Thixotropy and rheopecty (also known as anti-thixotropy or rheopexy) are forms of time-dependent rheological behavior that describe how a material’s viscosity evolves under constant shear. Thixotropic materials gradually become less viscous when shear is applied, due to the breakdown of their internal structure, and slowly recover their original consistency once the shear is removed. This behavior is commonly observed in products such as ketchup, yogurt, creams, and paints, where ease of application and structural stability are both important.
In contrast, rheopectic materials exhibit the opposite behavior: their viscosity increases over time under continuous shear, typically due to gradual structure formation or particle alignment. Although less common, rheopecty can be found in specific systems like clay suspensions, heavy greases, and gypsum-based slurries, where controlled thickening during processing or application is beneficial.
Turnaround time: 1 – 10 days
The hysteresis loop is a graphical tool used to analyze thixotropic or rheopectic behavior. It is created by performing a shear rate sweep up and then back down in a rheometer while measuring the corresponding shear stress. For a thixotropic material, the upward curve (increasing shear rate) shows higher viscosity than the downward curve (decreasing shear rate), resulting in a loop where the area between the curves represents the extent of time-dependent structural breakdown.
In a rheopectic material, the situation is reversed: the downward curve (after structure build-up) shows higher viscosity than the upward sweep, forming a reverse hysteresis loop. The larger the area of the loop (in either case), the more pronounced the time-dependent behavior.
These loops not only confirm the presence of thixotropy or rheopecty but also provide quantitative insight into how quickly a material recovers or builds its structure, which is vital for optimizing product performance and processing conditions.
Still have questions? Our team is here to help. Let us know how we can help and we will get back to you shortly!
By filling out this information, you are adhering to our privacy policy.
For returning customers, download the Sample Submission Form and send it back to us.
