Manmade Cellulosic Fibers (MMCF)—A Historical Introduction and Existing Solutions to a More Sustainable Production

Abstract

Forecasts of the use of manmade cellulosic fiber (MMCF) like viscose suggest a rise in the next few years, due to its performance and price compared with other fibers. MMCF, such as viscose/rayon, lyocell and modal (as well as cupro and acetate), are the second most important group of cellulosic fibers after cotton, with an average annual demand of 5–6 million tons. MMCF is produced from natural feedstock such as trees and plants using a chemical process, unlike cotton. Recent reports from non-governmental organizations (NGO), like Canopy. On the nature of viscose production, covering the sourcing and origin of feedstock, the threat to endangered species and environmental pollution created by the pulp and fiber production process, raised awareness among textile and apparel companies. Dissolved pulp used for MMCF production, sometimes from controversial or illegal sources, is transformed or regenerated into fiber by a water, chemical and energy intensive, multiple step process using highly toxic chemicals. Although the process is more than 100 years old, the industry still relies on the very same kind of toxic chemicals considered dangerous for the environment and humankind. The production of lyocell fiber uses a different chemical process which is considered eco-friendly. In their 2017 and 2018 reports, the Changing Markets Foundation claim that the Viscose industry is using non-sustainable feedstock and that fiber production in Asia heavily pollutes the environment and is endangering human health. One life cycle assessment (LCA), commissioned by the brand Stella McCartney, evaluating the impact of ten different variants of MMCF global production, it was concluded that the current viscose production system carries very different but serious risks. All this underlines the need for a more sustainable sourcing of feedstock for dissolving pulp as well as more sustainable production processes for MMCF that include alternative feedstocks, better control and efficiency of inputs as well as a better management of the manufacturing process, including waste water, solid waste and air emissions. Alternative feedstock and recycled feedstock include pre- and post-consumer textile waste but also non-textile feedstocks such as agricultural residues or even manure. So far alternative feedstocks play a marginal role. Even though technologies seem ready, a significant investment is required scale them to a commercial level. The following chapter will reflect on the pros and cons of MMCF production processes and will provide some possible solutions to a more environmentally friendly future for MMCF. This chapter cannot claim to be complete nor comprehensive. In a constantly evolving industry, we highlight some relevant innovations where industry success and scaling potential still needs to be proven. It is imperative that more scientific data on sustainability attributes and impact on the environment, through independent LCAs, for example, need to be gathered in order to allow assessment and better comparability.

A practitioner’s perspective

1 A Historical Overview—Manmade Cellulosic Fibers

Manmade fibers are fibers where the basic chemical units have been formed by chemical synthesis from crude oil followed by fiber formation or are made from carbon, ceramic, glass or metal. These fibers are called manmade synthetic fibers.

Manmade fibers can also be obtained from polymers of natural sources after dissolving and regenerating subsequent to passage through a spinneret to form fibers. Such fibers include viscose, lyocell, modal, acetate and cupro and are generically known as manmade cellulosic fibres (MMCFs).

Due to the increasing need for silk in order to serve the growing demand for silk textiles, scientists around the world tried to develop a material with similar characteristics to silk but that was less expensive in an attempt to become independent from the Chinese and Indian silk market. In 1664, the English naturalist Robert Hooke published a theory that artificial silk filaments can be spun from a substance which is similar to the one silksworms use to make silk. Based on Hooke’s theory, scientists (Swicofil 2018) tried to develop an artificial silk, but no one succeeded. It took another 200 years until George Audemars discovered the first crude artificial silk around 1855 by dipping a needle into a liquid mulberry bark pulp mixed with gummy rubber. However, since this method was slow, it never developed on commercial scale. Thirty years later Hilaire de Charbonnet, a French chemist, patented an artificial silk which was the first known cellulose-based fabric. Although attractive to look at and comfortable, it was very flammable and therefore removed from the market (Bellis 2008). The British inventors Charles Cross, Edward Bevan and Clayton Beadle finally developed and patented a methodology for producing artificial silk that came to be known as viscose rayon (Shaikh 2012). The name rayon was derived most probably due to its brightness and structural similarities to cotton (Shaikh 2012) (Sun =  ray and on = cotton). The name viscose comes from the Greek word viscous and describes a gummy liquid of sticky consistency, referring to the honey-like spinning solution used within viscose process from which the fibers are made. Therefore, viscose fiber is considered the oldest manmade fiber in the world and is a non-synthetic fiber.

