화학공학소재연구정보센터
Industrial & Engineering Chemistry Research, Vol.50, No.4, 2380-2387, 2011
Making Use of the Formulation-Composition Map To Prepare Highly Concentrated Emulsions with Particular Rheological Properties
The effects of the formulation and dispersed-phase weight fraction on rheological properties of highly concentrated water-in-oil emulsions are reported. Because the surfactant concentratiOn is kept constant, emulsion characteristics may be represented on a formulation composition bidimensional map. The formulation variable is the hydrophilic lipophilic balance (BIB) number of the nonionic surfactant or surfactant mixture which ranges from 4.3 to 10. Highly concentrated water-in-dodecane emulsions are prepared using a semibatch process, with a dispersed-phase weight fraction ranging from 0.90 to 0.98. Two major effects are observed in relation to the formulation influence: First, elastic modulus (G') remarkably decreases in the vicinity of optimum formulation whenever the affinity of the surfactant for the oil and water phases is exactly balanced (HLB = 10.5). Second, the elastic modulus value passes through a maximum, concomitant to a minimum drop size, at some distance of the so-called optimum formulation (HLB = 7.7). Hence, the use of a bidimensional formulation composition map allows one to control and to modulate the final rheological properties of highly concentrated emulsions.