The Next Wave

Jul 18, 2017, 16:47 PM
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July/August 2017

Composites such as carbon fiber were created to last forever, meaning recycling was never part of the equation. Now, manufacturers and recyclers are working together to change that.

By Megan Quinn

Composites-GraphicFirst introduced during World War II, the lightweight composite material known as fiberglass gained popularity in the 1950s, when it started showing up in everything from kitchen sinks and bathtubs to boat hulls. It was called an engineering wonder—the material of the future. Carbon fiber, a different type of composite, soon found an even bigger fan base: The aviation and automotive industries use it alongside composite plastic parts as a strong, lightweight substitute for steel and aluminum to achieve better fuel economy.

Today, manufacturers still sing composites’ praises. “The reason composites work so well is because they’re very long lasting. They don’t come apart,” says Dan Coughlin, vice president of composites market development for the American Composites Manufacturing Association (Arlington, Va.).

Manufacturers sell an estimated 65,000 to 95,000 mt of carbon fiber a year, while fiberglass has an estimated worldwide manufacturing capacity around 5 million mt, says Ed Pilpel, senior technical adviser for the advanced composites group at PolyOne (Englewood, Colo.), a polymer formulator. And most experts agree the demand for composites is increasing, especially from the automotive, aerospace, and aviation sectors. Boeing, for example, recently invested $1 billion in a new manufacturing facility to build carbon fiber wings for its huge 777X model passenger plane, scheduled to take flight in 2020. Other major automotive and aviation companies are expanding their capabilities to add composite parts to their vehicles.

But composites’ most admirable quality is also their least sustainable. Durability “is the opposite characteristic you want when you need to recycle it,” Coughlin says. Composites are challenging to recycle because their interwoven fibers are difficult to separate from the resin or plastic that binds them together. Thus, more demand for composites—especially carbon fiber—also means more waste, and landfilling the material is costly and unsustainable. Though the technology for recycling composites is starting to improve, industry participants agree that more end use markets are needed to make the process worthwhile. That could change in just a few years, some say—but there’s lots of work to do to make that happen.

Composition of a composite

Composites consist of two basic elements: a high-tensile-strength stiffness fiber, such as carbon or glass, and a matrix that binds the fibers together, such as a resin or plastic, Pilpel says. Processors can recover fiber from composites made of either of two common types, known as thermosets and thermoplastics, but each has its own recycling challenges. Thermosets strengthen when they are heated, and they cannot be remolded once they are cured with heat and pressure. Thermoplastics soften when heated and harden and strengthen when cooled, similar to candle wax. “They are more readily recyclable because the matrix can be reformed,” he says. Both composite systems are great for high-heat applications (the bodies of Formula 1 race cars are made with carbon fiber thermosets, for example), but “typically, once you cook it, there’s no turning back,” Pilpel says.

Composites are relatively new products. Carbon fiber, for example, wasn’t invented until 1958, according to the U.S. Department of Energy. The composites industry is just now forging a stable recycling path and playing catch-up with commodities that have long been recycled. Those who want to recycle composites face the same challenges as those who recycle any other commodity: finding efficient ways to process the material, identifying the best end markets, educating consumers about the value of recycled composites, and making a profit. At this stage, Pilpel says, the value is in recovered carbon fiber, not glass fiber, resin, or plastic. Yet as recycling systems mature, resin and plastic might become more valuable as a fuel source for powering composite recycling systems, he says. According to a 2016 report from Composites UK, the composites trade association for the United Kingdom, recyclers have less interest in finding markets for glass fibers because of their low value. Some companies have sent glass fibers to waste-to-energy plants in Europe, but other glass fiber recycling initiatives “have been lacking,” the report states.

To jump-start composite recycling, Coughlin says, recyclers must refine their existing processing methods to reduce the cost of fiber recovery and increase the value of the material they produce to improve the bottom line. “There are technologies to recover fiber, but they are not in widespread use yet,” he says. “We want to encourage the development and commercialization of viable technologies.”

The recycling process

A few companies have what seem to be commercially viable methods for recycling composites, especially the carbon fiber. The two main methods for separating fibers from polymers are pyrolysis, a thermal treatment that burns away the resin, and solvolysis, which uses a heated solvent to break down resins.