Nowadays, viscose and modal are made from the cellulose of a wide range of different plants. The majority of global viscose and modal fibers are produced from natural feedstock such as eucalyptus, southern pine, acala, birch, beech, aspen and maple as well as other trees or bamboo. Recent research and development (R&D) approaches within the MMCF industry are exploring the use of different natural fibers for MMCF production. However, viscose as the most commonly used MMCF is derived from wood pulp. According to the Rainforest Action Network 150 million trees are logged every year for the manufacturing of manmade fibers. MMCF such as viscose/rayon, lyocell and modal (but also cupro and acetate) from the second most important cellulosic fiber group after cotton, with a demand of between 6 and 7 million tons annually (Fig. 1.1).

Fig. 1.1

Global production of MMCF in 2017 (Textile Exchange 2017)

• Viscose is the most commonly used MMCF and makes up more than 80% of MMCF used in the market.

• Lyocell is a generic fiber made using a different non-toxic solvent. It is produced mostly from eucalyptus tree pulp.

• Modal is a fiber which is produced from beech trees using a slightly modified viscose process.

• Acetate is a fiber derived by reacting purified cellulose from wood pulp with acetic acid and acetic anhydride (the reason for its name) in the presence of other chemicals.

• Cupro is different to the other fibers since it is a regenerated cellulose fiber produced by treating cotton cellulose with cuprammonium salt. Its correct name is cuprammonium rayon due to the associated manufacturing process.

Though there was a drastic decline in the demand for MMCF at the beginning of the twentieth century, because of the development of synthetic fibers, the viscose industry is currently in a healthy state due to its use of new plants sourced from Asia. Actual growth forecasts for viscose are already exceeding those of many other fibers, including polyester staple fibers, expecting to reach an output of 10 million tons in the next 15 years.

From 2015 to 2016, Viscose saw a double-digit growth due to increased production in China. Based on the Preferred Fiber Markets Report 2017 (Textile Exchange 2017), the global production of manmade cellulosic fibers was estimated at 6.7 million metric tons in 2017 with viscose alone making up to 80% of the production volume. MMCFs are produced mostly in Asia (over 80%) (Freitas 2017) with the highest percentage produced in China (over 60%).

2 From Hard Wood to Soft Fiber—The Chemical Transformation Process

In order to understand the transformation from hard wood to soft cellulosic fiber, it is necessary to elaborate on the entire process from the raw material to the final MMCF (Fig. 1.2).

Fig. 1.2

From wood to fiber

For the production of MMCF, such as viscose, modal and lyocell from natural feedstock, use of materials with a high content of α-cellulose is the main criteria.

2.1 Feedstock Assessment—The Pros and Cons of Feedstock Used for the Production of MMCF

Beside the MMCF cupro, which is produced from cotton linter, which is the fine and silky fibers sticking to the seed after the ginning process, the remaining MMCFs, such as viscose/rayon, modal, lyocell and acetate, are produced mainly from wood, with a small percentage from bamboo.

According to the environmental organization CANOPY (Canopy 2018), more than 150 million trees are logged every year and turned into cellulose fabrics. The non-governmental organization claims this logging includes endangered and ancient forests, used for feedstock for MMCF production through its international CanopyStyle campaign. CANOPY is urging international fashion brands to ensure that their purchasing decisions are ethically and environmentally responsible. CANOPY has developed a set of guidelines, the so-called CanopyStyle Audit Guidelines, that verify producers are meeting requirements and are therefore recognized as unlikely to source from endangered and ancient forests. Since the establishment of CANOPY, more than 750 companies globally, including the paper industry, changed their sourcing practices toward more sustainable feedstock.

