Spectracode Breaks Black Plastics Recycling Barrier

"This technology will be of great interest to the plastics community," says Edward Grant, chief executive officer of SpectraCode and Purdue University professor of chemistry. "Being unable to instantly identify and separate post-consumer black plastics by resin type has presented a significant barrier to their wide-scale recycling."

The problem, says Grant, stems from the inability of a standard spectrometer to quickly detect the component resins of black plastics without overheating or burning the sample.

Black plastics, unlike light-colored plastics, are loaded with carbon. When an intense light source, such as a laser, is used to analyze them, this carbon causes black plastics to absorb light to such a degree that the material can heat up and emit light or even ignite. The signal from this luminescence or burning of the plastic, in turn, obscures its spectroscopic signature, making it difficult for sensors to accurately read the plastic's composition.

The RP-1, SpectraCode's existing point-and-shoot, high-resolution imaging spectrograph, analyzes samples with a monochromatic laser and records their vibrational signatures in the Raman spectrum of the back-scattered light. Raman spectroscopy is able to analyze dark and intensely pigmented plastic materials, but with black plastics, it can only sense the composition of the samples at lower laser powers with relatively long (10 second) measurement times.

Mid-infrared spectrometers, which use absorption from a broadband infrared source, are able to analyze black plastics in some situations. However, in practice, these spectrometers require similar analysis times and suffer other limitations. This inability to instantly identify black plastics led Grant’s team to create the new instrument.

The solution should make recycling more profitable, Grant said.

"Any recycling process must be cost-effective in order for it to take hold in the marketplace," says Michael Fisher, director of technology for the American Plastics Council. "Since there are a variety of grades within different classes of black plastics material, having the technology to discern between the different grades reliably and quickly empowers recyclers to capitalize on the recovery of a greater range of raw materials."

SpectraCode's new technology enables the instant point-and-shoot identification of black plastics, extracting a definitive signature from most black plastics in half a second or less. This speed is achieved through a modified probe that uses a sampling technique SpectraCode calls distributed focusing. This technology, when used in conjunction with the company's RP-1 analysis system, can test black plastic samples at full laser power with no burning.

In November, SpectraCode introduced its distributed focusing technology at the Annual Recycling Conference of the Society of Plastics Engineers. The technology is commercially available and SpectraCode is now accepting orders for delivery in the first quarter of this year.

"There is no question that the plastics industry sees growth in the need for recycled materials in the future," says Fisher. "New technology that supports environmentally sound and economically sustainable recycling is a critical need. As manufacturers cut back costs and continue to look for ways to save money, the use of recycled plastics is high on the list for potential cost savings."

The American Plastics Council reports the number of plastics recycling businesses has tripled during the past 10 years, with more than 1,700 businesses handling and reclaiming plastics. The largest recoverer of post-consumer automotive plastics in North America, American Commodities Inc., has been looking for new methods to recycle what currently ends up in landfills or incinerators – more than 2 billion pounds of automotive plastics in 1999.

"A large fraction of this waste stream is composed of black plastics," says Mark Lieberman, chief executive officer of American Commodities Inc. "Automotive black plastics – from bumpers to instrument panels to fender liners – have several strikes against them when it comes to recycling. Mid-infrared spectrometers haven't been successful at analyzing them because of their unusual shapes and surface textures."

Mid-infrared probes, Grant explains, require flat reflective samples that are free of surface films.

Lieberman says American Commodities Inc. has been using SpectraCode's RP-1 spectrograph and plans to have it fitted with the new distributed focusing technology.

Founded in 1994, SpectraCode is a privately held venture with headquarters in the Purdue Research Park's business incubation complex. The company received initial funding to develop advanced Raman imaging systems through government research and development grants aimed at small technology companies. Grant says SpectraCode now operates with its own revenue, and the growing company hopes to double its existing staff this year.

Since 1993, Purdue Research Park's small-business incubation complex has launched more than 36 high-tech companies. Purdue's version of a business incubator provides start-up businesses with a shared office concept, flexible leases, attractive rental rates, shared office services and access to professional business assistance – including market analysis, networking and financial resources.