The mixing effect of surfactants an foam formation was studied from the stand point of foam ability, foam stability, surface tension, and surface viscosity. The system investigated was Na, Na-dimethyl-Nε-lauroyllysine (DMLL) -sodium α-olefin sulfonate (AOS). Foam abihty and stability in the DMLL single systems increased with concentration, and became constant above the he critical micelle concentration (cmc). The foam stability of DMLL was greatest near its isoelectric point. The foam ability and stability of AOS solutions were maximum at cmc.
In DMLL-AOS mixed systems, when the total concentration was constant below cmc, the foam abilities of mixed solutions at any mixed ratio exceeded those of both single systems and the surface tension of a mixed solution was less than those of single solution.
The foam stability of AOS solutions increased somewhat on adding DMLL. The surface viscosity of DMLL/AOS mixed solutions increased with the concentration below cmc.
In DMLL-AOS mixed systems, surfactants were found to exert a mixing effect on foam formation.