Besides the change in sourcing policies toward a more responsible and sustainable raw material, MMCF producers globally are intensifying their R&D activities to focus on alternative feedstock for cellulose production. Promising natural fibers with high α-cellulose content and low hemi-cellulose content are found in the fibers of banana leaves, pineapple leaves and abaca leaves, which is a plant similar to the banana plant. Other experiments with straw as feedstock have been carried out. Although these alternative solutions are actually at the laboratory stage and relevant scale ups have to be conducted, the use of alternative fibers could become an interesting option for the production of MMCF.

2.2 The First Step—The Pulping Processes

Prior to the production of MMCF from α-cellulose, it is important to transform wood into so-called pulp, which is a lignocellulosic fibrous material that can be considered a pure cellulosic fiber. The main goal in the pulping process is to separate wood fibers from one another in order to prepare fibers, with the help of chemicals, for further processing. Common processes used in the industry to de-lignify woody material are the KRAFT and SULFITE processes. The major pulping method is the KRAFT process, developed by Dahl in Germany in 1879, whereby late in the process the lignified middle lamella, which is situated between wood fibers, is removed using an alkaline solution and high temperature. Within the KRAFT pulp process most of the chemicals, especially the inorganic chemicals, are recovered and reused. Due to its design, the KRAFT process can accept a wide variety of wood as feedstock (Fig. 1.3). The SULFITE pulping process is used for approximately 10% of the global pulp production.

Fig. 1.3

Simplified overview of the conventional KRAFT pulp process (author’s own graphic)

The basic difference between the pulping processes is the pulping liquor used for dissolving the wood chip feedstock. In the SULFITE process the liquor is produced by stoichiometric burning of sulfur in order to produce sulfurous acid. The cooking liquor is then adjusted by adding hydroxides or carbonates to the watery solution.

Although the yield of the pulp from the SULFITE process is higher compared to the KRAFT process, the cellulose fibers generated by this process are not as strong as the fibers from the KRAFT process, due to hydrolysis. However, the SULFITE process is not as destructive as the KRAFT process, resulting in a better use of process by-products. Typical bio-based products from the SULFITE process are acetic acid, furfural, soda, xylose or wood sugar and sodium sulfate (Sjoestroem 1993). Many of these products are used in the food industry.

2.3 The Production Process of Manmade Cellulosic Fibers or MMCF—Viscose/Rayon, Modal, Lyocell, Acetate and Cupro

This section describes MMCF production processes in more detail. It needs to be mentioned that the modal fiber production process is similar to that of viscose production process, albeit with a few differences. Modal fibers are only produced from beech wood and the regeneration process for cellulose, the part in the process where zink is added, is artificially slowed, resulting in very soft fibers. Therefore, only the viscose production process (Oekotextiles 2012) will be explained in detail (Fig. 1.4).

Fig. 1.4

Simplified viscose process (author’s own source)

3 The Viscose Fiber Manufacturing Process

The pulp from the pulping process is dissolved in caustic soda. The NaOH reats with the cellulose forming Na-cellulose. After the soaking process, the solution is pressed through a filter system to remove excess liquid and the remaining Na-cellulose, as a white crumb, is aged through exposure to the air. This aging process influences the viscosity of viscose and modal. The longer the exposure to air, the lesser will be the viscosity of the Viscose.

Mixing the N-cellulose with carbon disulfide, CS₂, under a controlled temperature produces a honey colored xanthate, with a consistency similar to sodium cellulose, in a process called xanthation. The sodium xanthate is again dissolved in caustic soda, NaOH, for ripening. This process is called regeneration and in the presence of water cellulose is formed from sodium xanthate. The process of decomposing is controlled by adding zinc to the solution.

