Mullaniiskuse

Mullaniiskuse is the moisture content of a foam or froth, referring to the amount of liquid retained within the liquid films and the network of liquid channels that separate gas pockets. The term derives from Estonian mull (foam, bubble) and niiskus (moisture). In colloidal and foamy systems, mullaniiskuse is an important parameter because it governs stability, drainage dynamics, and coarsening of the foam. A higher liquid fraction generally slows film thinning and drainage, leading to longer-lived foams, while a lower fraction can accelerate coalescence and collapse.

Measurement and assessment of mullaniiskuse typically involve determining the liquid fraction of a foam, either by gravimetric methods (weighing samples before and after drying) or by spectroscopic techniques that quantify water content. Advanced methods include magnetic resonance imaging or tomography to map liquid distribution in three-dimensional foams and to estimate mullaniiskuse in different regions of the structure.

Factors affecting mullaniiskuse include the type and concentration of surfactants, the viscosity of the continuous phase, temperature, presence of solid particles, and external stresses such as shear or compression. Environmental conditions and formulation additives also influence drainage rate and film stability, thereby altering the moisture retained in the foam.

Applications of understanding mullaniiskuse span several industries. In food and beverages, it relates to whipped creams, mousses, and beer foams, affecting texture and stability. In cosmetics, personal care foams rely on appropriate mullaniiskus for volume and feel. In materials science and firefighting foams, controlling liquid content is essential for performance and safety.