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Biopolymers: a green alternative to plastic textiles

December 1st, 2019 / By: / Feature

Bio-based materials are an increasingly desirable (and versatile) base for textiles in a variety of markets.

by Debra Cobb

Within global manufacturing’s quest to become more sustainable, biopolymers are becoming an increasingly important area of development. Polymers are the chains of monomers, or building blocks, that make up many materials, including textile fibers. Biopolymers—created from bio-based feedstocks—have the potential to replace petrochemical-based synthetics in a wide variety of products, including consumer goods and packaging, buildings and construction, automobiles and textiles.

As a building block for bio-TPUs (thermoplastic polyurethanes), Susterra is increasingly showing up in plant-based footwear, shown here from Vivo Barefoot. Photo: DuPont Tate & Lyle, ©Martin Scott Powell 2018.

Biopolymers can be derived from plant sugars and oils, such as corn, sugar cane, or castor beans; regenerated from cellulosic materials, such as wood pulp, algae or pineapple leaves; or created from the genetic modification and fermentation of microorganisms, mushrooms or even methane.

Only 11 percent of existing biopolymers are currently used for textile fibers, foams, resins and membranes. Most are used for consumer packaging.

A growing opportunity

The IDTechEx report “Biobased Polymers 2018–2023: A Technology and Market Perspective” by Dr. Bryony Core points out that global plastic production has grown exponentially from 1.5 million tons in 1950 to 335 million tons in 2016. The planet is virtually awash with nonbiodegradable plastics. While many traditional plastics can be recycled, thought leadership is increasingly turning to bio-based substitutes.

Biopolymers are usually nontoxic, often recyclable and sometimes compostable, making them highly desirable in a circular economy. Biopolymers can also be combined with traditional petrochemical polymers, creating new fibers with partial bio content at less expense.

Mango Materials uses methane and bacteria to create PHA biopolymers for fibers. Photo: Mango Materials.

According to a report by nova-Institute, a European research and consultancy group with a focus on the bio- and CO2-based economy, production of bio-based building blocks and polymers reached 7.5 million tons in 2018, and is predicted to grow at a compound annual growth rate (CAGR) of 4 percent through 2023.

The nova-Institute report, “Bio-based Building Blocks and Polymers—Global Capacities, Production and Trends 2018–2023,” describes biopolymers as having two advantages over traditional plastics: They replace fossil carbon in the production process with renewable carbon from biomass; and roughly 25 percent of them are biodegradable, offering a solution to plastics unable to be collected for recycling.

With only a 2 percent market share of the total plastics industry, biopolymers would appear to have a wide-open opportunity for growth, driven by an increasingly sustainable economy.

A complex value chain

The development and commercialization of any textile technology requires a complex value chain, deep pockets and a long-term commitment. Nova’s report sums up the challenges facing biopolymer commercialization: “Overall, the market environment remains challenging, with low crude oil prices and little political support.” Nevertheless, bio-based substitutes for petrochemical synthetics are increasingly important. Most are based on bio-monomers created by biotech companies and start-ups.

Based in the Netherlands, Avantium develops innovative technologies for bio-based monomers and polymers, collaborating with other companies to transition the manufacturing economy from fossil-based resources to plant-based chemicals and materials.

Avantium currently has three technologies at pilot and demonstration phase, according to Caroline van Reedt Dortland, director of communications. YXY plant-to-plastics–technology catalytically converts plant-based sugars into a wide range of chemicals and plastics, such as PEF (polyethylene furanoate), which has the potential to replace various packaging materials such as PET, glass or aluminum.

Avantium develops innovative technologies for bio-based monomers and polymers. Photo: Avantium.

“Avantium has successfully demonstrated our YXY plants-to-plastics technology to produce PEF at the pilot plant in Geleen, the Netherlands, and is planning to open a commercial flagship plant in 2023,” says Van Reedt Dortland. “However, textiles is a highly commoditized industry, for which only the price levels of PEF produced on an industrial scale will become of interest.

