SpectraCode Inc.West Lafayette, Ind.

Dec. 21, 2004
RP-1 Polymer Identification System

Speed, accuracy, and broad spectrum application are the benefits of a new technology that identifies plastics so they can be sorted for recycling. Unlike current devices based on infrared spectroscopy and visible light, the RP-1 Polymer Identification System from SpectraCode Inc., West Lafayette, Ind., relies on Raman laser spectroscopy, a highly discriminating technology that also works on dark and black plastics. Originally developed by a group of researchers at Purdue University, the current unit utilizes a handheld probe about the size of a hair dryer, connected by an umbilical cord to a mobile unit. Analysis is done by pointing the probe at the sample and irradiating it with the laser. When the laser strikes the sample, the plastic's molecules vibrate, causing the laser to scatter in a pattern that is specific for each plastic. The scatter pattern is sensed, and identification is made in about a tenth of a second. "It's faster than a grocery-store bar-code scanner now," says Ed Grant, co-inventor and SpectraCode CEO, "except there is no bar code." Dark and black plastics currently require about four seconds for identification, with the unit operating at reduced power to minimize fluorescence of ingredients in these plastics. "The SpectraCode instrument is a very significant advance when it comes to the type of technology that will work on the shop floor, and give the kind of accuracy, precision, and reliability in plastics identification for recycling," says Michael Fisher, director of technology, American Plastics Council, Washington, D.C. 1998 marks the first year of full production use of the unit at American Commodities Inc.'s Flint, Mich., facility, where plastic materials from wrecked and dismantled vehicles are separated and recycled back to Visteon Automotive Systems, an enterprise of Ford Motor Co. Visteon now supplies Ford with 40% of its molded plastic parts as a vendor. For Ford, which has an initiative to add 25% recycled material to all plastic moldings, American Commodities is recycling thermoplastic olefin and polycarbonate/pbt alloy, primarily in the form of bumpers, in million-pound quantities annually. The device is also used there to identify nylon, ABS, acrylic, and polycarbonate in rocker panels and side claddings. "Previous technologies for identifying dismantled materials were too slow and relied too much on operator accuracy," says Bill Orr, manager of Ford's worldwide vehicle recycling planning. "We expect this technology to provide higher-quality resin at acceptable prices." The Vehicle Recycling Partnership, a research project of the Big Three automakers, also is looking at the SpectraCode device for separation of shredder residue, eventually in a continuous operation. Currently 75% of a car, the metal, goes through some form of recycling. Shredded residue represents virtually everything else: plastics, upholstery, tires, etc. "In the past we have been limited to identification of light or medium-dark colors," says Claudia Duranceau, engineering project manager for the partnership. "And any idea of filler content has been very 'iffy.' But with the Raman laser we are able to identify if there is mica, or talc, or glass (reinforcement/filler in the plastic). It looks like we will also be able to quantify amounts as well, which we have not been able to do with other techniques. All this plus black, which is very unusual. The SpectraCode device is also fast enough to introduce automation." To avoid shipping mismolded parts, Delphi Automotive Systems Inc. is testing the device in a qualification of parts out of the mold to confirm they conform with material specification. "You shoot the parts right through the plastic packaging, and (based on the composition), it gives you the part number of what it's looking at." Beyond the automotive industry, Grant sees applications in sorting synthetic fibers in carpets, plastics used in construction, film products, and other packaging materials. Because of its discriminating molecular identification ability, the instrument could also find a home in rapid scanning and process monitoring in drug and food operations.

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