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From the Editors of E/The Environmental Magazine
Green-Age Plastics Grow in Fields
They biodegrade and save oil
Dairy products like yogurt always seem to come in packages of low recyclabilty (labeled 5, which our town won’t take). Why aren’t these containers more recyclable? Isn’t there a more eco-friendly container these companies could use?
John Marble, Portland, Maine
The ability to recycle a plastic item rests with many factors, including its material, its usability in new products once it has been broken down into its original components and whether or not a market is in place to facilitate transactions of the recycled materials from sellers to buyers.
Recycling polypropylene (designated 5), the material used in many food containers, is technically possible. The challenge is in separating it from other plastics, including its own many variations, once it arrives at the waste station and beyond. Because of the difficulty and expense of sorting, collecting, cleaning and reprocessing plastics of all kinds, in many places it is only economically viable to recycle a few select types. These usually include polyethylene terephthalate (PETE, designated 1), high-density polyethylene (HDPE, 2) and sometimes polyvinyl chloride (PVC, 3).
Polypropylene is a thermoplastic polymer, meaning that it has density and resins that give it a high melting point, enabling it to tolerate hot liquid without breaking down. It is used in a wide range of food packages where the product goes into the container hot or is later microwaved in the container. It is also used to make bottle caps, computer disks, straws and film packaging. Its toughness, strength, ability to be a barrier to moisture and resistance to grease, oil and chemicals also make it a very attractive material for many uses.
Environmentally friendly alternatives to polypropylene and other plastics are beginning to be developed, however. NatureWorks, a division of Cargill, has developed a corn-based plastic called polylactic acid. While it looks and functions like other plastics, polylactic acid is fully biodegradable, given that it is derived from plant-based materials. Whether it is composted or land-filled, it will biodegrade into its constituent organic parts, though there are debates as to how long that process takes.
Another pioneering company is Massachusetts-based Metabolix, which has partnered with corporate giant Archer Daniels Midland to make corn plastics that the company claims will “biodegrade benignly in a wide range of environments, including marine and wetlands.”
A handful of natural foods companies and retailers, including Newman’s Own Organics, Del Monte Fresh Produce and Wild Oats Markets, are already using corn plastic for some of their packaging, though not yet to replace heat-resistant polypropylene. Analysts expect such plant-based alternatives to come on stronger and stronger in the days ahead as petroleum becomes more expensive and more politically unstable. Even Coca-Cola has started experimenting with replacing its traditional plastic soda bottles with a corn-based alternative. Last October, as part of its green overhaul, Wal-Mart announced it would replace 114 million plastic produce containers a year with biodegradable polylactic acid varieties, sparing about 800,000 barrels of oil annually.
For more infomation:
• NatureWorks: www.natureworksllc.com.
• Metabolix: www.metabolix.com.
• The Society of the Plastics Industry: www.plasticsindustry.org.
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