Laser vision

Properly identifying plastic by resin type is a key to profitability for brokers, recyclers and reprocessors of plastic scrap. Some brokers and recyclers can find that misidentified loads of plastic scrap can be a costly mistake. These costs can involve overpayment for the load, returned shipments and additional sorting costs, as well as serving as a blow to the seller’s reputation, says Todd Hardwick, TSI/ChemLogix senior global marketing manager.

TSI, based in Shoreview, Minnesota, has introduced a handheld device that the company says can accurately identify a wide range of plastics, including light and dark plastics.

As Hardwick says, TSI researched existing methods for identifying recycled plastics. The manufacturer of precision measurement instruments learned that some recyclers have long relied on a technique referred to as “burn and sniff,” where a recycler lights the plastic on fire, takes a big whiff and attempts to identify the plastic on the spot based on the scent that results. Hardwick says this “judgment call” does not offer an accurate identification of all plastic materials.

Unlike handheld sorters used to identify metals, which typically use X-ray fluorescence (XRF), the PolyMax™ plastics analyzer is laser-based. The measurement is accomplished with point-and-shoot effort by shining a laser on the sample material and collecting a spectrum of the reflected light, Hardwick says. The spectrum is generated based on the chemical composition of the plastic, which is unique to each resin. The fingerprint is then compared with a library of fingerprints and the analyzer displays the best match for the plastic.

In the Q&A that follows, Hardwick explains how the PolyMax instrument fills a void in the marketplace by identifying a range of plastics, including black plastics, in nearly any form.
 

Recycling Today (RT): Why did TSI introduce the Polymax plastics analyzer to the market?

Todd Hardwick (TH): Following extensive research of existing methods for identifying recycled plastics, it became clear to TSI that there was demand for a more robust, handheld solution. In particular, we learned that one of the accepted methods for recycled plastics identification in the field is known as “burn and sniff,” which is based on a judgment call and does not provide a confident identification of all plastic materials all of the time.

On the other hand, laboratory analysis of plastics or sending plastics to a third party for identification is expensive and time consuming.

Finally, existing field-based instruments only [identify] a subset of plastics and can generally only identify light-colored plastics.

As such, brokers and plastic recyclers have long sought an instrument that provides a relatively quick and easy ID reading that is accurate and consistent for all of the plastics they encounter, including black plastics—a need in the marketplace we have worked to fulfill by introducing the PolyMax plastics analyzer.

The PolyMax analyzer is a tool that will now provide a reliable ID reading for the plastics that plastics recyclers and brokers [encounter], and we have already seen an extremely positive reaction from the marketplace verifying the need for the PolyMax analyzer.
 

RT: What types and forms of plastics can the PolyMax identify? What is the value in identifying a variety of plastics?

TH: The PolyMax analyzer will detect a wide variety of plastics in any form from all major families and subfamilies of plastics: polyethylene (PE), polystyrene (PS), nylon, polyvinyl chloride (PVC), polycarbonate (PC) and polypropylene (PP). The analyzer can even distinguish plastics that are very similar, including high-density polyethylene (HDPE) versus low-density polyethylene (LDPE); nylon 6 versus nylon 6.6; and acrylonitrile butadiene styrene (ABS) versus styrene acrylonitrile (SAN).

To date, our instrument library contains more than 100 different plastics—a number that is growing. The instrument will analyze materials in nearly every form, whether it is in rolls, bales, flakes, sheets, pellets, scraps, bottles, pallets and/or purge.

Moreover, the PolyMax works for all colors of plastics, which, again, distinguishes it from alternative field-based instruments.

The capabilities of the analyzer provide significant value to the user by being able to analyze the majority of plastics a recycler or broker will encounter and allow the broker to make confident buying and selling decisions on loads of plastic, in turn maximizing his or her profit and minimizing costly mistakes.
 

RT: How does the PolyMax “take the guesswork out of plastic identification?”

