SHRINKY DINK Experiment

Piece of clear polystyrene plastic. (Obtain from the top of Dannon yogurt container or salad container – will have a recycling code of “6”)

Oven , Permanent Marker and Cookie sheet

Procedure
If using the top of a yogurt container, remove the colored strip from the edge. Otherwise cut out a square piece of plastic. Draw a design on the plastic with a permanent marker.
If desired, punch a hole in the plastic with a hole puncher, so it may be attached to a key chain when finished.
Place on a cookie sheet and put in the oven for about 5 minutes at 350 F (170C)

If you have ever thrown a styrofoam cup into a campfire, you know that styrofoam shrinks considerably when heated. If a 2-litre bottle is filled with boiling water, it will noticeably shrink in size. Many packages are shrink-wrapped in plastic. Certain types of plastics that are put over windows in the winter for insulation must be shrink fitted with a hair dryer. Polystyrene, which is used in this experiment, also shrinks when heated. The reason for this can be traced back to its manufacture.

In order to be made into a film, the polystyrene must be heated, stretched, and then quickly cooled. This locks the plastic into a particular shape and thickness. When heated again, it becomes unlocked and returns to its original position and thickness.