This process releases carbon disulfide, CS₂, and hydrogen sulfide, H₂S, which are considered to be decomposition by-products. Due to the high toxicity of CS₂ (Lay 2000) and H₂S (National Institute 1997) emissions, it is imperative are recovered using state-of-the-art production technology. Reported recovery rates for CS₂ are from 64% to 97% (Bartsch 2018). According to Lenzing AG, their ECOVERO^™ fibers generate up to 50% less emissions and have a lower water impact compared to generic viscose.

Carbon disulfide is used in large quantities as an industrial chemical for the production of viscose rayon fibers. In this technological process, for every kilogram of viscose produced about 20–30 g of carbon disulfide and 4–6 g of hydrogen sulfide are emitted (National Institute 1997), and if not treated properly are released into the air.

4 The Lyocell Manufacturing Process—A Different Fiber

Due to the use of highly polluting and toxic chemicals in the viscose/modal process toxic effluents were frequently released into the environment. In the 1920s researchers started in the 1920s to set up a different, less toxic, process for the production of fibers (Owens 2013). This was based on the idea of dissolving cellulose directly with chemicals that were easy to use and recover, instead of breaking down the cellulose in wood pulp. In 1939, two Swiss chemists suggested the use of non-toxic amine oxide. Later, the scientist Dee Lynn Johnson filed the first patent for the use of non-toxic N-methylmorpholine N-oxide (NMMO) to directly dissolve cellulose.

Lyocell can be considered a form of viscose produced from bleached eucalyptus and a small amount of beech wood pulp, as the only wood source, derived either through the KRAFT or SULFITE process. Lyocell was finally developed in the United States in the early 1970s and became famous under the name Newcell. Today, the lyocell fiber has found increased use within the fashion industry and is known under the name TENCEL^™ Lyocell from Lenzing AG or Birla Excel^™ from Aditya Birla Group.

Different to the viscose/modal process, cellulose is dissolved in a hot organic solvent, NNMO, in the lyocell process, creating a clear but viscous solution. This viscous solution is filtered and pushed through a spinneret drawing the fibers into the air and giving the fibers their strength. Fibers are then placed into a water-bath containing a dilute solution of NMMO followed by a drying process where any remaining liquid is evaporated, resulting in the final lyocell fibers (Fig. 1.5).

Fig. 1.5

The lyocell process (simplified)

The NMMO solvent used in the process is recycled and reused. Recycling rates differ slightly but a rate of 98% for NNMO is possible using the best available technique (BAT).

5 The Acetate Fiber Production Process

Acetate was first produced in 1923 by the English Company Celanese as part of a wider industry approach designing fibers from cellulose. At the beginning of the 1930s, several companies in the United States started producing acetate making the United States the world leader in Acetate production. Acetate is produced from cellulose derived from wood pulp with acetic acid and acetic anhydride in the presence of sulfuric acid. Through controlled hydrolysis, the sulfate and acetate groups are subsequently removed (Changing Markets 06/2017). Hydroglucose is the repeating structure in cellulose, having three hydroxyl groups which can react in order to form an acetate ester. The most common cellulose acetate fiber has an acetate group on every three hydroxyl groups and is known as diacetate or simply “acetate fiber.” Such fibers have an esterification degree of between 2.22 and 2.76. When the three hydroxyl groups form an acetate ester, the fiber is called triacetate with an esterification degree of between 2.76 and 3.0.

After the diacetate or the triacetate is formed, the fibers are dissolved in acetone. In the extrusion process, the solvent evaporates creating acetate fibers (Fig. 1.6). Acetate fibers represent the second highest share of MMCF but are most often used for non-textile applications. For fashion and textiles, the branded acetate fiber Naia, from Eastman Chemicals, is gaining attention through its application of integrated chemical management and a life cycle assessment (LCA) that has been third-party reviewed by Quantis International.

