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Simple Techniques to Make Non-Newtonian Fluids By Yourself

Anamika Kumari Jun 10, 2019
The idea of teaching rheological properties in continuum mechanics might seem boring and tiresome to most teachers. Here we present an activity, to make oobleck, a non-Newtonian fluid with cornstarch and water, to help scholars develop a better understanding of the same.

Fun Fact

Interestingly, with the right amount of a shear thickening fluid and the right speed, it is actually possible to walk over this fluid without drowning in it.
Non-Newtonian fluids are the fluids whose viscosity depends upon shear stress and shear stress rate. They exhibit rheological properties―properties of both solid and fluid―depending on the amount of stress being applied as well as the time duration for which it was applied.
Generally, visualizing this concept can be tricky. With a few simple ingredients, it is possible to make non-Newtonian fluids anywhere, be it home, school, or college. Added a refreshing fun element to this process will enable the students to also 'feel' the actual scale of stress that is required to bring upon variations in the non-Newtonian fluids.

What You'll Need

➻ A pair of disposable gloves
➻ 2 cups of cornstarch
➻ A bottle of liquid starch
➻ Color additive
➻ 1 lab dropper
➻ A large bowl
➻ 1 cup of water
➻ An airtight jar or a Ziploc bag
➻ One medium-sized aluminum mold
➻ A bottle of glue
➻ A sheet of kitchen paper

Making 'Oobleck'

❖ Put on the gloves neatly to cover your palms and wrist.
❖ Take the large bowl and put the cornstarch in it.
❖ Gradually, pour water in the bowl to make a smooth and silky cornstarch paste.
❖ Stir more cornstarch or water to the bowl, in order to make the mixture thicker or thinner.
❖ Stir with your hands until you can feel the pressure from the fluid on your hands. This pressure shall decrease with speed, and increase with an increase in speed.
❖ Add some food color to the Oobleck to give it a 'jello' or 'slimey' appearance for fun.

Time for Some Fun

✤ Stir the mixture slowly with a finger and experience how smoothly it swirls. Gradually increase your speed of stirring. The mixture now tries to restrict your movement inside it.
✤ Take some mixture in the aluminum mold, and roll it into a ball with continuous rotation and application of a light force with your palm. Then, release that ball of the mixture and watch it spread according to the shape of the mold.
✤ Dip your finger very slowly in the mixture that has spread, and observe how it gets dipped easily. Now, try to slap its surface with a swift motion of your palm. Observe that the 'oobleck' offers resistance to this move. Also, the fluid does not splash as expected. Instead, it forms an even firmer solid surface.
This is the simplest and the most common way of creating a non-Newtonian fluid. In the absence of cornstarch, we have other options like silly putty, ketchup, and jello to demonstrate the properties of non-Newtonian fluids. Let us now see how to make silly putty.

Making 'Silly Putty'

❖ Take a bowl and pour the glue in it.
❖ Add a few drops of color additives using a dropper, and mix well until the color is evenly spread.
❖ Pour liquid starch over the colored glue.
❖ Stir up the contents of the bowl and let it sit for at least 5 minutes.
❖ Extract the entire contents of the bowl, and place it on a clean sheet of kitchen paper.
❖ Knead thoroughly for about 10 minutes to remove excess moisture.

Time for Some Fun

✤ Roll a ball out of the silly putty. Hit that ball against a hard surface and watch it bounce.
✤ Hold the ball between the fingers and give it a quick snap. The entire portion 'breaks' into two.
✤ Now, take some of your product in your hands and spread your fingers. The silly putty shall 'flow' in between your fingers.
Easy to create and understand, these non-Newtonian fluids require careful disposal. Unused or leftover fluid must be put away in a Ziploc bag or stored in an airtight container. One must never try to flush the leftovers or used oobleck or silly putty down the drain. They have a tendency to clog the drainpipes and create nuisance later.