ELG Carbon Fibre (Coseley, England) uses pyrolysis to recover carbon fiber. The company gets its material mostly in the form of postindustrial manufacturing scrap, such as composites left over from aerospace manufacturing. ELG typically takes “very few” end-of-life composite materials because the “business is in its infancy,” but it plans to handle postconsumer materials in the future, says Alasdair Gledhill, the company’s commercial director. “End-of-life products are not necessarily harder to recycle. It’s more that they are widely distributed in smaller lots so it is harder to accumulate them for processing as recycled products,” he says.

The materials enter the facility in chunks, which vary in size, thickness, and polymer type. Because of that variability, “it’s incumbent on the recycler to know what scrap we are dealing with and how best to process it efficiently,” he says. That’s part of why it’s less challenging for ELG to accept postindustrial scrap than postconsumer scrap: It can trace the material back to the original manufacturer’s specific batch and identify the type of material and polymers. Once it is identified, the material is shredded or cut into smaller sizes “using anything from high-tech shredders and milling machines to low-tech scissors,” Gledhill says. Then, the pieces move down a conveyor into a pyrolysis furnace, which burns off the plastic polymers and leaves clean carbon fiber behind.

ELG uses the fibers to make specification-grade recycled products such as nonwoven mats that a manufacturer can impregnate with epoxy or another resin and mold into products such as seats in automobiles, he says. The company also sells much smaller particles of recycled, chopped, and milled carbon fiber—“the size of grass seed”—that a buyer can mix with resin and make into pellets, which can be melted and used for injection molding. “The little pellets already have carbon fiber in them. They can be used to make any number of things—for example, car parts that require higher strength and lower weight at a price that is competitive versus alternative materials,” he says.

Pyrolysis works better on some sizes of carbon fiber than others, so the company also is looking into using a solvolysis treatment on some future products, Gledhill says. Another carbon fiber recycler, Vartega (Golden, Colo.), uses a patent-pending solvolysis process to recycle “high-grade [uncured] pre-impregnated scrap material, such as that used in the aerospace industry” and repurpose it into nonwoven fabrics, thermoplastic pellets, and even 3-D printing filaments, the company says. Its targeted end markets are aircraft interiors, automotive structures, wind turbine blades, and sporting goods. In an interview with the World Textile Information Network, President Andrew Maxey says Vartega does not yet recycle end-of-life carbon fiber products, only pre-preg from “large waste generators.” (Pre-preg is carbon fiber fabric that has been pre-impregnated with resin and the curing agent needed to create a hardened thermoset.) The company plans to dedicate “additional research” to processing postconsumer material in the future, he says.

Both pyrolysis and solvolysis are proven recycling methods, but recyclers have to be careful that either method doesn’t damage fibers and degrade the recycled products, says Chuck Ludwig, managing director of CHZ Technologies, a waste-to-energy company. It’s possible to recover carbon fiber from thermosets and thermoplastics, but because of their different chemical makeups, they need to be processed at different temperatures or with different chemical solutions. When using pyrolysis, for example, the cured epoxy in thermosets needs “a higher temperature, and it’s exposed a little longer” than polymers in thermoplastics, he says. Yet that high temperature might damage the fibers. According to the Composites UK report, pyrolysis typically results in a very good quality carbon fiber—exhibiting 90 to 100 percent of the properties of virgin material—but only when recyclers use “skilled control.” Pyrolysis also is the preferred method for separating glass fibers from fiberglass, since glass fibers “suffer degradation” in the solvolysis process, the report states.

Researchers are working on an experimental third process, thermolysis, which aims to use lower temperatures to precisely recover fiberglass or carbon fiber with “little or no” fiber degradation, Ludwig says. The ThermolyzerTM uses an externally heated reactor to separate shredded composite materials into a fiber fraction and a clean synthetic gas fraction. The gas, which meets natural gas standards, goes through a cleaning process to eliminate toxic components and then is used to power the Thermolyzer, he says.

The project, a joint effort of several recycling companies, the Energy Department, Oak Ridge National Laboratory, and researchers from the University of Tennessee at Knoxville and other universities, is in the testing stage at a plant in Germany, he says.

If the tests work, the Thermolyzer might be able to help solve another major composite recycling problem: recycling end-of-life materials. Ludwig claims the technology should be able to process “any and all” thermoplastic and thermoset polymers without causing damage to the fibers, meaning recyclers could begin recycling end-of-life products such as wind turbines.

Regardless of which method recyclers choose, Gledhill says they have room to improve their techniques in the coming years to be more efficient and help their bottom line. “We will get better over time as we build recycling experience,” he says.