Fig. 1.6

The acetate production process (own chart)

6 Cupro Fiber Production—The Bemberg Process

Within the search for artificial silk at the end of the nineteenth century, a scientist named Schweizer discovered that cellulose dissolves in a solution of copper and ammonia, forming so-called cuproammonium, Cu [(NH₃)₄] (OH)_2. Basically, cupro can be considered a type of viscose produced using a completely different technology, the so-called Bemberg process. It is the first ever fiber production process using regenerated cellulose. Today, the only remaining global cupro producer is a company called Asahi Kasei. They successfully implemented the Bemberg process within their production in 1931.

Today, cupro is made using cotton linter which are the short and downy fibers attached to cotton seeds after the grinning process. Cotton linter is soaked in a bath of caustic soda, NaOH, steamed and bleached. The cellulose is then dissolved in a mixture of copper hydroxide and ammonium hydroxide, Cu [(NH₃)₄] (OH)_2. The clear polymer solution is then filtered using a slightly alkaline bath and undergoes an aging and de-aerating procedure. Coagulated cuproammonium fibers are washed in a 5% sulfuric acid solution. The fibers are then ready for spinning into staple and filament yarn (Fig. 1.7). The main advantages of the Bemberg cupro process over the viscose process are the use of a cellulose pulp with a lower degree of polymerization, Degree of Polymerization (DP), content. In addition, since cupro is made using cotton fibers it can be dyed using reactive dyestuff.

Fig. 1.7

Manufacturing process for cuprammonium rayon (cupro) (author’s own diagram)

The main disadvantage of the cuproammonium process is the toxicity of the copper sulfate, requiring the full recovery of copper salts used. It is imperative that waste water treatment removes any copper compounds, thereby observing national waste water standards. This requirement limits the large-scale production of cupro.

7 Environmental Impact—MMCF in the Spotlight

A recent LCA for the brand Stella McCartney, conducted by SCS Global Services, evaluated the impact profile of ten different MMCF production variations derived from five completely different natural feedstocks (wood from different forest regions, bamboo pulp, cotton linter, flax by-products, recycled clothing), with supply chains across four continents. This published LCA was the first of its kind to assess the global MMCF sourcing scenarios where terrestrial and freshwater ecosystems from specific forests of origin were included. The study was completed in October 2017 and was made available to the public online. It showed that all current commercial viscose production systems carry very different but serious risks.

Recent campaigns by the environmental organization CANOPY (Canopy 2018), considering unsustainable feedstock for MMCF production in terms of endangered trees and forests, and the Changing Markets Foundation, an environmental organization working in partnership with NGOs (Changing Markets 06/2017) with a focus on global environmental pollution and harm to human health through the production of MMCF, have raised global awareness of MMCF production in general. With its critical reports on the global textile industry and especially the viscose industry (Changing Markets 06/2017, 12/2017, 02/2018, 07/2018, 11/2018), Changing Markets has requested brands work with their viscose suppliers in order to establish a responsible and sustainable chain of production to protecting the environment and human health. Based on the research of Changing Markets, global viscose production is causing tremendous damage to the environment through water, soil and air pollution associated with the toxic chemical carbon disulfide and its by-products formed during the viscose process.

The Changing Markets reports created momentum toward increasing awareness not only globally at the buyers end but also within other organizations such as the association known as the Zero Discharge of Harmful Chemicals and the Stichting ZDHC Foundation, with its Roadmap to Zero Program. Within the Roadmap to Zero Program (ZDHC 2018), the ZDHC take a more holistic approach when tackling problems related to hazardous chemicals in the global textile, leather and footwear supply chain through the Manufacturing Restricted Substances List, MRSL.

The ZDHC established a MMCF working group in 2018 where, alongside its signatory member brands and the global MMCF industry, it is working on a unified standard and roadmap for the discharge of hazardous substances into water and the air, as well as solid waste products like sludge.

