Polystyrene is a very versatile plastic that can be rigid or foamed. General-purpose polystyrene is clear, hard, and brittle. It has a relatively low melting point. Along with polyethylene, polystyrene dominates the plastics commodity market. Its low price and fair structural properties make it ideal for short-term use and disposable applications (Plastics Technology Center). In summary, PS has the following physical properties:
- Low impact resistance
- Fair strength and stiffness
- Poor chemical resistance
- Moderate heat resistance
- Low price
- Easy processing
Typical End Uses
Typical applications include protective packaging, containers, lids, cups, bottles, trays and tumblers ("Plastic Packaging Opportunities and Challenges," American Plastics Council, 1992).
For more technical information on PS, see the EPS Industry Alliance website.
In 1996, 6.1 billion pounds of virgin PS resin were produced in the U.S. In March 1996, Franklin & Associates estimated for EPA the amount of PS in products discarded in the municipal waste stream at 2.53 million tons for 1994. Franklin also estimated that 0.03 million tons of PS were recycled in the U.S. in 1994.
General estimates of California PS rigid (nonfoam) packaging generation, taken from the Society of Plastics Industries (SPI) and factored to California (using a factor of 10 percent of U.S. total), indicate that about 31,400 tons of PS packaging containers were generated in California in 1996. PS recovery estimates specific to California are not available.
Estimates are not available for the amount of PS postconsumer resin (PCR) used as manufacturing feedstock in California. In general, recycled PS could be used in the manufacture the following commodities:
- Disposable tumblers and utensils
- Toys (impact modified)
- Appliance components (low end)
- Packaging, snap boxes, jars
- Insulation (foamed)
- Tape cartridges
- General commodity items