Beginning with end markets in mind

As companies streamline the composite recycling process, they are also encouraging end users, such as automotive and aerospace manufacturers, to integrate more recycled composite materials into their products. To do that, Gledhill says, recyclers need to have a business case that specification-grade recycled materials perform at a level comparable to virgin materials—and cost less. Consumers “will have to realize the positive attributes of using a carbon-reinforced product. It’s super lightweight and strong, but the sticking point, historically, is that it is relatively expensive,” he says. “You have to educate the consumer that … the price point on a recycled [carbon fiber] product is very competitive compared to the primary carbon fiber price.”

As of spring 2017, the market values are there, assuming recyclers can process fiberglass and carbon composites to meet manufacturer specifications, Coughlin says. “Carbon fiber is worth several dollars per pound,” he says. Fiberglass is harder to market because glass has a much lower value and is heavier than its carbon counterpart, but recyclers that can efficiently recycle fiberglass can make a case for selling the recycled glass fibers, he says.

ELG recycles only carbon fiber products, and Gledhill says a target market for its recycled fibers is the automotive industry, which is motivated to make lighter-weight cars that will meet corporate average fuel economy standards, a U.S. regulation that requires manufacturers to improve the average fuel economy of cars and light trucks. “We see that industry is under pressure to adhere to CAFE standards,” he says. “Carbon fiber-reinforced plastics checks all those boxes.” It’s lighter than aluminum or magnesium, he says, lighter than glass fiber, “and mechanically stronger, too.”

Reuse, then recycle

About 30 percent of all carbon fiber produced becomes manufacturing scrap—about 15,000 mt a year, according to Vartega. The Composite Recycling Technology Center, a new nonprofit in Port Angeles, Wash., was created to spur recycling and divert this scrap from the landfill. CRTC invites carbon fiber consumers to donate their unused, uncured scraps instead of landfilling them. The organization has a goal to divert 1 million pounds of carbon fiber a year within five years. CRTC’s main feedstock is carbon fiber pre-preg from Toray (Tacoma, Wash.), a major composite supplier for Boeing. These thermoset scraps, which were manufacturing scrap from raw materials designated for Boeing’s 787 Dreamliner, haven’t yet been cured, so they can be laid into molds and heated to make a wide range of new products, such as pickleball paddles and park benches that won’t corrode in Port Angeles’ salty seaside breeze.

Geoff Wood, CRTC’s fellow and vice president of innovation, says part of the nonprofit’s work is finding creative and profitable ways to reuse carbon fiber, then sharing that knowledge with the composites industry. The nonprofit opens up its factory floor to any company interested in learning how to reclaim and use composite trim in its own factories and businesses.

Several companies already have consulted the nonprofit about manufacturing secondary products using carbon fiber and used the facility to do product development for such products, he says. “This is definitely an opportunity” to learn how to achieve 100 percent in-house composite recovery, he says.

BMW is one company that is reducing waste by integrating its excess carbon fiber into new cars, Coughlin says. Pieces of its 7-Series sedan are made from an epoxy sheet molding compound reinforced with recycled carbon fiber left over from both the 7-Series and moldings from its i3 and i8 hybrid and electric cars, according to Composites World. It’s a notable success story, Coughlin says, but one that isn’t always scalable. “BMW is large enough to do it on their own, but a lot of companies can’t,” he says. That’s where CRTC might step in to help, Wood adds.

Others in the automotive industry are interested in using this “zero-waste-to-landfill” approach, Wood says, and the aviation industry is close behind. Currently, CRTC can’t sell pre-preg back to aviation companies for use in the body of the plane because the quality doesn’t satisfy the Federal Aviation Administration regulations to prove the “custody chain” of carbon fiber scrap. In the near future, Wood believes more aviation companies will be interested in using the scrap for seats, cargo bins, or other non-fuselage features.

Aviation companies are starting to donate carbon fiber for non-aviation applications, Pilpel says. In 2016, Boeing announced it was working with Washington State University and the Washington Stormwater Center to research whether recycled carbon fiber composites could help strengthen permeable pavement, a type of porous paving material that can reduce stormwater runoff.

