Seeing Polymers in a New Light - Demonstration Kit

By: The Flinn Staff


Discover the bright, rainbow-like color patterns that are created when objects made from polystyrene and other polymers are viewed between crossed polarizing filters. Brightly colored bands of different colors arise due to birefringence, making it possible to “see” areas in the structure of a polymer where the molecules line up in an orderly, crystalline fashion. Crystalline regions may form when a hot polymer is forced through a narrow opening during injection molding or when a polymer is “stressed” by stretching or bending an object. Great applications-oriented demonstration—engineers use this tool to map out stress in plastic models of bridges! All the materials are reusable.

Concepts: Polymers, amorphous versus crystalline structure, polarized light, birefringence.
Time Required: 10 minutes
Materials Provided: Two polarizing filters, polystyrene “jewel” case, polyethylene bags, and craft sticks.