Creepy Silly Putty
Students learn about viscoelastic material behavior, such as strain rate dependence and creep, by using silly putty, an easy-to-make polymer material. They learn how to make silly putty, observe its behavior with different strain rates, and then measure the creep time of different formulations of silly putty. By seeing the viscoelastic behavior of silly putty, students start to gain an understanding of how biological materials function. Students gain experience in data collection, graph interpretation, and comparison of material properties to elucidate material behavior. It is recommended that students perform Part 1 of the activity first (making and playing with silly putty), then receive the content and concept information in the associated lesson, and then complete Part 2 of the activity (experimenting and making measurements with silly putty).
Students use silly putty to explore and understand viscoelastic behavior.
Bioengineers study biological materials and how they function in healthy and diseased states. Since biological materials exhibit viscoelastic behavior, engineers must understand this behavior in order to fully characterize these materials. Engineers may also design devices that come into contact with biological materials. So, to ensure effective and successful device performance, engineers must understand how the biological environment reacts to the forces that a device imposes. Polymers such as silly putty also exhibit viscoelastic behavior and can be used to demonstrate and learn about the functioning of biological materials.
After this activity, students should be able to:
- Demonstrate two viscoelastic material behaviors (strain rate dependence and creep) with silly putty.
- Explain the effects of borax concentration on the material properties of silly putty.
- Graph collected data using Microsoft Excel.
- Explain sources of error in experimental data.