Encore! Demand for sustainable resins drives development of innovative recycled and biobased materials.
Engineers and chemists have worked for years to find uses for mechanically recycled plastics. Success stories include using polyethylene from post-consumer recycled grocery bags to make wood-plastic composite lumber and recycled polyethylene terephthalate (PET) bottles to make fibers for fabrics and carpet.
Work is also underway to improve the process of mechanical recycling and the quality of recyclate. The lower properties of post-consumer recyclate (PCR) compared with virgin resin have relegated its use to being part of a blend where its lack of quality can be controlled. Some materials developers, though, seek formulations with a more circular use, so PCR can replace virgin resin, possibly even in the same product. With some successes under their belt, virgin resin producers have started supplying recycled resin grades with improved properties.
Braskem's new "I'm Green" recycled polypropylene, for example, is made from polypropylene (PP) twine typically used for hay bales. Braskem recompounds and pelletizes the twine, which it dyes black for color uniformity. The 100 percent recycled PP reportedly has properties similar to virgin PP and can be used in automotive parts and consumer products.
Dow's Agility CE is a low-density polyethylene (LDPE) grade for case-wrap shrink films that contains 70 percent PCR from shrink wrap collected from retailers. This product allows a high degree of recycling material back to the same application, which ensures a consistency and quality that had been difficult to achieve, says Victor Zapata, Dow's recycling commercial director for Latin America and North America. "In flexible packaging applications, the two biggest growth markets for PCR are stretch and shrink packaging and consumer goods, both driven by consumer demand as well as application performance needs."
He predicts that supply availability and quality of PCR would improve as collection and sorting systems and new cleaning technologies are implemented. Zapata points to a partnership between Dow and Avangard Innovative (Al) to supply PCR-based linear low-density PE (LLDPE) and LDPE as an example of how to meet industry goals. "Our companies work together alongside Dow's brand owner and converter customers to commercialize PCR-based innovations with Dow materials here in North America," explains Zapata. Al collects and sorts PCR film, which it processes into pellets that will initially be used for LLDPE and LDPE products such as waste-bin liners and shrink wrap. Zapata says this is a first step in achieving advanced PCR-based innovations.
The Chemical Recycling Alternative
An alternate approach to the limitations of mechanical recycling is chemical recycling (also called advanced recycling). In this method, thermochemical processes such as pyrolysis and depolymerization are used to make plastics waste into secondary raw materials like pyrolysis oil and monomers. Pyrolysis is not the same as incinerating waste to produce energy; the pyrolysis process results in oil that can be purified and used as raw material in chemical production of resins, thereby replacing fossil fuels, such as naphtha. Because secondary raw materials from this chemically recycled source have the same properties as fossil fuels, they can be used to make virgin-grade products.
Chemical recycling processes are not all the same, says Joe Vaillancourt, CEO of Agilyx, a chemical recycling company in Tigard, Ore. In addition to a range of equipment types and process variables, the chemistry of the recycled feedstream affects the process. "Managing the complexity of these waste streams is a challenge," says Vaillancourt. Agilyx has a solution to this challenge, developed over the past 15 years of operation. "We receive and preprocess a wide range of plastic sources--from manufacturing waste to PCR yogurt cups to fish boxes and agricultural trays with fertilizer contamination--and use our quality control and recipes to make a consistent product."
"We are not homogenizing at the source, which is what mechanical recycling does. We can process all plastics, even with contamination, but we need to know what is in it," he says. The company characterizes the chemistry of incoming materials and uses predictive modeling for what these materials can be used for. In December, Agilyx announced a partnership with GE to apply artificial intelligence to enhance its modeling capability.
Agilyx started out in fuel production, then migrated to converting polystyrene (PS) waste to styrene monomers. The company also developed a mixed plastics-to-naphtha pathway. Agilyx has multiple products in fuels, polymer-to-polymer, and chemical substrates. The company is expanding beyond its first PS-to-monomer process in Oregon and is partnering with PS manufacturer INEOS Styrolution to build a facility in Illinois to process up to 100 tons per day of PCR PS into styrene monomer. Agilyx is also collaborating with INEOS Styrolution and Trinseo to build a PS chemical recycling facility in Europe that will be capable of processing up to 50 tons per day of post-consumer PS, including food packaging.
BASF, which started its ChemCycling program in 2018, says the project is complementary to mechanical recycling and focused on waste for which there is not a high-value mechanical recycling process, such as mixed plastics, multilayer food packaging, or some composites. The project is initially focused on Europe and on chemical recycling by pyrolysis.
Although chemical recycling is an established technology, its use as a plastics recycling option is relatively new, and broader acceptance is important for its wider use. In Europe, although there is not outright opposition in current legislation, there are regulatory ambiguities, according to BASF.
"While the legislative framework of the European Union builds on a technology neutral definition of recycling, chemical recycling is not yet recognized as a process that contributes to fulfilling the plastic packaging waste recycling targets in Germany. This sends the signal that chemical recycling is a second-class option, similar to energy recovery," BASF says. "Acceptance for attainment of recycling targets would be an important political signal. Similarly, incentives for recycled content should be applicable to all forms of recycling."
Acceptance of certified mass balance approaches is another key to the progress of chemical recycling. "We are optimistic that by demonstrating technology, market demand, and environmental benefits, we can provide good arguments why chemical recycling should be seen as a valuable addition to a circular economy and should meet supportive legislative conditions," adds BASF.
In 2019, BASF partnered with Quantafuel, a Norwegian startup that specializes in the pyrolysis of mixed plastics waste and purification of the resulting oil. Quantafuel is expected to start up a pyrolysis and purification plant in Denmark this year. Pyrolysis oil and purified hydrocarbons from Quantafuel will be used at BASF's Ludwigshafen, Germany, site to partially replace fossil feedstocks and deliver the first commercial products based on chemically recycled plastics to select customers. BASF uses a certified mass balance approach to allocate a percentage of the recycled raw material to its Ccyded chemically recycled products, which will include polyamides and polystyrene.
