Fibre from stinging nettles - Institute for Manufacturing · rials (see papercrete project) can be...
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Where do nettle fibres fit in? Bast Fibres Processing Route Processing Route How can nettles be sustainable? The above diagram shows one way of classifying fibres. At the top level, fibres can be extracted from natural sources, or they can be syn- thesised. Natural fibres tend to have an ecological advantage as they are renewable and biodegradable. Synthetic fibres often have a petro- chemical origin, and can require significant energy to manufacture (pel- lets of Nylon 6 take just over 80 MJ/kg to produce). Nevertheless it is possible to have sustainable synthetic fabrics (and unsustainable natu- ral fabrics), especially if fibre products are synthesised with end of life in mind, such as BASF’s Savant 1 carpet - 99% of which can be recycled. 1 http://www.mcdonough.com/writings/promise_nylon.htm Aims of the project 1. Research into traditional methods of nettle use & processing. Although there has been a recent resurgence of research into nettles (for example the STING project at De Montfort University), nettles have been used for thousands of years. They have many other uses besides fibre, and are known for their medicinal properties. Ideally, it will be possible to find uses for the whole plant, in keeping with zero-waste objectives of sustainability. Investigation into traditional uses should reveal some interesting possibilities. 2. Lifecycle Analysis Are nettles really a sustainable crop? A lifecycle analysis of all the stages, from growing to final disposal, done with respect to water and energy use, should show how fibres from nettle compare to other fibre sources. 3. Identification of barriers to nettle fibre production. Production of fibre from nettles is still insignificant compared to other natural fibres. There are few places that process it commercially, and there is no specially designed equipment. Why is this, and what can be done to increase its use? 4. Profiling/ Mechanical Testing A series of tests to profile the fibre from nettle should identify how nettle fibre is best used. Mechanical properties are perhaps the most important - and can have unexpect- ed effects: a higher Young’s Modulus creates a fabric that is stiffer and can feel “prickly” on the skin. Other properties are important too: Camira Fabrics 3 have discovered that a blend of nettle and wool has very good fire resistance. 3 http://www.camirafabrics.com/content/pages/news.asp?newspage=1&Index=640 5. Investigation into alternative plants (and alternative uses). Nettles are just one of a large number of alternative sources of fibre. Are there other suitable sources of fibre that remain untapped? In addition, natural fibres have a range of potential uses besides fabric. Building mate- rials (see papercrete project) can be enhanced with natural fibres, and there are excit- ing possibilities for reinforcing plastics with natural fibres. J. Gordon Cook, 1968 Processing bast fibres follows a route similar to the one shown above. There are some terms here that need defining: Retting This is a controlled rotting to remove gummy (pectinous) substances which glue fibres to- gether, which can be carried out in a number of ways: water retting - stalks are left in water, and are acted upon by bacteria dew retting - stalks are left out in the field for 6 weeks, and are acted upon by fungi chemical retting - stalks are placed in chemical solutions Currently dew retting is the dominant method; chemical methods tend to damage the fibres. Breaking, Scutching and Hackling Following retting, a sequence of processes to remove the fibres from the woody stalks is car- ried out (first breaking them, then scraping - or scutching - them off ). Hackling is a combing process to separate long from short fibres and to remove the remaining woody material. 1. Nettles could be used in integrated farming The integrated farming system developed by George Chan 2 is a system designed to have zero waste. Elements include livestock, crops and fish. One of its principle components is the biodigester, which takes livestock waste and produces biogas and fertilizer. One of the “paradoxes” of the Integrated Farming System is that it produces an excess of fertilizer. Excess fertilizer can be potentially damaging to an ecosystem through eutrophication (excessive plant growth in water supplies leading to de- pletion of dissolved oxygen). Nettles would be ideal crops to absorb this fertilizer as they thrive in over-fertilized areas. 2 http://www.scizerinm.org/chanarticle.html 2. Nettles have potential to save water Nettle fibres can be as fine as cotton, and they are far finer than flax. However, 7000 - 29, 000 litres of water are used per kg of cotton produced (Soth, 1999). This im- mense water usage can have severe knock on environmental effects. Substitution of nettle fibre for cotton could save large amounts of water. Nettle, flax and wool fibres (from left to right) Cross section of a nettle stem. The fibre bundles are just visible in the dark patches. The stem is hollow, unlike flax and many other bast fibres Cross section of a flax stem, Institut Technique de Lin, Paris Learning to spin Fibre from stinging nettles Bast fibres are found in the stems of plants. These two microscope photos below show cross sections of flax and nettle. The fibres are found in bundles just inside the outer bark of the plant. Other bast fibres include ramie, kenaf and jute. Dr Claire Y Barlow 1 , Daniel Neal 1 1 Cambridge University, Department of Engineering, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
Transcript of Fibre from stinging nettles - Institute for Manufacturing · rials (see papercrete project) can be...