“We are currently working with partners to explore the future potential of PEF fibers in mainly high-value industrial fibers,” she says.

Avantium’s second project is the Dawn Technology™ that converts nonfood biomass into industrial sugars such as glucose, which is a core building block for many bio-based products and is increasingly important in the transition towards a circular economy. “All materials made from petroleum today, such as bottles, polyester clothing and carpets, can be replaced with materials made from industrial sugars,” Van Reedt Dortland points out.

The third technology, Mekong, is reported to have strong commercial potential. Mekong catalytically converts industrial sugars to plant-based MEG (mono-ethylene glycol). MEG is a component for making everyday consumer goods, such as PET and PEF plastics and polyester textiles.

Avantium recently received a €6 million grant from SPIRE, the European Union’s subsidy program to facilitate the sustainable process industry.

Mango Materials, Redwood City, Calif., established in 2010, uses methane and bacteria to create its versions of polyhydroxyalkanoates (PHA). The company has joint development agreements with well-known, forward-thinking companies.

Textivision’s glossy knit jacquard features biobased Naia™ and elastane. Photo: Eastman Chemical Co.

“Currently we are optimizing our formulation for fibers and conducting numerous melt spinning trials,” says Dr. Molly Morse, company CEO. “Finding the optimal combination of melt processing, material property and environmental attributes and designing for next use is a work of art. Different types of melt spinning equipment and configuration can influence these properties, so it is quite some effort to work through the supply chain.”

Morse feels that Mango’s biggest challenge is the industry’s lack of familiarity with PHA. “It is still considered a new material,” she says, “and a lot of education is required to get everyone up to speed and to understand the optimal processing conditions and techniques. Biopolymer textiles made from low-cost feedstocks can ultimately be competitive with petroleum-based persistent textiles—the key is achieving large scale. We believe methane offers the best opportunity to bridge the current pricing gap between biopolymers and traditional plastics.”

Biopolymers in commercial use

PLA, or polylactic acid, was the original melt-processable biopolymer produced from renewable resources, such as corn starch, which is converted to glucose and then to lactic acid. Commercialized in the 1990s as Ingeo™ by Cargill-Dow, it was not especially successful in apparel textiles. PLA has been well-received for bedding and fiberfill, and is widely used for packaging.

PTT or Triexta (poly trimethylene terephthalate), another substitute for polyester, is created from Bio-PDO, a bio-monomer developed by DuPont in Wilmington, Del. Bio-PDO (1,3-propanediol), branded as Susterra®, is the result of the aerobic fermentation of glucose; it’s reacted with a petrochemical monomer to create PTT. The resulting polymer, branded as DuPont Sorona® for apparel and carpet, is 37 percent renewably sourced. (The U.S. government requires only 25 percent for an official bio-based label.)

Bio-based Tencel fibers are seeing strong growth in various textile markets. Photo: Lenzing AG.

The Sorona brand team is rolling out a new brand architecture in 2020 focused on fabrics to make it easier for apparel brands and garment manufacturers to find the solutions they’re looking for, according to Laurie Kronenberg, global marketing manager for Sorona, DuPont Tate & Lyle Bio Products Co. LLC.

Sorona polymer-based fabrics and insulation products offer a wide variety of performance solutions for apparel manufacturers: wrinkle-resistant outerwear fabrics, spandex-free stretch fabrics and long-lasting stretch fabrics that maintain their shape wear after wear, as well as soft and resilient solutions from natural fiber fabric binds to insulation and even new faux furs.  

“People buy our product based on performance,” says Kronenberg. “We are happy to provide brands with different ways to move towards a circular economy.”

DuPont Tate & Lyle continues to expand its production of Susterra Bio-PDO as well. As a building block for bio-TPUs (thermoplastic polyurethanes), Susterra is increasingly showing up in plant-based footwear, apparel and gear as it integrates into existing manufacturing processes from traditional injection and cast molding to newer 3D printing processes, says Kronenberg.