Other aviation-related companies market recycled composite products to compete directly with aluminum and steel, Pilpel says. One example is the Charleston, S.C.–based Cargo Composites, which has created air cargo containers made of composite fiberglass and polypropylene instead of the traditional aluminum. The containers are lighter and stronger than aluminum and last up to 10 years, the company says. When a container wears out, the company offers a free takeback program that will recycle every part. “It’s a whole life cycle deal for the airline. They see the overall economic benefit. The containers are lighter weight to begin with, so the airline can fill them with more cargo,” Pilpel says.

Forging relationships

Composite manufacturers have spent years perfecting the strongest, best composite materials, but they are now starting to address some of the lingering unknowns associated with recycling them, Coughlin says. Resin and fiber suppliers, composite manufacturers, end users, and recyclers—“everyone needs to be at the table to make this work,” he says.

Last year, the Institute for Advanced Composite Manufacturing Innovation formed to further advance the composites industry while also investigating and investing in recycling. The project is a joint effort among the Department of Energy, private composite companies, and the University of Tennessee, Knoxville. Pilpel, who sits on its technical advisory board, says IACMI has dedicated funding to help develop and test the Thermolyzer project.

ACMA also has taken strides to research recycling strategies for its members. Last year, representatives from ACMA approached ISRI for help learning about the basics of the recycling supply chain, which included meeting with recyclers from different commodity types, Coughlin says. “Some of the best meetings we had were with tire recyclers,” he says. Tires are “a composite, too—rubber and steel and fibers. You can’t landfill tires, so we asked them about their business model. They’re always looking for higher-value markets, and they know that the markets will change over time, and some parts [of the tire] will be more or less attractive,” he says.

ACMA will host its first composites recycling convention in April 2018 to bring composite industry players together for discussions of how to streamline and capitalize on recycling. Topics of conversation might include establishing standards for quality control, Coughlin says. Manufacturers “are asking, ‘If I’m going to use recycled fibers, who will qualify them?’ There are no standards right now for recycled fibers,” Coughlin says.

That question signals just how much the composite recycling conversation has matured in the past two years, he points out. In March, ACMA held a meeting of the Global Composites Recycling Coalition, a forum of composites recycling leaders from around the world, including other trade associations, OEMs, suppliers, manufacturers, distributors, and entrepreneurial recycling businesses, he says. It was the second such meeting in as many years, and a lot had changed since the group first met in 2016, he says. The first year, “everyone was asking, ‘How do I get these fibers out of composite scrap [economically]?’ But this year, the end user was saying, ‘I need a standard by which I can measure their quality.’ So that question just surfaced this past year, and it’s now on our plate.”

Gledhill says the market will help dictate which standards and specs are needed to sell recycled carbon fiber. Though in 10 to 15 years, when more end-of-life materials make their way into the recycling stream, “it might be useful to differentiate fiber that contains polypropylene, nylon,” or other polymers or epoxies. In terms of quality assurance, ELG is certified to AS/EN9100 aerospace standards because its customers like knowing the company has “full traceability of every fiber from the source to the finished product,” he says.

Another unknown, Coughlin says, is where traditional scrapyards can fit into the composite recycling world as more composite-heavy items, such as wind turbines, reach their end of life in the next 10 to 15 years. David Wagger, ISRI’s chief scientist and director of environmental management, says scrapyards might have a role as size-reducers “for when those big wind turbines come down in a few years. You might not know [the exact makeup of the material], but you could be the person to bring it down to a certain size,” he says.

Pilpel says composite recyclers still have a lot to learn from traditional recyclers who have been processing metals, plastics, and other commodities for years. Yet Wood adds that the composites industry must also share knowledge with scrapyards, especially to educate them about composites’ unique properties and their possible interactions with processing equipment. An auto shredder hoping to cash in on processing carbon fiber BMW i3 cars alongside more traditional aluminum and steel-framed cars “will have to make sure the auto shredder and related equipment can handle it,” he says. “Carbon fiber is highly conductive, so if there’s anything electrical, any motors in the area that are not fully protected, they will short out,” he says.

Though composite recycling is still a fledgling industry, Gledhill says the partnerships among manufacturers, researchers, and recyclers have already shown promise for its future. “For years, recyclers have proven they are up to the challenge for recycling everything, whether in up or down markets,” he says. “This is an opportunity for us to get into a new sustainable enterprise to innovate, grow, and globalize a new industry.”

Composites such as carbon fiber were created to last forever, meaning recycling was never part of the equation. Now, manufacturers and recyclers are working together to change that.

  • 2017
  • Jul_Aug

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