Where do nettle fi bres fi t in?
Bast Fibres
Processing RouteProcessing Route
How can nettles be sustainable?
The above diagram shows one way of classifying fi bres. At the top level, fi bres can be extracted from natural sources, or they can be syn-thesised. Natural fi bres tend to have an ecological advantage as they are renewable and biodegradable. Synthetic fi bres often have a petro-chemical origin, and can require signifi cant energy to manufacture (pel-lets of Nylon 6 take just over 80 MJ/kg to produce). Nevertheless it is possible to have sustainable synthetic fabrics (and unsustainable natu-ral fabrics), especially if fi bre products are synthesised with end of life in mind, such as BASF’s Savant1 carpet - 99% of which can be recycled. 1http://www.mcdonough.com/writings/promise_nylon.htm
Aims of the project1. Research into traditional methods of nettle use & processing.
Although there has been a recent resurgence of research into nettles (for example the STING project at De Montfort University), nettles have been used for thousands of years. They have many other uses besides fi bre, and are known for their medicinal properties. Ideally, it will be possible to fi nd uses for the whole plant, in keeping with zero-waste objectives of sustainability. Investigation into traditional uses should reveal some interesting possibilities.
2. Lifecycle Analysis
Are nettles really a sustainable crop? A lifecycle analysis of all the stages, from growing to fi nal disposal, done with respect to water and energy use, should show how fi bres from nettle compare to other fi bre sources.
3. Identifi cation of barriers to nettle fi bre production.
Production of fi bre from nettles is still insignifi cant compared to other natural fi bres. There are few places that process it commercially, and there is no specially designed equipment. Why is this, and what can be done to increase its use?
4. Profi ling/ Mechanical Testing
A series of tests to profi le the fi bre from nettle should identify how nettle fi bre is best used. Mechanical properties are perhaps the most important - and can have unexpect-ed eff ects: a higher Young’s Modulus creates a fabric that is stiff er and can feel “prickly” on the skin. Other properties are important too: Camira Fabrics3 have discovered that a blend of nettle and wool has very good fi re resistance. 3http://www.camirafabrics.com/content/pages/news.asp?newspage=1&Index=640
5. Investigation into alternative plants (and alternative uses).
Nettles are just one of a large number of alternative sources of fi bre. Are there other suitable sources of fi bre that remain untapped? In addition, natural fi bres have a range of potential uses besides fabric. Building mate-rials (see papercrete project) can be enhanced with natural fi bres, and there are excit-ing possibilities for reinforcing plastics with natural fi bres.
J. Gordon Cook, 1968
Processing bast fi bres follows a route similar to the one shown above. There are some terms here that need defi ning:
Retting
This is a controlled rotting to remove gummy (pectinous) substances which glue fi bres to-gether, which can be carried out in a number of ways: water retting - stalks are left in water, and are acted upon by bacteria dew retting - stalks are left out in the fi eld for 6 weeks, and are acted upon by fungi chemical retting - stalks are placed in chemical solutionsCurrently dew retting is the dominant method; chemical methods tend to damage the fi bres.
Breaking, Scutching and Hackling
Following retting, a sequence of processes to remove the fi bres from the woody stalks is car-ried out (fi rst breaking them, then scraping - or scutching - them off ). Hackling is a combing process to separate long from short fi bres and to remove the remaining woody material.
1. Nettles could be used in integrated farming
The integrated farming system developed by George Chan2 is a system designed to have zero waste. Elements include livestock, crops and fi sh. One of its principle components is the biodigester, which takes livestock waste and produces biogas and fertilizer. One of the “paradoxes” of the Integrated Farming System is that it produces an excess of fertilizer. Excess fertilizer can be potentially damaging to an ecosystem through eutrophication (excessive plant growth in water supplies leading to de-pletion of dissolved oxygen). Nettles would be ideal crops to absorb this fertilizer as they thrive in over-fertilized areas. 2 http://www.scizerinm.org/chanarticle.html
2. Nettles have potential to save water
Nettle fi bres can be as fi ne as cotton, and they are far fi ner than fl ax. However, 7000 - 29, 000 litres of water are used per kg of cotton produced (Soth, 1999). This im-mense water usage can have severe knock on environmental eff ects. Substitution of nettle fi bre for cotton could save large amounts of water.
Nettle, fl ax and wool fi bres (from left to right)
Cross section of a nettle stem. The fi bre bundles are just visible in the dark patches. The stem is hollow, unlike fl ax and many other bast fi bres
Cross section of a fl ax stem, Institut Technique de Lin, Paris
Learning to spin
Fibre from stinging nettles
Bast fi bres are found in the stems of plants. These two microscope photos below show cross sections of fl ax and nettle. The fi bres are found in bundles just inside the outer bark of the plant. Other bast fi bres include ramie, kenaf and jute.
Dr Claire Y Barlow1, Daniel Neal1
1Cambridge University, Department of Engineering, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
