 Biodegradable Foam Plastic Substitute Made From Milk Protein And Clay Amid ongoing concern about plastic waste accumulating in municipal landfills, and reliance on imported oil to make plastics, scientists are reporting development of a new ultra-light biodegradable foam plastic material made from two unlikely ingredients: The protein in milk and ordinary clay. The new substance could be used in furniture cushions, insulation, packaging, and other products, they report in the ACS' Biomacromolecules, a monthly journal. David Schiraldi and colleagues explain that 80 percent of the protein in cow milk is a substance called casein, which already finds uses in making adhesives and paper coatings. But casein is not very strong, and water can wash it away. To beef up casein, and boost its resistance to water, the scientists blended in a small amount of clay and a reactive molecule called glyceraldehyde, which links casein's protein molecules together. he scientists freeze-dried the resulting mixture, removing the water to produce a spongy aerogel, one of a family of substances so light and airy that they have been termed "solid smoke." To make the gossamer foam stronger, they cured it in an oven, then tested its sturdiness. They concluded that it is strong enough for commercial uses, and biodegradable, with almost a third of the material breaking down within 30 days. |
Biopolymers trumped the other plastics for biodegradability, low toxicity, and use of renewable resources. Nonetheless, the farming and chemical processing needed to produce them can devour energy and dump fertilizers and pesticides into the environment, wrote lead author Michaelangelo Tabone (ENG, A and S '10), who conducted the analysis as an undergraduate student in the lab of Amy Landis, a professor of civil and environmental engineering in Pitt's Swanson School of Engineering.
Tabone and Landis worked with James Cregg, an undergraduate chemistry student in Pitt's School of Arts and Sciences; and Eric Beckman, codirector of Pitt's Mascaro Center for Sustainable Innovation and the George M. Bevier Professor of Chemical and Petroleum Engineering in Pitt's Swanson School. The project was supported by the National Science Foundation.
The researchers examined 12 plastics-seven petroleum-based polymers, four biopolymers, and one hybrid. The team first performed a life-cycle assessment (LCA) on each polymer's preproduction stage to gauge the environmental and health effects of the energy, raw materials, and chemicals used to create one ounce of plastic pellets. They then checked each plastic in its finished form against principles of green design, including biodegradability, energy efficiency, wastefulness, and toxicity.
Biopolymers were among the more prolific polluters on the path to production, the LCA revealed. The team attributed this to agricultural fertilizers and pesticides, extensive land use for farming, and the intense chemical processing needed to convert plants into plastic.
All four biopolymers were the largest contributors to ozone depletion. The two tested forms of sugar-derived polymer-standard polylactic acid (PLA-G) and the type manufactured by Minnesota-based NatureWorks (PLA-NW), the most common sugar-based plastic in the United States-exhibited the maximum contribution to eutrophication, which occurs when overfertilized bodies of water can no longer support life.
One type of the corn-based polyhydroyalkanoate, PHA-G, topped the acidification category. In addition, biopolymers exceeded most of the petroleum-based polymers for ecotoxicity and carcinogen emissions.
Once in use, however, biopolymers bested traditional polymers for ecofriendliness. For example, the sugar-based plastic from NatureWorks jumped from the sixth position under the LCA to become the material most in keeping with the standards of green design. On the other hand, the ubiquitous plastic polypropylene (PP)-widely used in packaging-was the cleanest polymer to produce, but sank to ninth place as a sustainable material.
Interestingly, the researchers found that the petroleum-plant hybrid biopolyethylene terephthalate, or B-PET, combines the ills of agriculture with the structural stubbornness of standard plastic to be harmful to produce (12th) and use (8th).
Landis is continuing the project by subjecting the polymers to a full LCA, which will also examine the materials' environmental impact throughout their use and eventual disposal.
 del.icio.us |
 Digg |
 Reddit |
 YahooMyWeb |
 Google |
 Facebook |
Converting Acid Rain Chemicals Into Useful Products| The content herein, unless otherwise known to be public domain, are Copyright 1995-2010 - SpaceDaily. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement |
