Volume 42, Issue 4

In recent years dynamic surface tension has become increasingly used in industrial laboratories. For a wide range of applications it can be used to improve surfactant selection. Dynamic surface tension is a non-linear function of surface age and concentration. This must be taken into account when comparing surfactants. The concepts of effectiveness (magnitude of effect) and efficiency (concentration required for desired effect) are discussed. Efficiency parameters are more time-consuming to measure, but may give more relevant and reliable information. A ring test with an anionic surfactant using the maximum bubble pressure method showed good agreement between six laboratories. The results indicated that c 20 (concentration for reducing surface tension by 20 mN m −1 ) at 0.1 s lifetime is a robust parameter for surfactant characterisation.

Soiling degree and cleanability of different polyester textile materials before and after impregnation with a soil release polymer (SRP) has been systematically investigated. The use of an imaging instrument for the optical roughness analysis operating on the principle of chromatic aberration allowed visualisation of a transparent SRP film on impregnated textile surfaces. Through visualisation of the SRP film and quantification of its relative area, a possible mechanism of cleanability due to impregnation with SRP is proposed.

The properties of microscopic foam films formed by two commercial surfactants, sodium alkylethoxy sulfate and linear alkylbenzene sulfonic acid as well as by their mixtures are studied. The results obtained refer to the following dependences: surface tension on surfactant concentration at three different electrolyte concentrations; film thickness on electrolyte concentration at constant surfactant concentration; film thickness on surfactant concentration at constant electrolyte concentration; disjoining pressure on film thickness (disjoining pressure isotherms). Calculated are the following physicochemical parameters: the diffuse electric layer potential, surface charge, molecule area for the respective surfactant and close packing surface concentration of the adsorption layer. The data obtained provide an option to link the model foam film experiments with the real processes and systems.

Alkyl glucosides have been studied by electrospray ionization mass spectrometry. The effect of the hydrophobic and the hydrophilic parts of these compounds on the stability of [M + Na] + ions has been evaluated by mass spectra at growing cone voltages. The longer the hydrophobic or the hydrophilic part, the higher the stability of these ions. It has been also found that solvent used affects the abundances of [M + Na] + ions. In order to check if the radii of alkali metal ions influence the stability of their adducts with the compounds studied, the mass spectra have been recorded for solution containing lithium and potassium ions. The cations of smaller radius form more stable adducts, especially with the compounds having longer hydrophobic parts.

The conductance of the solutions of strontium octanoate, hexanoate and pentanoate have been measured in water at 35–50 °C in order to determine the micellar behavior of strontium soaps in water. The result shows that these soaps behave as weak electrolyte in water and the Debye Hückel Onsager equation fails for solution of these soaps.

The influence of protonated species or nonionic forms of N, N-bis(2-hydroxyethyl) dodecylamine oxide (C 12 DHEAO) on interfacial properties is studied by measuring foamability, foam stability, equilibrium surface tension and surface viscosity. Surface tensions of the protonated species with various counterions, Cl − , NO 3 − , ClO 4 − and BF 4 − show a decrease in the following order: C 12 DHEAO Cl − > C 12 DHEAO NO 3 − > C 12 DHEAO ClO 4 − > C 12 DHEAO BF 4 − . Foamability done using shaking method shows a reverse order for Cl − , NO 3 − , ClO 4 − . But the foamability of C 12 DHEAO BF 4 − is lower than that of C 12 DHEAO ClO 4 − . This has been explained in terms of the differences in the lipophilicity the micellar stability. This is further confirmed by our dynamic surface tension results. The equilibrium surface tension values for 20mM C 12 DHEAO solution shows a vague minimum in the range 4.20 < pH < 5.81. The foamability of C 12 DHEAO solution shows decrease with the values of pH. This can be elucidated by the differences in the interactions between cationic and nonionic species, nonionic and nonionic forms. The foam of protonated C 12 DHEAO having counterions Cl − , NO 3 − and ClO 4 − are very unstable. The foam stability of C 12 DHEAO BF 4 − is much greater than other protonated C 12 DHEAO. The foam stability of C 12 DHEAO solution at different values of pH shows similar order as surface tension. Foam are more stable in the range 4.20 < pH < 5.81 than that at other values of pH.

Foam concentrates for fire extinguishing have not been produced in Ukraine up to 1995, and need in them has been satisfied owing to their import. The purpose of the researches was development of biologically “soft” foam concentrates meeting today's requirements for the purpose of organization of their production in Ukraine. Analyses of raw materials sources and technological base of the country have been made as well as research of a number of surfactants, compounding of some foam concentrates have been developed and their production in Ukraine has been organized. Conditions of the most efficient application of a number of foam concentrates and ways for increasing of storage stability of their aqueous solutions in fire extinguishers and fire fighting installations have been found. A few normative documents and recommendations concerning testing and application of foam concentrates for fire extinguishing have been worked out.

Novel sodium sulfated aryl oleic acid alkanolamide surfactants (SSAOAA) with different hydrophobic groups are prepared. An aromatic ring introduced to a long alkyl chain has a significant effect on the effectiveness in reducing water surface tension. The critical micelle concentration (c.m.c.) of one product and the surface tension (γ c.m.c. ) at the c.m.c. are investigated. Surface active properties of sodium sulfated aryl oleic acid alkanolamides are compared to those of conventional sulfated fatty acid alkanolamides. Results show that the c.m.c. decreases with increasing the sizes of alkyl chains.

A new group of nonionic ester surfactants was synthesized. New esters were obtained in high yields from commercially available poly(oxyalkylated) alcohols and fatty acid chlorides under mild reaction conditions. Their structures were confirmed by GPC and HPLC chromatography. The surface properties such as critical micelle concentration (c.m.c.), surface excess concentration, G c.m.c. , and surface area per molecule, A c.m.c. , were determined. The emulsification properties of the new esters were investigated.