Friday, March 16, 2012

What’s in a Fibre?

What’s in a Fibre?

Modern textile fibres fit into one of two main categories of fibre forming polymers; natural and synthetic/manufactured. Natural polymers exist as short fibres from either a vegetable source (cotton and linen) or animal source (sheep wool or animal hair fibres). Regenerated fibres are produced from cellulose in wood pulp which is dissolved in chemicals and formed into filaments. Viscose and modal are examples of regenerated fibres. Finally, synthetic polymers such as acrylic and polyester are manufactured, usually produced from petrochemicals by a process called polymerisation. A fibre is a fine and flexible textile raw material which will usually be spun into a yarn, which in turn can be used to make fabric. Fabrics can be woven, knitted, felted or bonded.

Natural Fibres

Natural fibres are the oldest type of fibres used by humans because they appear naturally in the environment in their raw form. Natural fibres should be sustainable because they are renewable, i.e. they come from sources which can be replaced regularly – plants which can be seeded and animals which can be bred, and being organic, can be broken down and decompose. Wool is arguably the most ancient fibre, as it has long been available from sheep. Wool is composed of the protein keratin and is a relatively coarse fibre, although certain breeds such as Merino do produce a soft, smooth fibre. Cotton is the most commonly used natural fibre and world demand for cotton is growing as the world population grows.

Other fibres have been suggested as more sustainable substitutes for cotton because cotton is quite difficult to grow. Such fibres are hemp, bamboo and even nettle. Hemp can be grown without pesticides as its natural oils do not appeal to pests, however the fabric it produces can be stiff and coarse. Bamboo has been hailed as the most sustainable textile material because it is naturally pest resistant, fast growing, and can help rebuild eroded soil. However, in China where it has become a lucrative cash crop, farmers are clearing natural forest land and using chemical fertilisers to boost yields further, thus showing that the strain of consumption threatens the environmental virtues of bamboo as an alternative fibre.

Regenerated and Synthetic Fibres

The first engineered fibres were produced from wood pulp in the late nineteenth century to mimic the qualities of natural yarns, these fibres are known as regenerated. To make viscose, one of the most popular regenerated fibres, cellulose is extracted from eucalyptus, pine or beech wood chips before entering a complicated chemical processing cycle. The desire to improve on naturally occurring fibres and be able to produce them in unlimited quantities led to the manufacture of artificial fibres in the 1800s.

Synthetic fibres are produced from oil, a non-renewable resource, and as oil prices are rising, synthetics are becoming more expensive to produce, therefore there is a need for sustainable alternatives. Du Pont and ICI developed the first synthetic fibres and became household names. Du Pont’s Nylon fibre (polyamide) became widely used during the Second World War as an alternative for silk in the production of parachutes and military supplies. The physical strength of nylon and its easy availability made it a welcome alternative to expensive natural silk. At the start of the war, cotton accounted for around 80% of fibres used, with wool predominately making up the whole, however, by August 1945, manufactured fibres had a share of 25% and cotton had dropped in usage.

Polyester is now the most popular synthetic fibre, with eleven million tonnes produced each year. It is often blended with natural fibres but in its pure form it is recyclable, although the considerable energy and chemicals required for its manufacture limits its environmental attributes significantly. Since the first synthetic fibres, manufacture has become more sophisticated and the invention of the likes of microfibres and elastane provide high performance properties that natural fibres cannot match.

Emma Waight is a geography researcher and freelance fashion writer for Follow Clothes for advice on clothing shops and fashion news.