Another call to action from the supply side of the industry is the Chinese initiative CV, the Collaboration for Sustainable Development of Viscose. CV is a collaboration of ten major viscose fiber producers—collectively representing over 50% of the world’s viscose staple fiber production—in partnership with two trade associations. This self-regulating initiative aims to see its members adopt a recently launched roadmap focusing on available standards and programs, increased transparency and continuous improvement toward a best available technique (BAT) (CV 2018).

8 The Characteristics of Different MMCF Fibers

MMCF has many competitive advantages: viscose has many great characteristics including its versatility, high level of absorption, smoothness, strength, color retention, breathability, lightness and low cost (Ramos 2018). MMCF combines the comfort of natural fibers with the advantages of synthetic fibers, such as purity and consistent quality. Thus, MMCFs are strategically positioned between natural and chemical synthetic fibers. The most important fact relating to the excellent physiological properties of cellulose fibers is their reversible absorption of moisture, which is different to synthetic fibers like polyester where moisture condenses on the surface of the fabric producing a film. Due to its physical properties, MMCFs such as viscose, modal and lyocell can be blended with almost all natural and synthetic fibers such as cotton, linen, silk, wool, polyester and polyacrylic. The major applications of MMCF include yarns and sewing and embroidery threads, fabrics and apparel including linings, domestic textiles of any kind, industrial textiles for medical applications, as reinforcement materials used in rubber tires and belts and as a major feedstock in the production of carbon fiber. In this chapter we focus on apparel, where MMCF has gained momentum in the industry because it is considered a skin-friendly and environmentally friendly option—advantages that are expected to drive market growth for the years to come. In addition, MMCF will continue to be used to replacing other fibers in the commercial landscape, such as more expensive and less easy-to-care-for silk, especially in women’s wear and lingerie, and synthetics. MMCF claims to be biodegradable and renewable offering a cotton-like feels. This represents a significant advantage for MMCF in the future since rising demand of cellulose based fibers cannot be met by cotton due to price and availability (Table 1.1).

Table 1.1 Main characteristics of MMCF (author’s own illustration)

As the industry is investing at a fast pace and output is increasing, there has been an expansion in applications due to increased varieties of fiber finishes and blends. In particular, blends with synthetic fibers have flooded the retail space—being attractive from a price and comfort perspective—thus further fueling demand.

Especially complex blends, used for inexpensive fast fashion items, are expected to pose a significant challenge in terms of waste and recycling.

The vast amount of viscose available on the current international market, produced relatively cheaply using processes described earlier, are having a devastating impact on workers, local communities and the environment. This is why conventional viscose (including bamboo viscose) was given “D” and “E” scores for sustainability in the Made-By Environmental Benchmark for Fibers.

9 Recent Innovations for a More Safe and Sustainable Production of MMCF

There is no question that the production of fibers in the future needs to have a reduced social and environmental impact, challenging the industry to adopt a more sustainable sourcing procedure in terms of the feedstock used for the MMCF production as well as the production process itself. Interesting alternatives for a more sustainable feedstock through the use of different fibers, and also pre- and post-consumer cotton products, are already available and in use. Such options might not be able to totally replace the existing feedstock but could serve as a promising substitute.

In terms of the production process new cellulose dissolving techniques are needed that replace the currently used toxic chemicals. But the most important steps are to ensure that the chemical production process is being carried out in in a “closed-loop” process ensuring the highest recovery rates for the chemicals used.

9.1 Feedstock Alternatives and Recycling Options

Non-wood-based cellulose input can be derived from alternative feedstock plants such as flax or algae, plant residues considered as agricultural waste like straw, or leaves and by-products from the food industry like citrus peel or fruit skins. Obviously, textile waste with high cellulose content, mainly from cotton, can also be used as an alternative feedstock for MMCF production: recycling of post-production (e.g., cotton scraps in the cutting room), pre-consumer (e.g., samples or stock that cannot be sold) or post-consumer (disposed textiles after being used) textiles is increasing but still faces many barriers to scalability (Fig. 1.8). Barriers include for example impurities and possible contamination with residues from wet-processing or the use phase. There are costs associated with identifying and resolving such issues, presenting a new financial barrier. For example, it requires an expensive chemical processes to prepare dyed textile feedstock for the dissolving process.

