In this work, the dominating factors determining if the surface activity of the surfactant solution will increase or conversely decrease when adding certain kinds of nanoparticles have been investigated. Two typical hydrophilic nanoparticles, SiO2 and TiO2 with anionic or cationic surfactants, respectively, have been considered. The surface tension has been measured in a wide range of nanoparticle and surfactant concentrations. It was found that the surface tension of the ionic surfactant solution can be further reduced only if nanoparticles of the same charge were added.
For instance, a system containing 0. Interestingly, the observed synergistic effect is found to be more significant if the surfactant concentration is much lower than its CMC for a given nanoparticle content.
Moreover, the effect is perfectly reversible. The change in contact angle with respect to time is particularly important for investigating the effect of the surfactant. This time-dependency reflects the speed with which surfactants adsorb at the interface with the liquid and act to improve solubility. Foam analyses are relevant in the following sectors for the optimization of foam formation and stability and for preventing foaming:. Surfactants frequently form foam and are often specifically used to produce foam.
Particular areas of application lead to different requirements for foamability, foam stability, moisture content and the size of bubbles in the foam. Our Dynamic Foam Analyzer — DFA foam analysis measuring instrument uses reproducible foam formation techniques and methods for measuring the foam height with respect to time.
The moisture content of the foam and the change in height over a period of time at different heights in a foam column can be measured with our conductivity module. The optical foam structure analysis module determines the bubble size distribution and its time-dependency in order to specifically optimize the nature of the foam. The foaming of surfactants frequently has undesirable effects on processes and product quality. Low-foaming surfactants are often used and foam-inhibiting substances added in order to prevent foaming.
The quickly collapsing foam formed from such mixtures can be reliably analyzed using the DFA in order to optimize foam prevention. Surface rheological investigations increase your depth of knowledge of surfactants in the following areas:. Surface rheology investigates the change in surface tension or interfacial tension as a function of speed, and the degree of change of the interface area. Our surface rheology instruments measure such quantities as the interface elasticity storage modulus and the interface viscosity loss modulus.
These quantities enable conclusions to be drawn relating to the mobility of surfactants and the stability of liquid films as well as droplets in emulsions. The results can also frequently be correlated with foam parameters such as drainage rate and foam bubble stability. An awareness of the interface rheology increases the depth of knowledge of the behavior of surfactants in emulsions and foams. This can then contribute towards the optimization of products and processes in which surfactants play a part.
The interfacial rheological behavior, i.
Foamability and foam stability of three surfactants for body care products were compared using reproducible, automatic Ross-Miles foam analyses according to ASTM D Our application report is an extract from a comprehensive benchmark study carried out to evaluate a new surfactant. Anti-foaming agents are added in order to avoid quality problems due to the formation of foam in printing inks and varnishes.
The efficiency of two silicone-based anti-foaming agents is compared based on time-dependent measurements of the foam height.
Five surfactants are investigated with regard to their effectiveness and efficiency in reducing surface tension by means of static and dynamic measurements. The choice of the most suitable surfactant depends on the process speed. The foaming behavior and foam stability of three low-foaming surfactants are characterized.
teenswinbeseco.cf Data obtained from rheological measurements of the interface show a good correlation with results of the foam height measurement. Foam height measurements and measurements of the modulus of elasticity and modulus of viscosity are carried out on two body-care products.
A commented translation of the paper by C. Several authors [ 4 ] are of opinion that the dynamic friction affects f T Mazo [ 5 ] demonstrated that the dynamic friction may have a greater effect on D T in micellar solutions with scarce swamping or support electrolyte. If the surfactant is ionic, the layer may produce an additional electrostatic barrier against the electroactive ionic species. Two salt concentrations were used: a relatively small concentration 0. Surface properties probed by second-harmonic and sum-frequency generation. Experimental Section Effect of High Salt Concentration on Surfactant Properties Low concentrations of soluble salts are commonly used to tailor surfactants properties such as the critical micellar concentration CMC , the aggregation number in the micelles, and the equilibrium surface tension. It is seen that these values are much larger than values coming from kerosene only.
