Metamorphic Magic Plastic

In this “trash-to-treasure” activity, polystyrene clamshell containers (#6 plastic) are used to make hard plastic art pieces.  When polystyrene clamshell containers are produced, the material is heated and stretched into a mold, thus locking the material in an extended state. When this material is heated again, it returns to its unstretched size and shape. This property can be utilized to create a range of crafts, including buttons, key chains, luggage tags and jewelry. If students mass their plastic before and after, this could also be tied to the Law of Conservation of Mass.

physical change
Law of Conservation of Mass

– clean #6 plastic clamshell container (clear plastic)
– scissors
– hole punch
– permanent markers
– oven (e.g. kitchen oven or toaster oven)
– heat-resistant spatula

1. Cut out a shape from the flat portion of the clamshell container. If desired, a hole may be punched (e.g., for hanging or making buttons).
2. Decorate as desired with permanent markers.
3. Place plastic on a baking sheet (decorated side up) and heat at 350°F until shrinking of the material is complete (typically 2-3 minutes).
4. Take baking sheet out of the oven and carefully remove plastic from sheet using a spatula.  Allow to cool for a few minutes.  Careful – plastic is very hot when first removed from the oven!

One source suggests using ZIG Millennium Pens. When the material is first heated, it often curls up before flattening back after additional heating. It generally does not shrink any further after flattening out.  Shapes with acute angles may result in a fairly sharp point in the final product. It is important to have the decorated side up when heating to keep the ink from being in direct contact with the baking sheet.

Safety goggles should be worn at all times.  Care should be taken working with a hot oven.

“Celebrating Chemistry, Rethinking the 3 R’s: It’s Easy to be Green.” American Chemical Society, Accessed July 19, 2012.

“How to Make Clothing Buttons from Shrinking Plastic.” Posted July 18, 2010. Accessed July 19, 2012.