How to Make a Non-Newtonian Fluid
Make a Non-Newtonian Fluid Using Cornstarch & Water!
Here we demonstrate how to make a non-Newtonian fluid using everyday cornstarch and water. We also explain the science behind non-Newtonian fluids and propose some experiments for you to try at home!
What You Need To Make A Non-Newtonian Fluid
- One box of cornstarch (at least 16 oz)
- Cold water
- Spoon or egg beater
- Medium size bowl
How to Make It
- Pour about ½ a cup of regular cornstarch into a mixing bowl and gradually add about a 1 cup of water. Stir thoroughly until all the lumps are out and the cornstarch has dissolved completely into the water. It should have the consistency of milk at this point.
- Continue to slowly add more cornstarch while stirring until the mixture begins to thicken and eventually becomes very difficult to stir. Just about the point where the mixture resembles pancake batter, keep adding more cornstarch slowly while stirring.
- As you continue to add cornstarch, with your hands or a spoon, quickly apply pressure to the liquid either by squeezing it or striking it. You should feel the liquid harden as you apply pressure, then gradually soften as you release the pressure. This means that the fluid is almost complete.
- When applying quick pressure, if you feel resistance, you have reached the final mixture! The following video shows this effect:
A Number of Experiments Can be Performed with the Fluid. Try Each of These Out and See What Happens!
- Cool the Non-Newtonian fluid in the freezer.
- Microwave some of the Non-Newtonian fluid.
- Let the Non-Newtonian fluid sit at room temperature.
- Add more water to the fluid.
For each of these experiments, share your results and hypothesis for what may be going on below!
What are some useful applications of the Non-Newtonian fluid?
The Science Behind Non-Newtonian Fluids
Let’s first define viscosity:
Viscosity is the measurable thickness of a fluid, also its ability to resist a change in its physical shape when pressure or a force is applied. As an example, molasses has a very high viscosity and thus flows very slowly with the force of gravity when for example, it is poured out of a jar. Many fluids’ viscosity changes when the temperature of the fluid changes (ex. the thickness of chocolate syrup when it is hot vs. when it cools after being poured over an ice cream sunday). The higher the viscosity of the liquid, the more it resembles a solid object. A great example of this is something called the Pitch drop experiment which you can read about Here: Pitch Drop Experiment-Wikipedia.
This experiment at the University of Queensland, was started in 1927. Professor Thomas Parnell set the experiment up to demonstrate how some apparently solid objects are actually highly viscous fluids. In the experiment a sample of pitch (which actually feels much like glass) was placed in a funnel and allowed to sit for a number of years, with the idea it would actually begin to flow from the funnel with time. It actually did! The pitch flowed so slowly that only 9 drops have been recorded since 1930! This experiment demonstrated that some objects, although may appear solid actually behave much like fluids with very high viscosity.
So what is a non-Newtonian fluid and how does it work?
A Non-Newtonian fluid is a fluid that behaves differently and has different properties than a Newtonian fluid. In particular, non-Newtonian fluids actually thicken their viscosity when pressure or stress is applied to them. So what is actually going on in the fluid when pressure is applied? In essence the particles of corn starch within the water are packed together very tightly. When pressure is applied to them quickly, this forces the particles to pack together even more tightly, much like a solid. When particles become packed together tightly they essentially behave more like a solid than a fluid. So when quick pressure is applied to the non-Newtonian fluid it rapidly transforms to have properties that resemble a solid, which is why striking it with the egg beater in our demonstration resulted in the egg beater actually bouncing off the fluid!
Be sure to try it out, along with the experiments above and let us know what happened and why!