Fig. 1.8

Alternative cellulose feedstock examples (different sources 2018)

9.2 The Use of Textiles as Feedstock for MMCF Production

Cellulosic waste is generated throughout the textile supply chain. Spinning, weaving and knitting, as well as other cotton and MMCF manufacturing processes, generates waste, 25% of which can be mechanically and chemically recycled. Recycled textile feedstock has various advantages including the mitigation of impacts of any virgin feedstock. Furthermore it supports the principles of the Circular Economy through recycling of textile excess and regional manufacturing opportunities.

A mechanical process that re-spins or just tears material into shorter fibers would not be classified as an MMCF process. The chemical recycling process of cellulose content into MMCF includes a dissolving process and can offer many opportunities no matter whether completed post-production, pre-consumer or post-consumer, as long as a very high cotton content, typically around 90%, is used.

The first commercially available lyocell fiber, containing recycled cotton, was launched by Lenzing AG in 2017 and more and more of their Refibra™ branded products are making their way to the marketplace (Lenzing 2018).

Fashion Positive (Fashion+) has identified viscose as a desirable material with high economic potential. Fashion Positive considers chemically recycled cellulose from post-consumer waste a new and innovative material. Their goal is to:

• reduce the use of raw materials sourced from natural feedstock,

• divert waste from landfill, and

• use safer chemistry.

In addition, they want to implement different chemical recycling technologies for apparel made from cellulose fibers in order to generate new virgin-quality viscose fibers that meet the requirements for C2C gold or platinum certified products (Fashion Positive 2018).

Within the recycling process of re:newcell™, cotton and other natural fibers are dissolved into a new, biodegradable, raw material called re:newcell™ pulp. It can be transformed into textile fibers and introduced into the textile production cycle, meeting all industry requirements (Re:newcell™ 2018).

New technologies have recently started to chemically recycle fiber blends containing polyester and cotton. To ensure full fiber–fiber recycling, cotton and polyester have to be separated chemically. One example from Mistra Future Fashion is the Blend Re:wind process, which has been developed using existing industrial processes and aims to reduce waste as much as possible in order to minimize both environmental and economic costs, while boosting business. A scaling up to industrial production is the biggest challenge since processes are very costly (Tecycling Magazine 2017).

Other innovators in textile recycling and MMCF production techniques include, but are not limited to, Evrnu, Worn Again, Saxcell, HKrita, Tyton BioSciences and the Infinited Fiber Company. Other promising results from R&D at universities include WSU’s Department of Apparel, Merchandising, Design and Textiles in Washington DC.

9.3 Cotton Linter as Feedstock

Cotton linter, also referred to as “cotton wool” in the United Kingdom, is formed from the short fibers remaining on the seed after ginning. It is used for spinning (first cut) or pulp production (second and third cut) as well as for medical, cosmetic and many other practical uses (Balajicottonlinter 2012). Cotton linter pulp is used for paper and for the cupro production process as the sole feedstock, as mentioned earlier in the chapter. Cupro fibers are exclusively produced by one supplier, Asahi Kasei from Japan, under the trademark “Bemberg”. An Innovhub third party laboratory test recently proved (Knitting Industry 2017) that cupro fibers are fully biodegradable, and as such can be used to produce caskets for end of life option. Cupro is also GRS certified (Global Recycled Standard) and Asahi Kasei commissioned an LCA study prepared by Istituto per la Certificazione Etica, ICEA, Italy.

