Close Encounters of the Polymer Kind
The Weissenberg Effect in action.Copyright 2013 Brian Rohde, NSF GK-12 Program, University of Houston
Polymers are a vital part of our everyday lives and nearly all consumer products have a plastic component of some variation. Students explore the basic characteristics of polymers through the introduction of two polymer categories: thermoplastics and thermosets. During teacher demos, students observe the unique behaviors of thermoplastics. The fundamentals of thermoset polymers are discussed, preparing them to conduct the associated activity in which they create their own thermoset materials and mechanically test them. At the conclusion of this lesson-activity pair, students understand the basics of thermoplastics and thermosets, which may entice their interest in polymer engineering.
Polymer production (thermosets and thermoplastics) is a multibillion dollar industry in which chemists and polymer engineers collaborate to develop products. For successful polymer production, a deep understanding of polymer physics and the unique behavior of polymers is required so that the material properties are fully exploited. Polymer chemists come up with chemical pathways to create polymers. Polymer engineers understand how these new polymers behave so they can maximize mechanical properties for particular applications. And, the process engineers who control large-scale polymer production are aware of how polymers behave differently than their simpler counterparts so that polymer reactions and subsequent production of particular polymer parts can be mass produced. Collectively, these specialists produce products that ultimately improve our everyday lives.
After this lesson, students should be able to:
- Define a polymer and list everyday examples (at least one thermoset and one thermoplastic).
- Describe three unique polymer behaviors.
- In their own words, describe enthalpic and entropic interactions.
- Explain shear thinning and shear thickening, focusing on the overlying idea not on the details, and how shear thinning pertains to polymers.
- Describe, in their own words, thermoplastics and thermosets.
- Explain, using the classical analogy of a bridge, how to make a stiff and flexible thermoset.