Paste (rheology)

Paste (rheology) is a term used in rheology to describe a type of deformable material that exhibits properties of both solids and liquids. Pastes are typically thick, viscous substances that do not flow at low levels of stress but can become fluid when a higher stress level is applied.

Characteristics

Pastes are characterized by their high viscosity, which is a measure of a fluid's resistance to flow. They also exhibit yield stress, which is the minimum stress needed to make a material begin to flow. This is in contrast to Newtonian fluids, which flow under any level of stress.

Pastes can be made from a variety of materials, including foods, cosmetics, pharmaceuticals, and construction materials. The specific properties of a paste can vary widely depending on the type and concentration of the particles in the paste, as well as the type of liquid in which the particles are suspended.

Applications

In the medical field, pastes are often used in pharmaceutical formulations. For example, medicinal pastes are used as a delivery system for drugs that are applied topically to the skin or mucous membranes. These pastes are typically designed to adhere to the application site and provide a sustained release of the drug.

In the food industry, pastes are used in a variety of products, from baking to condiments. They provide texture and flavor, and can also act as thickening agents.

See also

• Rheology
• Viscosity
• Yield stress
• Newtonian fluid
• Non-Newtonian fluid