A relationship can be shown between higher surface elasticity and higher foam stability. A model system is used to show how the cleansing action of mixtures of surfactant solutions and a wetting aid can be estimated. The composition affects the contact angle on a fiber and the interfacial tension with respect to the model contamination. A comprehensive analysis of the possible interactions between surfactants and polymers in solution and the conclusions which can be drawn in relation to rheological measurements.
Measurements on alkyl alcohol ethoxylates show a correlation of the CMC with the size of the ethoxylate head group. The results can be used, for example, to determine the degree of ethoxylation of unknown samples based on the CMC. Certificate courses for successful and reliable measurements. DSA Inkjet. Your search term. Contact Newsletter Seminars Remote. Characterization of surfactants Surfactants as wetting agents, emulsifiers, cleaners or foaming agents assume an important role in the mixing of liquids or when they come into contact with solid substances.
The surface tension is an important parameter for many tasks and processes, e. Measurement of the critical micelle concentration CMC. Measurement of the CMC provides important information for the use of surfactants, e. Measurement of the interfacial tension between liquids.
Measurements of the interfacial tension are often carried out in the following fields and to answer the following questions: Emulsions for foodstuffs, cosmetics or medicines Ageing of hydrophobic liquids, e. Measurement of dynamic surface tension and interfacial tension. Dynamic surface tension or interfacial tension is important, for example, in the following applications of surfactants: Fast industrial wetting processes such as printing, painting, coating, bonding Atomizing capability and wetting when spraying Mixing of liquids for emulsification Checking of surfactant content in cleaning baths Surfaces and interfaces are formed at high speed in various applications and production processes.
Measurement of the contact angle is used to characterize surfactants to answer the following questions: The effect on wetting of adding surfactants Wettability of solids containing surfactants The contact angle is an indication of the degree to which the wetting of a liquid is improved by the addition of a surfactant.
Foam analyses are relevant in the following sectors for the optimization of foam formation and stability and for preventing foaming: Deliberate foam formation: Body care, culinary foams, flotation, firefighting Foam prevention: Printing and coating, cooling lubricants, liquid conveying, industrial cleaning Surfactants frequently form foam and are often specifically used to produce foam.
Surface rheological investigations. Surface rheological investigations increase your depth of knowledge of surfactants in the following areas: Mobility of surfactants Film stability Foam stability Emulsion stability Surface rheology investigates the change in surface tension or interfacial tension as a function of speed, and the degree of change of the interface area. AR : Interfacial rheology of emulsifiers in food The interfacial rheological behavior, i.
This and its companion Volumes 5 and 6 document the proceedings of the 5th International Symposium on Surfactants in Solution held in Bordeaux, France. This volume chronicles the proceedings of the 8th International Symposium on Surfactants in Solution (SIS) held in Gainesville, FL, June ,
AR : Benchmarking the foaming properties of a new, mild surfactant formulation according to ASTM D Foamability and foam stability of three surfactants for body care products were compared using reproducible, automatic Ross-Miles foam analyses according to ASTM D AR : Investigating the foam-inhibiting effect of antifoaming agents in printing lacquers Anti-foaming agents are added in order to avoid quality problems due to the formation of foam in printing inks and varnishes.
AR : Kinetic investigations into the effectiveness of surfactants Five surfactants are investigated with regard to their effectiveness and efficiency in reducing surface tension by means of static and dynamic measurements. AR : Foam behavior and foam stability of aqueous surfactant solutions The foaming behavior and foam stability of three low-foaming surfactants are characterized.
AR : Characterization of liquid foams by the determination of surface rheological properties of surfactant solutions Foam height measurements and measurements of the modulus of elasticity and modulus of viscosity are carried out on two body-care products. AR : Assessing the cleaning ability of queous surfactant solutions on soiled hydrophobic textile fabrics by using contact angle and surface tension measurements A model system is used to show how the cleansing action of mixtures of surfactant solutions and a wetting aid can be estimated.
AR : Critical micelle concentration as a function of head group size for alkyl alcohol ethoxylates Measurements on alkyl alcohol ethoxylates show a correlation of the CMC with the size of the ethoxylate head group.