9.4 Other Alternative Feedstock

Alternative feedstock plays a marginal role in MMCF production today. Although many laboratory innovations are available and are being tested by international brands or are gaining attention through scaling programs, supported by grants from industry and governments, quality issues, feedstock collection logistics and purity, cost competition and questions around impact still persist.

One example of using agricultural waste for acetate fiber production is the use of orange fiber from orange peel. Table 1.2 shows cellulose, hemicellulose and lignin content found in alternative feedstocks.

Table 1.2 Cellulose, hemicellulose and lignin content (Textile Exchange 2017)

Other early stage innovators include: Agraloop, a company using various types of agricultural waste; Mestic, focusing on cow manure as a feedstock; BJMC, working with jute; and Aalto University considering algae.

Each feedstock presents its own advantages and challenges.

9.5 Processing Technology Alternatives

Next to certification of an integrated (often referred to as “closed-loop”) process or using a non-toxic solvent as explained in the section about Lyocell, the industry is still lacking alternatives to convert feedstock into a MMCF. More than 90% of MMCF is still produced with all the environmental and social risks discussed earlier in the chapter.

Innovative, yet early stage, alternatives to dissolving cellulose include the utilization of an ionic liquid, for example, Ioncell-F.

“Cellulose is a supermaterial of the future,” according to the VTT Technical Research Center of Finland, Aalto University, Tampere University of Technology and the University of Vaasa. Researchers are collaborating to develop new biomaterial applications as part of the Design-Driven Value Chains in the World of Cellulose (DWoC), seeking new design-driven applications for cellulose and developing related technology as well as exploring new ways to create value in cellulose-based ecosystems. These new materials and innovations can replace traditionally used raw materials in textile products, interior decoration elements and car interior materials (VTT 2015).

Crailar FTI has invented enzymatic processing of flax fibers, drastically reducing the use of chemicals and water. The Crailar process transforms bast fibers into soft and fluffy fiber, composed of thousands of individual bast fibers, resembling the feel and appearance of cotton (Bastfibretech 2019).

Nanollose is a biotechnology start-up which has developed a process using a non-hazardous and non-infectious bacterium that converts biomass waste from beer, wine and other liquids into microbial nanocellulose fibers, thus creating a “plant-free” cellulose, branded “Nullarbor.”

Another alternative to the traditional dissolving process has been introduced by Spinnova. In this process defibrillated cellulose goes through mechanical spinning. Spinnova represents a disruptive, ecological innovation that turns cellulose into textile fiber simply, without harmful chemicals. Currently, the fiber is still in the R&D phase, being developed together with respective brands to suit demand from commercial products (Spinnova 2018).

10 Conclusions and Outlook for Manmade Cellulosic Fiber

While conventionally produced MMCF currently aims to use sustainably sourced wood pulp feedstock and ensure integrated processing technologies, in the future we do not want arable land transformed into monocultures of fast-growing trees.

We need to look at alternative feedstocks that do not compete for land, we need non-toxic, integrated production of pulp and fiber, and we have to continuously try to replace virgin inputs. Recycling cotton products could theoretically replace all virgin feedstock.

There are many promising innovations and start-ups that have introduced their products to the industry. Most are still at a very early stage and need a set of strong partners to scale up production. We expect governments, industry initiatives and companies investing and testing, as well as supporting, for example, “Fashion For Good,” a platform for sustainable innovation based in Amsterdam, to accelerate the adoption of new, safer technologies that represent the work of over a hundred young innovative companies (Safermade 2018).

Currently, it is imperative to generate a clear picture of industry, identifying the big issues and impacts and how innovation and new technologies can address such issues successfully. This picture will give an indication of potential, will allow comparison and also help innovators attract investment capital. Action is required from a broad group of actors, both within and outside the industry, such as brands, retailers, suppliers and R&D as well as investors, governments and the cummunity advocacy. We believe the conventional MMCF industry must not continue producing low-cost MMCF at the detriment of the people and planet.