Foam Behavior of Laundry Detergent in Rinsing Process

Abstract

The relationship between the surface tension change with time and the foam volume was investigated for a system containing anionic AOS, LAS and/or nonionic alkyl or s-alkyl poly (oxyethylene) ether with alkyl chains of the same length. Dynamic and equilibrium surface tension was measured by the vibrating jet and Wilhelmy's plate methods, respectively. The anionics showed similar foam volume and surface tension change with time. In regard to the nonionics, on increase in the number of moles of ethylene oxide per molecule was found to make the equilibrium surface tension higher and foam volume smaller. As for dynamic surface tension change, some difference was noted between the alkyl and s-alkyl poly (oxyethylene) ethers. That is, the dynamic surface tension of the s-alkyl poly (oxyethylene) ethers decreased with an increase in the number of moles of ethylene oxide per molecule (abbrev. “EOp”), but that of the alkyl poly (oxyethylene) ethers remained constant regardless of EOp. In AOS/nonionics mixed systems, a s-alkyl poly (oxyethylene) ethers having a high EOp gave lower dynamic surface tension and smaller foam volume.