All manufacturing processes have environmental consequences, just as all living creatures contribute, however minimally, to environmental degradation. The real answer on environmental impact comes from a comparative analysis with suitable alternative manufacturing processes.

Polystyrene is made from styrene, a petroleum by-product, through a chemical reaction process known as polymerization. In addition to use in food packaging, polymers made from styrene are also extensively used today in the manufacture of automobile parts, electronic components, personal computer housings, boats, recreational vehicles, and synthetic rubber products. More information on styrene is available at the Styrene Information and Research Center (SIRC) website, at www.styrene.org.

Dart Container employs two distinct types of processing to make its products: 1) steam chest molding of expandable polystyrene (EPS); or 2) extrusion of polymer followed by thermoforming to achieve a final product.

Steam Chest Molding

Dart foam cups are made from expandable polystyrene (EPS). The first step in making EPS is impregnating small beads of polystyrene with an expansion agent, usually pentane. The molding process begins with limited expansion of the EPS by contact with steam in a pre-expander. The resulting “prepuff” forms the final product in a mold, also heated by steam that further expands and fuses the prepuff to its final shape and density.

Extrusion/Thermoforming

The three classes of product in this second category are Impact, Oriented Polystyrene (OPS), and Extruded Foam.

Impact - Dinnerware, cold cups, portion containers, and lids are produced from extruded sheets of impact-modified polystyrene, polyethylene terephthalate, or polypropylene that are formed into final products in a thermoforming process utilizing heat and vacuum.

OPS – General Purpose (GP) polystyrene is extruded into a sheet that passes through an orienting device which stretches or “orients” the sheet to achieve strength. This oriented sheet is then thermoformed into a final product. The strength and clarity of OPS products are useful for packaging such items as baked goods, salads, and “deli” products. Our customers value the superior clarity of Dart’s OPS products.

Extruded Foam – Dart also produces foam in a direct injection foam (DIF) process that involves an expansion or blowing agent added to the polymer during extrusion. The resulting foam provides both strength and insulation properties. Most of this product line has the typical pure white of expanded foam, but limited colors are available. Products made from this material include dinnerware and hinged trays.

Polystyrene foam foodservice products are not manufactured with chlorofluorocarbons (CFCs) or any other ozone-depleting chemicals. In fact, Dart has never used CFCs in manufacturing molded foam cups. Those manufacturers of polystyrene foodservice products that employed CFCs in their manufacturing operations ceased using them by 1990 (Judd H. Alexander, In Defense of Garbage [Westport, CT: Praeger Publishers, 1993] 55).

The most common blowing agents today are volatile organic compounds (VOCs) such as pentane. Unlike CFCs, pentane does not affect the upper ozone layer, but does contribute to impurities in the lower level of the atmosphere. State and federal authorities, through laws and regulations, limit the amount of VOC emissions allowed, depending on regional air quality issues. To meet the permitted limits of these regulations, many manufacturers use state-of-the-art technology to reduce pentane emissions (see for example: The Polystyrene Packaging Council, Polystyrene and Its Raw Material Styrene: Manufacture and Use November 1993; Updated January 1996). Whenever possible, Dart uses such technology to capture and destroy VOCs, and, where technically feasible, to capture and reuse pentane.