THERE WAS A time, in the not-too-distant past, when the question of textile sustainability centred on water and oil, natural and synthetic. Essentially natural fibres were generally regarded as good, coming from renewable resources and capable of being recycled. Synthetics on the other hand have been seen as largely derived from oil, not a quickly renewable resource and more problematic to recycle. This viewpoint is changing and one of the main reasons is undoubtedly water. Over the last 60 years the world’s population has grown from around 2.5 billion to almost seven billion. The net result of this is that irrigated land for farming purposes has doubled while water drawn has tripled. Water usage varies sharply depending on the climate, soil and the crops being grown. British farmers use just three per cent of water withdrawals, while Indian farmers rely on irrigation for almost 90 per cent of their needs. Population growth and its incumbent demand for more food and clothing have certainly impacted on farming.
However, much of the problem can be traced to environmental mismanagement at a national and international level. In reference to the impact of cotton on the Aral Sea, the World Bank states it bluntly: ‘Under the Soviet system, economic growth was pursued in blatant disregard to natural conditions’. In this well-documented environmental disaster, the problem can be traced back to a deliberate decision to divert the rivers needed for irrigation away from the Aral Sea to the desert in order to produce cotton, rice and fruit. Today, Uzbekistan is one of the largest exporters of cotton. Quite an achievement for a country unsuited to growing the crop.
Oil forms the basis for many of the man-made textiles currently in use. Concerns about their environmental impact has led to a re-evaluation of all aspects of the industry, from yarn production, textile coatings and finishes through to product design, use, reuse and disposal. Water usage is one area where synthetics find that they can offer an advantage over natural fibres, particularly during the product’s lifespan. With an increasing trend towards the use of metered water, not just in industrial but also in domestic use, consumers are becoming more aware of how much they use and the thirstiest domestic appliances. Laundry consumes almost as much as showers and baths and is one area where regulation is being applied. One of the benefits of synthetic over natural fibres is lower water and energy usage during the laundry process. The frequency of laundry is also being considered, particularly with the advent of new coating and finishing treatments for synthetic materials.
While neither natural nor man-made fabrics are proving to be perfect, both have positive attributes to offer in the search for more sustainable materials. The question that material scientists and designers are now asking is whether these strengths can be developed into new, possibly-hybrid materials. Can the future be a synergy of natural and man-made, nature and nurture?
Nature
Natural fibres are generally divided into two categories - those derived from plants such as cotton and hemp, and those derived from animals that include wool and silk. Cotton, wool, silk and linen have long dominated the market for natural fibres. More recently, a new group of natural fibres has been launched on the market that includes wood and bamboo. These offer new aesthetics and performance characteristics and are being used in industries ranging from clothing to composites, a process where two or more materials are combined to produce a third, new material with enhanced performance characteristics. Many of these materials have been used for some time in traditional textiles. However, the development of advanced processing technologies is making it possible to produce them commercially. There is no longer a widespread assumption that because a material is natural it is going to be environmentally friendly. Natural fibres must now prove their environmental credentials in just the same way as their man-made counterparts.
Cotton
In considering the sustainability of any fibre, production is just one part of the story. In the case of cotton it is a big part, but laundry care during its lifetime is also a major issue. The Cotton Incorporated Lifestyle Monitor has found in its survey that more than 60 per cent of women prefer to wear cotton trousers that are wrinkle resistant. The original non-iron cotton using a cross-linked resin finish was developed in 1969 by Dr Ruth Rogan Benerito, a scientist at the US Department of Agriculture. The initial results, though effective, left the fabric with a harsh handle and did not prove popular (Benerito, undated). The technology has become much more refined to the point where leading retailers such as Brooks Brothers can estimate that 70-80 per cent of their sales in women’s woven shirts are in non-iron cotton.
Lyocell
The Lenzing Group was presented with a Vienna Stock Exchange Award 2010 for its work on sustainable textiles. One of the company’s leading brands is Lyocell, a cellulose fibre made from wood pulp and marketed under the trade name Tencel. The wood pulp is converted into nanofibrils using nanotechnology so that the result is an exceptionally fine yarn that offers high moisture management with good tactile properties. Tencel absorbs excess liquid then quickly releases it into the atmosphere, helping to keep the body at a comfortable temperature. This function carries an additional anti-bacterial benefit: because excess water is moved away from the skin bacteria have less opportunity to grow. The smooth surface of the yarn makes it pleasant to wear and gives the cloth a good handle and drape.
