Recycling Carpet: A University Invention Becomes a Green Business

Renewlon®: Recycled Carpet
Renewlon®: Recycled Carpet
Did you know that carpets can be recycled? The typical carpet has nylon fibers and a polypropylene backing. Thanks to Dr. Chris Roberts in the Chemical Engineering Department at Auburn University, there is now a clear, simple, practical way to extract pure nylon powder from used carpet. The remaining polypropylene can be used as well. The technology developed by Dr. Roberts was patented, and the patent estate became the basis for a start-up company, Modular Carpet Recycling (MCR). The elegant process is described in U.S. Patent No. 5,994,417, “Process for recovering polymers from commingled materials,” issued to Christopher B. Roberts and Aron T. Griffith, Nov. 30, 1999.

Formic acid, the compound that provides the sting of ants and stinging nettle, is used to dissolve the nylon. The solution is then injected into a chamber with supercritical carbon dioxide. Formic acid remains soluble in the carbon dioxide but the nylon precipitates out, forming a fine powder. The pressure of the carbon dioxide can then be lowered to take it below the supercritical state which causes the formic acid to separate from the carbon dioxide. Both materials can then be used again. Simple, clean, efficient.

Another group recognized the value of what Dr. Roberts had created and worked with him to commercialize the technology, creating additional intellectual property in the way to bring the technology to an industrial scale.

The polypropylene backing of the carpet, after the nylon has been dissolved away, is also recycled. It can be used to make laminated board materials, for example.

As with most inventions, there is a need for others to contribute further advances to bring the invention forward to the point where it becomes commercial and has impact on society–in other words, to turn the invention into an innovation. Partnerships between industry and universities are increasingly important in solving real world problems in ways that change society (and make real money). And once again, having a patent made the partnership work. Without it, there would have been no motivation to work with the university and less incentive to take on the risk of commercializing an unprotected technology. It’s very basic, but worth repeating: patents can help create partnership opportunities. Patents can make it more likely for research to result in commercially important innovation, not less likely.

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