TH: The PolyMax instrument is a laser-based plastic analyzer that relies on science, not scent or other subjective measures, to ID plastic materials. The measurement is accomplished with point-and-shoot ease, so anyone and everyone who uses it will obtain consistent and accurate readings.

The analyzer shines a laser on the sample material and collects a spectrum or fingerprint of the reflected light. The spectrum is generated based on the chemical composition of the plastics and is unique to each material. The fingerprint is compared to a library of fingerprints and displays the best match or the ID of the plastic.
 

RT: What technology does the analyzer employ?

TH: The PolyMax employs Raman spectroscopy to analyze the plastic materials.

Raman spectroscopy is a well-established technology that has been around for nearly a century that is used to ID a variety of materials, ranging from polymers and pharmaceuticals to explosives and pigments, as well as other materials.

TSI has developed the PolyMax to provide a portable, accurate ID of both light and dark plastics using this technology.
 

RT: How are recyclers or brokers using the analyzer in their operations? What benefits are they seeing as a result?

TH: Plastic brokers utilize the PolyMax analyzer to make accurate buying and selling decisions of large quantities of recycled plastic materials. This eliminates the cost of mistaken identifications, including paying too much for the material, shipping costs and unexpected sorting costs. The broker will utilize the Polymax to verify purchases before pickup, allowing the broker to reject nonsorted loads or loads that are identified incorrectly.

The PolyMax analyzer can be used by recyclers or manufacturers to verify the ID of the incoming plastics material, which in turn ensures the quality of the material and prevents costly recalls.

Finally, the handheld analyzer also can be used to spot check the recycled plastics sorting process and ensure it is being done correctly.
 

RT: Does the material need to be prepared in a certain way to get an accurate reading?

TH: The PolyMax analyzer hits the plastic with a focused laser beam to collect the spectrum of the signal emitted from the plastic material. As such, the material should be reasonably clean with coatings scraped away to provide access to the plastic and avoid interfering readings.

The instrument also comes equipped with swappable sampling adapters to accurately and easily analyze plastic pellets, films and sheets.
 

RT: How much time does it commonly take to get an analysis? What factors affect this?

TH: The sampling time will range from five seconds to about 60 seconds, depending on material type; the instrument automatically determines the sampling time to get an accurate result.

Measurement of light-colored samples can be conducted in five to 20 seconds, while black or dark samples will take about 60 seconds. Additionally, some plastics have bright-color dyes that lead to fluorescence, which also may take around 60 seconds for a measurement.
 

RT: Does the PolyMax offer the same reliability across multiple plastics colors?

TH: The analyzer will give a proper ID for most plastics. Dark color or plastics with fluorescent dyes are more difficult to measure, require longer sampling analysis times and may impact the reliability of the measurement, depending on the material.

The identification also displays a “score” that provides further clarification of how confident the instrument is in the reading.
 

RT: Prior to the introduction of TSI’s PolyMax analyzer, how have those working with plastics traditionally identified this material?

TH: The most common method for identifying plastics in the recycling industry has been through a series of more subjective procedures, most notably, the burn-and-sniff method in which a small sample of the plastic is lit on fire and the odor and other physical indicators of the burn are used to decide what the plastic material is.

Experienced users can make an accurate determination using this method, but it is still a judgment call, and some plastics are very difficult to determine this way.
 

RT: In what ways can users of the PolyMax customize the analyzer to their operations?

TH: The PolyMax analyzer has a standard library of plastics but also comes equipped with a customizable user library that can be updated by customers to include specific plastics that they see in their operations. This can be utilized to analyze mixed plastics or plastics with additives or fillers that are not part of the standard library and makes it a powerful feature for PolyMax analyzer owners.
 

RT: What is a typical ROI (return on investment) for an analyzer of this type?

TH: Mistaken identifications of loads of plastic are costly. These costs can include overpayment for the load, return shipments, additional sorting costs, plus damage to the reputation of the seller. The Polymax will pay for itself by preventing two to three mistaken identifications by the broker or recycler.

Megan Workman is associate editor of Recycling Today and can be contacted via email at mworkman@gie.net.