New 'Green' Plastics Start to Sprout

The fastest growing category in polymer compounds probably is “environmentally friendly.” That term can mean almost anything, however. Plastics that contain recycled content probably fit the definition, but often are not of great use to design engineers because of their compromised property values. More interesting are plastics made from renewable resources, such as corn or soy. Increasingly, some of these plastics can be used for injection molding and sometimes even for engineering applications. Another big environmental story line are plastics that meet new guidelines for flame retardancy.

ADDITIVE-FREE FLAME-RETARDANT PLASTIC

Scientists at the University of Massachusetts Amherst are developing a synthetic polymer that is inherently flame retardant. The new polymer wouldn't need the flame-retardant chemicals added to many plastics before they can be used in bus seats, airplanes, textiles and countless household items. Some of these additives have been showing up in dust in homes and offices, fish, fat cells and breast milk, raising concern they pose a risk to human health and the environment. The state of Washington banned a class of flame-retardants from use in household items from mattresses to computers — the first state to do so. The new UMass material uses bishydroxydeoxybenzoin or BHDB as a building block, which releases water vapor when it breaks down in a fire, rather than hazardous gasses. Officials at the Federal Aviation Administration and the U.S. Army are keeping a close eye on the material, but it isn't close to commercialization.

NO-COMPROMISE POLYOLS

DuPont Cerenol is a family of renewably sourced, high-performance polyols (polyetherdiols) that can replace petroleum-based ingredients or finished products without compromising functionality. It offers value-added properties and can increase process efficiencies for a broad range of products in diverse markets including personal care, functional fluids and high-performance elastomers. DuPont says Cerenol can be easily tailored to meet specific needs and performs better in many end uses while providing environmental benefits. Cerenol will be the building block for two other renewably sourced products from DuPont, including Hytrel thermoplastic elastomers made with Cerenol, which will be available late this year.

PLASTIC GROWN IN PLANTS

Mirel is a new natural plastic produced from renewable resources such as corn sugar that will biodegrade in soil, compost, rivers and oceans. It can be used as an alternative to petroleum-based plastic in a wide variety of conversion processes, including injection molding, paper coating, cast film and sheet, blown film and thermoforming. Metabolix, one of its developers, is working with more than 40 prospective customers on more than 60 applications, including consumer products, packaging, single-use disposables and products used in agriculture and erosion control. One of the first commercial applications is a molded stake used to hold sod in place. Natural plastics are produced in specific plant tissues, such as seeds or leaves, directly by photosynthesis using carbon dioxide and water as the raw materials.