Abstract
Examinations were made on the effect of Tween group emulsifiers, with combination of Span-20 and Tween-81 among them, to discuss the required HLB in detail, for o/w type emulsions with the use of various measurement methods. Oil-in-water emulsions were prepared containing 45% of dispersed phase. The emulsifiers used were commerical grade nonionic surfactants of four Tweens and Span-20, and the oil used was a mineral oil. Emulsion was formed by agitation, and emulsion stability was measured with four apparatuses, measuring cylinder, Coulter counter, turbidimeter, and rheometer. Following results were obtained, 1) The rate of separation was affected largely by the kind of emulsifiers, which increased in the order of Tween-81, Tween-81+Span-20, Tween-85, Tween-20, and Tween-21. 2) The o/w emulsion showed the maximum value of droplet number at characteristic HLB value equal to 10.0. 3) Viscosity of the emulsion increased with the increase of emulsifier concentration.
