This paper examines the interactions of linear alkylbenzene sulfonate (LAS) surfactants with calcium ions. Calcium sulfonate precipitation boundary diagrams are given which provide a convenient way to study these interactions over a wide range of surfactant and hardness ion levels. Some implications of these interactions for detergency performance are discussed.

Optimizing the removal of solid sebum soil appears to depend on both the surfactant and the soil substrate. Like other solid, organic soils, sebum's removal from hard surfaces involves penetration of the surfactant (and associated solvent molecules) into the soil. This soil‐softening (liquefaction) process prepares the soil for secondary processes (roll‐up, abrasion, emulsification, etc.) which accomplish soil removal. A smaller hydrophobe and lower HLB both appear to aid soil removal by increasing surfactant penetration into the soil. However, when solid sebum is present on cloth, the ability to wet the cloth matrix becomes important. Surfactants better able to promote cloth wetting appear to be better at penetrating the soil, because wetting increases the amount of surfactant in contact with the soil.

Like other commercial surfactants, commercial linear alkylbenzenesulfonate is not a single compound but a mixture of components. This mixture comprises different carbonchain homologs, different phenyl isomers, and, in addition, the manufacturing co-product, dialkyltetralin sulfonate. Current manufacturing technology makes it possible to easily vary the average carbon chainlength. On the other hand, the phenyl isomer distribution and dialkyltetralin sulfonate content can be changed only within a certain range. Each of these variations in composition affects performance. This study reports on the effect of commercial alkylbenzenesulfonate composition on surface tension, solubility, viscosity, foam stability, and detergency. The study shows that average carbon chainlength affects all performance properties. Phenyl isomer distribution and dialkyltetralin sulfonate content affect only solubility and viscosity. JAOCS 74, 837-845 (1997). FIG. 17. Effect of phenyl isomer distribution and dialkyltetralin sulfonate content on foam stability of C 11 average NaLAS. T = 45°C, use level = 400 ppm surfactant, water hardness =150 ppm.

The salt thickening properties of solutions of sodium dodecyl ether sulfate derived from alcohol ethoxylates with either peaked or conventional ethylene oxide distribution are reported. Sodium dodecyl ether sulfates with a peaked ethylene oxide distribution salt thicken more than those with a conventional ethylene oxide distribution. Rheological and light scattering studies are consistent with a model in which viscosity arises from the interaction of rod-like micelles.

This paper compares the appearance and detergency properties of LAS solutions in which Ca(LAS)2 has formed either in the presence or absence of a micelle promotion agent.