Effects of Tween and Span Group Emulsifiers on the Stability of o/w Emulsions

Abstract

The effect of blending Tween and Span emulsifiers on emulsion formation were investigated and the HLB values required to produce stable o/w emulsions are considered in detail. The emulsifiers used were the commercial grade Tween series and Span series, and the oil used was a liquid paraffin (dispersed phase). Emulsion stability was measured by four methods: with a measuring cylinder, a Coulter counter, a turbidimeter, and a rheometer. The following results were obtained; (1) The rate of separation increased in the following order with blended emulsifiers: Tween 80 + Span 20, Tween 20 +Span 20, Tween 40 +Span 20, and Tween 20 +Span 80. However, the emulsion prepared with Tween 20 +Span 80 was unstable over the whole range of HLB. (2) The o/w emulsions prepared using mixtures of Tween and Span showed a maximum droplet number at an HLB value of 11.0. (3) The viscosity of the emulsion prepared with Tween alone was clearly smaller than those obtained with blended emulsifiers. © 1979, IEEE. All rights reserved.