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Activity (Hands-On)Grades 10 - 12

Bridging to Polymers: Thermoset Lab

A photograph shows two tables placed a few inches apart, on which the opposite ends of a long, clear mold of an epoxy and amine mixture rest. A weighted string hangs from the center of the mold, which is bowed a little, showing the flexibility that exists under strain.Thermoset lab setup

Students act as engineers to learn about the strengths of various epoxy-amine mixtures and observe the unique characteristics of different mixtures of epoxies and hardeners. Student groups make and optimize thermosets by combining two chemicals in exacting ratios to fabricate the strongest and/or most flexible thermoset possible.

Engineers design more flexible thermosets by either an excess or lack of sufficient amine in their reactions. By learning how to make and optimize thermosets, students mirror chemical and polymer engineers who design new formulas for the multi-billion dollar plastics industry. When engineers make erasers, the mixture must be one that is very flexible. When engineers create car tires, they must be very strong. Every application requires a different working knowledge of how to formulate thermoset mixtures. Through this activity, students see the key role engineers play in the creation so many items that we rely upon every day.

After this activity, students should be able to:

  • Determine what ratios of amine added to epoxy optimize flexibility and strength of the material and explain that strength has to do with the optimum stoichiometry.
  • Describe how flexibility can be created in thermoplastics by ensuring that a less than optimum stoichiometric reaction takes place.
  • Define a thermoset and thermoplastic.

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