BASF explains that although it is not possible to trace individual molecules through the many reaction steps required to manufacture a chemical product, with the mass balance approach, the percentage of recycled materials can be allocated to certain products. A similar principle is used to quantify electricity from renewable sources. "Although consumers cannot be certain that the electricity they use in their homes has come directly from renewable sources, the overall share of green energy in the grid rises in step with demand," explained the company in a statement.
Other chemical recycling partnerships are starting up, such as Dow's partnership with the Fuenix Ecogy Group based in Weert, The Netherlands. Fuenix supplies pyrolysis oil made from recycled plastics waste.
Eastman's Carbon Renewal Technology, launched in 2019, is a chemical recycling process that reduces plastics waste to molecular components (carbon, oxygen, and hydrogen). One of the feedstock sources is a collaboration with post-consumer waste reclaimer Circular Polymers of Lincoln, Calif., which will divert millions of pounds of carpet from landfills in its first year, according to Eastman. In February, the company's process won the Plastics Industry Association's Refocus Sustainability Award for end-of-life innovations. Eastman's polyester renewal technology (PRT) is chemical recycling specifically for PET. "Closing the loop of waste plastics is a complex problem that has to be solved with innovative solutions," said Mark Costa, board chair and CEO of Eastman, in a press release.
These processes show that closed-loop plastics recycling is possible. Although some argue that chemical recycling is energy intensive, industry experts are working on lifecycle analyses for chemically recycled products. Other detractors say that chemical recycling does nothing to reduce society's dependence on single-use plastics, but supporters say it will increase recycling rates by making more post-consumer plastics waste recyclable.
"As consumer behaviors change and as consumer product goods change, we can adjust our chemical recycling process accordingly," says Vaillancourt. "It's not logical to think society is not going to use plastics; our mission is to help the plastics industry globally achieve a 95 percent recovery rate for plastics."
Biobased plastics have struggled over the years for various reasons, including the challenge of competing with the lower cost of petrochemical-based virgin polymers. The renewed interest in sustainability, however, is creating demand for bioresin alternatives. For example, LEGO began making some of the elements in its toy building block sets from Braskem's sugarcane-based polyethylene (PE) in 2018 and has a goal of making all its toys with sustainable materials by 2030. Beginning this year, Mattel's Fisher-Price Rock-a-Stack toys will be made with sugarcane-based PE, and the company is also launching Mega Blok sets made from biobased plastics.
Finland's UPM Biofuels uses residue from wood-pulp processing to make biobased naphtha, a crackerfeedstock for biobased ethylene. Dow is using the feedstock to make biobased PE at its facility in The Netherlands. In February, INEOS signed a long-term supply agreement with UPM to use the biobased naptha to make BIOVYN bio-attributed PVC at its facility in Cologne, Germany.
DSM has launched bio-based grades of its Arnitel and Stanyl engineering resins made using a mass-balancing approach. The company says that by 2030, it will offer all its resins with at least 25 percent recycled and/or biobased content using a combination of mass balancing, mechanical recycling, and other technologies.
Replacing fossil fuels with biobased hydrocarbons in polymer production results in polymers that are identical in properties to conventional virgin resins, making them dropins to existing products and processes, but not biodegradable or compostable. Other types of biobased polymers like polylactic acid (PLA) and starch-based polymers are not drop-ins but may be compostable or biodegradable. These are finding use in short-term, single-use products, such as food-service items and bags.
For example, BASF's ecovio, which is a ready-to-process blend containing biobased PLA polymer and BASF's biodegradable (but fossil fuel-based) ecoflex polyester polymer, is certified compostable and being used for single-use products such as food cling film, bags, and agricultural film. Compostable plastics are a growing niche market, noted BASF, as several countries in Europe have mandated separate organic waste collection and passed legislation that fruit and vegetable bags be compostable. BASF reported that such bags extend shelf life and can be used for transporting food and increasing food waste collection for composting.
"Plastic lost to the environment as waste is a major problem, and it's something that's driving us toward new possibilities across our operations," says Zapata of Dow. The company's activities in chemical recycling, PCR, and closed-loop recycling of shrink films are examples of collaborative efforts to build sustainable technologies and capabilities that will keep the industry moving toward a circular economy for plastics.
"We're engaged in the transition from a linear economy to one that redesigns, recycles, reuses, and remanufactures to keep materials at their highest value use for as long as possible," Zapata notes. "The result is a circular economy that makes the most of our natural resources and ultimately reduces the amount of waste that goes into landfills."
Jennifer Markarian is a contributor for Plastics Engineering and other industry publications. A Penn State chemical engineer, she began her plastics industry career with Mobil Chemical's polyethylene group in product development and technical service and, after seven years with Mobil, started a freelance technical writing and editing business, Technical Writing Solutions LLC. An SPE member since 1999, she serves as newsletter editor for SPE's Palisades-New Jersey Section. She can be reached at email@example.com.
Caption: Mattel's Fisher-Price Rock-a-Stack toy is made from sugarcane-based bioplastics. Courtesy of Mattel
Caption: Dow is partnering with Avangard Innovative to supply PCR-based LLDPE and LDPE grades made from recycled film. Courtesy of Avangard Innovative.
Caption: Perwoll bottles made by Henkel and Alpla incorporate chemically recycled plastic supplied by BASF's ChemCycling project. Courtesy of BASF.
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|Title Annotation:||SUSTAINABILITY MATERIALS|
|Date:||May 1, 2020|
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