Norafin’s ecological nonwovens include this wallpaper made from flax. Photo: Norafin®.

A new spin on cellulosics

Wood-based cellulosic fibers such as rayon, acetate and lyocell have been around for years. Now repositioned and marketed as sustainable and biodegradable options, the branded cellulosic fibers Lenzing TENCEL™ and Eastman Naia™ are both enjoying success in the apparel textile market.

For more than a decade, the total production of wood-based cellulosic fibers has outperformed the market, and should continue with a growth rate of 5–6 percent, according to Filip Miermans, vice president of corporate communications and investor relations for Lenzing AG, a global group headquartered in Austria.

He explains that the biggest share of wood-based cellulosic fibers is targeting the textile industry for apparel, innerwear and home goods. The nonwovens industry, with applications for wipes and hygiene products, is also growing.

Tencel fibers are created from wood pulp from natural forests and sustainably managed plantations. All Tencel fibers are available with FSC® (Forest Stewardship Council) certification or PEFC™ (Programme for the Endorsement of Forest Certification) upon request, and have been certified as bio-based under the BioPreferred® Program of the U.S. Department of Agriculture (USDA). The water and chemical solvents used in their manufacturing process are recycled and reused.

Miermans says that sustainability is taking on momentum alongside the key attributes of function and performance. “We will strongly focus on transparency (traceability of fibers) along with partnerships along the value chain to further innovate, and on marketing and co-branding initiatives.”

Acetate, the “forgotten” wood-based cellulosic fiber, has recently re-entered the market as Eastman Naia, with a sustainable profile and positioning. Launched in 2017, the brand already has more than 100 partner mills producing sustainable fabrics for apparel brands around the world.

Ruth Farrell, Eastman Chemical’s global marketing director for textiles, describes Naia as “quite unique in the world of cellulosics.” The company, based in Kingsport, Tenn., sources from collaborative pulp suppliers who conform to the FSC and PEFC standards; and Naia is certified as bio-based by the USDA. 

“Demand is coming from brands who are looking for yarns that have a good origin and end-of-life story,” says Farrell. “Naia delivers on both. The manufacturing process for Naia is closed loop, using no hazardous chemicals.”

Farrell points out that Naia has an expanded range of deniers and excellent handfeel, drape and luster; it responds well to aesthetic treatments such as printing, pleating and calendering. The brand is focused on women’s wear, intimates, sleepwear, loungewear and linings as primary markets. “Naia has the ultimate ability to be a mainstream brand,” says Farrell.

Vestera™ cellulosic fiber is Eastman’s acetate brand targeting the nonwovens industry. Like Naia, it’s made from wood pulp from sustainably managed forests, processed in a near-closed loop system, certified as bio-based by the USDA, and is biodegradable.

Vestera is just one of the bio-based fibers used at Norafin Industries, a venerable nonwovens manufacturer with facilities in Mills River, N.C., as well as in Germany. Norafin began using flax fibers for its spunlaced nonwovens in 2006; the company’s development of “ecological nonwovens” is being driven by demand from the market and customers, according to Norafin business director Stuart Smith.

In addition to flax, the company is using FSC-certified rayon and acetate, as well as cotton. Bio-based PLA products are also in development, although not yet commercially available. The emphasis is on processing natural fibers without chemical supplements, using ecological finishing for industrial performance applications.

“Sustainability is a big focus across several of our business units, including home furnishings, personal care, cosmetic applications, wipes and cleaning,” Smith explains. “In North America, we see the market moving more and more toward sustainable solutions. It’s a good fit for Norafin.”

Not easy being “green”—so far

It’s no surprise that commercially successful biopolymer-based textile products such as DuPont Sorona, Lenzing Tencel and Eastman Naia have benefitted from being launched by established textile firms.

