“Potato plastic” experiment
How to make plastic from a potato
Potatoes are very rich in starch–a polymer of vegetable origin, which we use very often in everyday life. Today we’ll show you how to make a neat toy from starch!
Observe safety rules when working with flame and heated objects. Don’t taste the toy.
Warning! Only under adults supervision.
Reagents and equipment:
- gauze (or medical bandage);
- heating device;
- any food coloring (not obligatory);
- glass container;
- citric acid (or any other acid, for example vinegar);
- baking mold of your choice.
Grate the potato finely, and add a small amount of water (200 ml) to the potato, to rinse as much starch away as possible, and stir. Then put the mixture through a funnel with gauze, to separate the juice from the starch.
After a few minutes, when the starch has settled, drain the juice. To the sediment add 30 ml of water and stir, and pour the solution into a clean beaker. Add a few drops of food coloring and 30 ml of a 5% citric acid solution, and 15 ml of glycerol.
Then, constantly stirring, heat the solution, without letting it boil. Over time the solution will thicken considerably, and then become liquid again. Pour it into the ice cube mold and leave it at room temperature for 3 hours.
Acid causes the branched structure of starch to break down. It turns into long chains and becomes elastic. When the solution cools, these chains become densely stacked together, turning into a dense mass. The evaporation of water also assists the formation of dense material.
When glycerol is added the toy does not crack, as the glycerol molecules fit between the starch molecules, maintaining its elastic state – the toy does not crumble like shortbread.