Smartfibre AG produces a lyocell fibre with enhanced health properties. SeaCell sees the lyocell fibre incorporate seaweed as an active ingredient. Seaweed has long been used in Chinese medicine and is recognised as offering protection for the skin and containing anti-inflammatory properties. There is termed an ‘active exchange’ between the fibre and the skin. The company describes how there is a movement of substances between fibre and skin with nutrients such as calcium, magnesium and vitamin E released by the body’s natural moisture when a garment using the fibre is being worn.
Hemp
Although its use in textiles can be traced back to 8000 BC it is marijuana’s association with hallucinogenic drugs that brought it to public attention in recent times. This is now changing as it has been shown that the plant used for fibres has less than one per cent of Tetrahydrocannabinol (THC), the active chemical in cannabis. This is far too little to be used as a recreational drug. The plant has the benefit of growing quickly, yielding more fibre per acre than any other crop. It renews the soil rather than draining it of its nutrients, can be grown without chemical spraying for pest control and is biodegradable.
Bamboo
Opinion is sharply divided as to whether bamboo is sustainable or not. The issue revolves around water. The fast growing plant can reach its full height in about three months, spreads easily with little intervention, pesticides, fertilisers or water needed to grow. It is biodegradable, naturally antimicrobial, thermodynamic and protects against ultraviolet (UV) rays. The issue begins with the processing and subsequent labelling of bamboo. One method is similar to that used in hemp and involves mechanical crushing to extract the fibres, with natural enzymes helping to further break them down. In the second, fibres are chemically broken down using lye, carbon disulphide and strong acids, then extruded through mechanical spinnerets. A further product, bamboo charcoal, is a rayon bamboo fibre whereby the carbon from burnt bamboo is microencapsulated within the fibre to enhance the antimicrobial properties. The first method of production is a natural bamboo fibre, while the second is bamboo rayon with a world of difference from an environmental point of view. There is a call for the labelling of rayon derived from bamboo to say just that, rather than generic bamboo. The Competition Bureau of Canada has taken a stance on the matter and in January 2010 announced that 450,000 textile articles were being relabelled and over 250 website pages corrected. That is a staggering figure for a country with a population of just 33 million, half that of the UK.
‘Techno-naturals’
There is a growing move to apply technological advances to nature to produce what are in effect techno-naturals. Du Pont’s Applied Science Division has developed a way of turning cornstarch into fibres. Sorona is made from starch extracted from the kernel of the corn and the company is also looking at ways of extracting starch from the stalk and other parts of the plant. The starch is put through a fermentation process where glucose is fed down pipes into a three-storey vat that contains genetically engineered organisms, water, vitamins and minerals. The resulting monomer is polymerized with a petroleum-based polymer and cut into pellet form that is converted into fibres. A key reason given by Du Pont for the growing interest in this area is the increasing cost of petroleum that had previously been less expensive than sugar.
The creators of Agent Orange and at the forefront of genetically modified (GM) seeds, Monsanto is no stranger to controversy. The company was the first to introduce GM cotton under the brand name Ingard in 1996, followed more recently by Bollgard II, with the promise that it would reduce the use of pesticides by 80 per cent compared with conventional crops. This in turn, it argues, cuts down on contamination of the waterways. Monsanto is currently developing new water use efficiency and nitrogen use efficiency traits aimed at further conservation of water and nitrogen.
Nurture
Dialogue between regulators, designers and manufacturers is resulting in much more than new fibre and fabric developments. What we are seeing is the emergence of new systems for design, manufacturing and consuming. These initiatives are not only more sustainable, but are producing some of the most exciting new developments to come from the textile industry in recent years.
Polyester
The Japanese textile manufacturer Teijin has taken the innovative step of involving the consumer directly in the production of its polyester PET fibres. Ecocircle is a closed-loop recycling system that takes polyester products at the end of their use and turns them into polyester PET fibres at its Matsuyama plant. The company encourages consumers not only to buy products with the Ecocircle label, but also to bring them to a recycling bin at a participating store or post them to Teijin direct. Its website includes information in the form of an animation that encourages the consumer to engage with the idea that synthetic products can evoke their own sense of empathy and through the recycling process we may end up wearing that favourite soft toy we have outgrown as a shirt. A sense of engagement comes more readily with natural materials that people are more inclined to keep for longer, repairing and valuing much of the wear and patination that occurs. The Teijin message is an important one in getting users to think again about how they engage with and ultimately dispose of products that use man-made materials.