Biotech start-ups continue to persevere, raising hopes for the next viable—and affordable—alternative to petrochemical textiles.

In the IDTechEx report, Dr. Core reports: “Although some of these types of polymers have been well known for over a century, they have not yet seen widespread application due to barriers facing production, such as cost and scale. However, thanks to innovations in synthetic biology, these polymers are becoming more affordable to manufacture, and therefore more commonly encountered.”

“We believe biopolymers are critical to keeping our natural environment pristine and transforming the plastics industry into a closed-loop system. Biopolymers are no longer just a nice-to-have—now they are a need-to-have,” reiterates Mango Materials’ Dr. Molly Morse. “From our partnerships, we know exciting developments are on the horizon. It’s clear now that biopolymers are here to stay.” 

Debra Cobb is an expert writer and editor based in Greensboro, N.C. 

SIDEBAR: Creepy, crawly, slimy . . . fabric

Scientists at the U.S. Navy are synthesizing hagfish slime. Photo: U.S. Navy.

Biopolymers can be created from the strangest things: orange peel, mushrooms, pineapple leaves, spider silk—and even hagfish slime.

Like something out of a science-fiction movie from the ‘50s, the hagfish, also known as a slime eel, looks prehistoric. When threatened or attacked, it produces prodigious amounts of “slime” made up of long fibers of glycoprotein that are stronger than nylon and thinner than human hair, much like spider silk. The fibers expand rapidly to envelop and neutralize any attacker.

Scientists believe hagfish slime’s strength, flexibility and expandability could be the basis for innovative biopolymers that could substitute for nylon in protective and industrial applications, from safety vests and helmets to airbags. Hagfish cannot be raised in captivity, however, so researchers at Canada’s University of Guelph, as well as the U.S. Navy, are looking into ways of synthesizing slime in the lab.

Mylo bio-based leather from Bolt Threads is made from mycelium. Driver bag shown is by Chester Wallace. Photo: Bolt Threads.

According to the journal Interesting Engineering, in 2017 Navy biochemist Dr. Josh Kogot and materials engineer Dr. Ryan Kincer developed a synthetic slime that mimics the hagfish mucus. The researchers created the slime by genetically modifying E.coli bacteria to produce the alpha and gamma proteins present in hagfish slime.

In the arachnid arena, Bolt Threads uses DNA and fermentation to create synthetic spider silk, which can be spun into a fiber called Microsilk. The company’s latest creation is Mylo, a synthetic leather made from mycelium, the root structure of mushrooms. Both Microsilk and Mylo have been showcased in products by high-end fashion designer Stella McCartney.

Japan’s Spiber Inc. is also successfully synthesizing and tailoring spider silk proteins from DNA through fermentation. The company’s protein fiber, called Qmonos, is targeted at the automotive industry as well as the apparel market.

The Lexus Kinetic Seat Concept uses Spiber’s tough, eco-friendly Qmonos synthetic spider silk in the backrest. Photo: Lexus.

SIDEBAR: Sweet sustainability

Carnegie Fabrics’ bio-based Xorel® polyethylene (PE) claims to be the first high-performance interior textile derived from a majority of plant-based content. Seven years in development, Xorel is derived from sugar cane, which is crushed, fermented and distilled into ethanol, and then transformed into polyethylene, extruded into yarn, and woven into beautiful wallcoverings and interior textiles. Bio-based Xorel fabric contains between 60 and 85 percent sugar cane, depending on the pattern.

Ethanol can be distilled from a variety of sources, including oil, natural gas, corn and sugar cane. While corn is cheap, sugar cane is especially effective in sequestering carbon; its roots continue to store carbon even after the plant is harvested.

A certified B-company, Carnegie has tested and certified Xorel for performance as well as for safety and environmental impact, and the product has achieved points in multiple LEEDS categories

Twine, a wallcover pattern by Carnegie Fabrics, features biobased Xorel®, sourced from sugar cane. Photo: Carnegie Fabrics.