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It's not just milk! These substances can also show magical "time viscosity changes"!
In daily life, we are often exposed to various fluids, from beverages to lubricants to find them.But did you know that the viscosity of some fluids changes over time?These fluids are called non-Newtonian fluids, and the most common phenomena are "thixotropy" and "rheology".These properties are not only valued in scientific research, but also play a key role in industrial applications.
Thixotropic fluid
Thixotropic fluid is a non-Newtonian fluid that produces viscosity changes over time, and its viscosity gradually decreases with continuous shear stress.When the shear stress exceeds a certain threshold, the microstructure of the fluid is damaged, resulting in the properties of shear dilution.This fluid will be relatively viscous at rest and will start to flow when disturbed.
Many colloids and suspensions are thixotropic materials, which usually appear stable at rest, but become more and more fluid after disturbance.
For example, ketchup is a typical thixotropic fluid that decreases in viscosity when you shake or squeeze a bottle and easily flows out; but when no force is applied, it returns to a more viscous state.Greek Yoghurt is also an example, a fluid that can become nearly solid when disturbed.
Practical Application
Thixotropic fluids play an important role in many biological and industrial processes.The cytoplasm, synovial fluid, and the matrix in the human body are all thixotropic, and the same is true for semen.In addition, certain types of honey (such as peppermint honey) will also exhibit thixotropy under specific conditions.
In industrial applications, materials with thixotropic properties such as pencils, paints and printing inks are widely used, especially in situations where rapid flow and re-resistance flow are required.
For example, during printing, the thixotropic ink can stabilize the color structure and ensure that the printed color can be reproduced accurately.This characteristic prevents the sagging of the ink on the vertical surface.
Rheological fluid
The opposite of the thixotropic fluid is a rheological fluid.When this type of fluid is subjected to shear force, its viscosity will increase over time, indicating that it becomes more viscous.The microstructure of the rheological fluid gradually increases under continuous shearing, which may be due to shear-induced crystallization.
Rheological fluids are relatively rare, but they show great potential in many potential applications, especially in the areas of buffering and protection.
Practical Application
Examples of rheological fluids include certain gypsum paste, printing inks, and lubricants.In recent years, researchers have also continued to explore the possible uses of rheological materials, especially in the application of vibration absorption, which may provide significant advantages in military, sports equipment and even automotive safety equipment.
Comprehensive Comparison
To sum up, thixotropic and rheological fluids represent two important concepts in fluid dynamics, emphasizing the different phenomena and applications brought about by changes in viscosity over time.Their potential uses and research directions in the real world are undoubtedly topics worth in-depth discussion for the scientific and industrial circles.
The properties of these magical fluids make us rethink the behavior and performance of fluids, whether in daily life or in professional industrial fields.So, have you ever noticed the changes in the properties of the fluids around you and wondered about the principles behind them?