Teijin has developed a number of fibres using the process, including Microft, Welkey and Cortico. All are high performance health-giving fibres that build on the company’s expertise in highly engineered fibres. Microft is a soft handle, high-density microfibre with a water repellent finish used in sports and leisurewear. Welkey is a hollow fibre specially designed to wick perspiration away from the body. Cortico is also intended for moisture control and uses a highly engineered triangular fibre containing small apertures on the surface to absorb perspiration more readily.
New manufacturing technologies
The process of laser sintering, or 3D printing as it is sometimes known, is where lasers are used to fuse fine particles of nylon, plastic or metal to form strong three-dimensional objects. The benefit of the process is that whatever excess powder remains after the sintering can be reused so that there is zero waste. Generally regarded as an industrial design and prototyping process, the Dutch designers Freedom of Creation have explored the possibilities of the process in their textile-based work for fashion and accessories. While solid forms can take many hours to produce, the Freedom of Creation designs are not unlike modern day chain mail, intricately linked patterns but extremely lightweight. The garments and bags are seamless and can be of a mono-material. A further benefit is that small production runs are possible, reducing the risk of unsold stock building up in warehouses or being wilfully destroyed as H&M were accused of doing in New York City in an article by New York Times journalist Jim Dwyer.
Nanotechnology is manufacturing at a molecular level, smaller than 100 nanometres (nm) or 100 millionth of a millimetre. In essence this is the building of structures, including materials and coatings, atom by atom. The technology is at a relatively young stage of development, although products are being launched in a number of areas including coatings for textiles.
The leading Swiss performance fabric manufacturer Schoeller was one of the first to bring a nanocoated textile to the market with its nanosphere coating. This is an ultra-fine water repellent coating whose engineering was inspired by the lotus leaf, which has a bumpy surface texture and wax-like finish to repel water, taking dust and dirt with it. The impact of the coating of textiles is referred to by the company as the ‘self-cleaning effect’. Water and dirt are repelled, as is oil. Because of this function, nanosphere coated fabrics required less frequent and lower temperature washing.
However, it is the next stage of nanotechnology where things promise to get really exciting and we see the production of high strength carbon nanotubes. Nanotubes, as the name suggest, are a tube-shaped material made from carbon atoms bound together to create a stiff structure that forms the strongest existing carbon bond. They are categorised by their structure, which can be single-walled, multi-walled or double-walled. Initial progress has been good, but scale and the cost of production still has to be overcome in order to make it a viable manufacturing process.
Hybrid
Hybrid materials see the bringing together of two or more different materials to make a new one with enhanced performance characteristics. In a fabric context, the term is usually used to refer to combinations of natural and synthetic or textile and non-textile. The benefit from a sustainable point of view is the temperature and frequency of washing that these new hybrids allow for, as well as their extended lifecycle. The negative is that they are not by their very nature monomaterials and with high performance elements often including hard to recycle metals or liquid crystal polymers (LCP) these are not in themselves ideal from a sustainable point of view. The aim in developing these materials is to combine the best of both worlds with some interesting results, aesthetically, in terms of performance and environmentally.
In Switzerland, for example, the Scholler Spinning Group has developed a hybrid wool and stainless steel yarn for use in anti-static clothing. In the yarn, the Merino wool is randomly interspersed with less than 10 per cent Inox stainless steel fibre. The resulting yarn can be easily dyed, knitted and finished with treatments such as dirt repelling Teflon without interference with the shielding performance. The ability to combine capabilities such as these in a single yarn is relatively new. Less than a decade ago this would not have been possible without reducing, or even destroying the performance of one or both functionalities.
Conclusion
Natural, man-made and hybrid combinations of fibres are making a concerted effort to improve their environmental impact. The scale of the problem is such that individually none of these developments will make the changes necessary to achieve a real difference. What is needed is to see these developments coupled with individual and collective responsibility and action.
Extract from ‘Shaping Sustainable Fashion: Changing the Way We Make and Use Clothes’, edited by Alison Gwilt and Timo Rissanen, 2011.