
As it is supposed, the anionic and cationic agents of surface activity are not mutually compatible, because by virtue of the ionic charges they tend to neutralize each other and their surface activity is nullified.
Non-ionic emulsifiers are fully covalent and have no tendency to ionization. Accordingly, it can be associated with other surface-active non-ionic agents and with anionic or cationic agents.
Non-ionic emulsifiers are more immune against the action of electrolytes than anionic agents of surface activity. Of the various properties of emulsifiers, one of the most important is the hydrophilic-lipophilic balance. This is an expression of relative simultaneous attraction of an emulsifier with respect to water and oil.
The hydrophilic-lipophilic balance of an emulsifier determines the type of emulsion that tends to be formed.
The solubility of an emulsifier is of the utmost importance in the preparation of emulsifiable concentrates. The emulsifier must remain dissolved under any storage conditions. It is often possible to increase the solubility of an emulsifier with some coemulsive. Various solvents are also common as conjugates or cosolvents.
Interfasal tension is the force that is required to break the surface between non-miscible liquids; It is of interest in emulsification because the lower the interphase tension between the two phases of an emulsion, the easier the emulsification. The extension coefficient (C.E.) is calculated with the surface tension (T.S.) and the interphase tension (T.I.) (for a given oil) according to the following formula:
CE = TS oil - (TS soln. - TS oil / soln.)
The higher the extension coefficient (the more positive), the greater the moisturizing and diffusive power.
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