ABSTRACT
I. INTRODUCTION All liquid detergents contain at least one surfactant in the presence of other materials, such as electrolytes, oily materials, and other impurities. Unlike the academic researcher, the formulator must work with industrial-grade raw materials containing significant amounts of different molecules, the properties of which may significantly differ from those of the main material. The understanding of how a given property of a “pure” system is affected by “impurities” is accordingly of essential practical importance. Understanding the principles by which a given product behaves (as is or under use conditions) allows us to replace counterproductive trial-and-error by more efficient methods with a broader range of potential applications. Phase diagrams are very useful tools to achieve this understanding.
II. WHAT IS A PHASE DIAGRAM? A phase diagram is a graphic representation of the phase behavior of a system under study. The behavior of a single component as a function of temperature and pressure can be represented on a phase diagram, which will show the conditions under which a material is a solid, liquid, or gas. More complex phase diagrams may involve several components. Phase diagrams are very useful tools for formulation, as they allow one to define not only the acceptable composition range of a product but also enable one to optimize the order of addition of the different raw materials.
