Laboratory measurement of the thixotropy index
You want to measure the thixotropy index of your materials
What is thixotropy?
Thixotropy is a property of certain materials that become more fluid when subjected to stress, such as movement or agitation, and then return to their initial consistency when at rest. In short, a thixotropic material liquefies when agitated or applied under stress and becomes viscous again once the agitation ceases, as in the case of paint, for example.
This property is sought after in many products such as cosmetics, adhesives, food products and medical devices.
What is the thixotropy index?
Thethixotropy index is a quantitative measure of the thixotropy of a material. It is used to evaluate the difference in viscosity of a product at two distinct points in time: before and after being subjected to shear (or agitation). The higher the thixotropy index, the greater the variation in viscosity as a function of time or shear rate.
The thixotropy index is important for manufacturers because it allows formulations to be adjusted to guarantee correct application while ensuring the stability of the product in its resting state.
How is the thixotropy index measured?
This index is determined by a rheological test, in which the viscosity of a product is measured at a low shear rate (rest) and at a higher shear rate (agitation), then after returning to rest. The difference between these viscosities gives an indication of the extent of the thixotropic effect.
Our FAQ
The thixotropy index is crucial in several industries, such as:
- Cosmetics: in shaving foams, hair gels, toothpastes, face creams, and products containing hyaluronic acid.
- Aeronautics: for epoxy resins used in structural composites.
- Pharmaceuticals: in medical gels and ointments.
Automotive: in adhesives and sealants. - Energy: for drilling fluids and sealing resins.
Hyaluronic acid, commonly used in dermal fillers, moisturisers and eye treatments, requires a suitable consistency to facilitate application while ensuring even distribution. The thixotropic index ensures that the gel becomes fluid during application and regains its viscosity at rest for a prolonged effect.
Thixotropic epoxy resins enable precise and uniform application during composite part manufacturing processes. They facilitate material placement and prevent dripping while ensuring dimensional stability after application, which is essential for the manufacture of critical parts.
- Shaving foam : the foam remains solid in its packaging but liquefies so that it can be easily spread on the skin before becoming firmer again once applied.
- Toothpastes : they require a good balance between fluidity when applied to the brush and solid consistency to remain in place in the tube.
In pharmaceutical products such as gels and ointments, good thixotropy allows for easy application to the skin or mucous membranes while ensuring even distribution of the active ingredients.
