Tixotrópico

Tixotrópico refers to a property of certain non-Newtonian fluids, such as gels and suspensions, that causes them to become less viscous when subjected to agitation or shear stress, and then to gradually return to their original, more viscous state when left undisturbed. This phenomenon is known as thixotropy.

A fluid exhibiting thixotropy will flow more readily when shaken, stirred, or otherwise mechanically worked. For example, when you shake a bottle of ketchup, its viscosity decreases, making it easier to pour. Once the shaking stops, the ketchup slowly thickens again. This behavior is different from shear thinning, where the viscosity decreases only while the shear stress is applied, and does not recover over time.

The thixotropic behavior is often attributed to the breakdown and reformation of internal structures within the fluid. In many thixotropic fluids, there are interconnected networks of particles or molecules. When the fluid is agitated, these structures are broken down, reducing resistance to flow. When left at rest, the particles or molecules gradually re-associate, rebuilding the network and increasing the viscosity.

Thixotropy is an important characteristic in various applications. It is utilized in paints and coatings, where the paint needs to be easily spreadable during application (low viscosity under shear) but should not drip or sag once applied to a vertical surface (high viscosity at rest). Adhesives, inks, and some food products, like yogurt and honey, also exhibit thixotropic properties that are beneficial for their use.