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The Versatile Biofoam Solid
| Article
# : |
20584 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
11 / 1992 |
1,578 Words |
| Author
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Robert L. Morrison
Robert L. Morrison is a senior research scientist at Lawrence
Livermore National Laboratory in Livermore, California. |
Given today's heightened public consciousness of environmental matters, a biodegradable, cost-competitive material that could substitute for some uses of plastics would seem to have a bright future. So it is with SEAgel, a simple, biodegradable foam material made from seaweed through a standard vaccum-drying process.
The SEAgel manufacturing process was made available for commercial development only in March of 1992. yet the commercial interest that it has generated among a wide variety of manufacturers suggests that SEAgel's impact in coming years will be significant. Early applications may be as a replacement for the ubiquitous urethane foam packing peanuts, as thin sheets of insulation in refrigerators, or as pellets containing does of time-release medications.
Origin And Production Methods
SEAgel (Safe Emulsion Agar gel), a rigid microcellular foam, was developed at the Lawrence Livermore National Laboratory (LLNL) in Livermore, California, as part of a classified defense systems research project. However, the material itself and procedures for making it are not classified and have been made available through LLNL's Technology Transfer Department to American science and industry for whatever applications SEAgel may fulfill.
SEAgel is made from agar, a gelatinous material that is derived from the seaweed Rhodophyceae and is used as a nutrient medium for bacterial cultures, as a laxative, and as a food thickener. Rhodophyceae is a red algae with several agar-producing genera, which grow in the Pacific and Indian oceans and the Japan Sea. Chemically, agar is a repeating polymeric sugar.
Making SEAgel begins by emulsifying the agar. First the agar is dissolved in water along with a small amount of a surface-active (detergent-like) agent and an organic nonpolar solvent. This mixture is emulsified in a high-speed blender and then poured into a mold and allowed to gel. However, because of the additives in the emulsion, the newly gelled material retains the microscopic foam structure formed during emulsification.
The gel is then frozen, followed by freeze drying, which leaves behind the foam structure. By varying the conditions during the emulsification process it is possible to precisely control the wall thickness of the foam cells. When the freeze drying is completed the cast SEAgel material is removed from the mold and may be machined
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