- Email: [email protected]
Bast fibres
Bast fibres: ramie y
1
S. Roy , Latifa Binte Lutfar 1 Former Operations Officer, Dhaka, Bangladesh
3.1
3
Introduction to ramie
Ramie is one of the oldest fibre crops, having been used for at least 6000 years. Ramie fibre is one of the strongest and longest natural fine textile fibres in the world. It is a bast fibre derived from the bast layer of the stem, that is, phloem of the vegetative stalks of the plants.
3.1.1
Origin
This dicot, angiosperm, semiperennial shrub of the Nettle family Urticaceae is a native of the Far East and probably originated in the mountain valleys of southwestern China.
3.1.2
History
Ramie is reported to have been used in mummy cloths in Egypt during 5000e3000 BC. Since prehistoric times, ramie has been used in China, India and Indonesia. It was used for Chinese burial shrouds over 2000 years ago. Ramie was mentioned and praised as grass cloth in the Sanskrit poems of Kalidasa and Ramayana. It was used in the south of Russia about 900 BC. It is said to have been grown in China for many centuries and was one of the principal fibres used in ancient China for making cloth previous to the introduction of cotton around AD 1300. Ramie was first introduced from the East Indies to Holland in 1733, France in 1844, Germany in 1850, England in 1851 and Belgium in 1860. In 1857, ramie plants were introduced into the United States from Java and planted in the Botanical Gardens in Washington. Ramie fibre, also known as China grass, grass linen or Chinese silk, was exported by China to the Western world at the beginning of the 18th century. However, it was not until 1930 that ramie textile production was established on a commercial basis in Western Europe. Commercial ramie production in Brazil first began in the 1930s with production peaking in 1971. In Japan and the Philippines, concentrated efforts were made to produce ramie during the Second World War. With the establishment of sizeable ramie acreages in South Florida, commercial-scale processing equipment was developed and operated successfully from 1946 to 1955. Ramie’s popularity actually increased in the mid-1980s with the fashion emphasis on natural fibres.
y
Deceased author.
Handbook of Natural Fibres. https://doi.org/10.1016/B978-0-12-818398-4.00004-9 Copyright © 2012 Elsevier Ltd. All rights reserved.
62
3.1.3
Handbook of Natural Fibres
Adaptation/agroclimatic conditions
Ramie is adapted to a wide range of latitudes from almost equatorial conditions to about latitude 45 N in Russia. In the temperate areas, between latitudes 25 and 38 N or S, ramie may produce two to three crops annually. In subtropical areas, between 20 and 25 N or S, four to five crops may be harvested, usually with supplementary irrigation. At latitudes below 10 N or S, it may be possible to harvest six or more crops annually, but irrigation must be provided for 2e3 months when there is insufficient rainfall. Ramie has been found to grow well in humid climates under moderate temperature. It requires a uniformly well distributed rainfall of 1500e3000 mm annually. The optimum temperature for good harvest is around 20e31 C, and the relative humidity should be at least 25%. However, the crop is sensitive to waterlogging, frost and strong winds.
3.1.4
Areas of production
China, mainly the central and southern part, leads the world in the production of ramie. Other major producers of ramie fibre are Japan, Taiwan, Brazil, the Philippines, Korea, Indonesia and India.
3.1.5
Economic importance
Ramie, the longest and one of the strongest fine textile fibres, has been grown experimentally throughout the tropical, subtropical and temperate zones of the world. Ramie has been proved quite remunerative when grown under favourable edaphoclimatic conditions. The income generally starts from the second year and continues thereafter. Fibres up to 4%e5% by weight of total biomass may be obtained from ramie. Raw fibre yield of up to 1.6e2.2 ton per hectare may be harvested per year under ideal conditions. However, it is of secondary importance in world trade despite its unique characteristics. This is mainly due to a lack of suitable large-scale fibre extraction equipment until recent years and costly methods of degumming, spinning and weaving of the fibre. Only a small portion of the ramie produced is available in the international market to be imported mainly to Japan, Germany, France and the United Kingdom.
3.2
Types of ramie
Different types of ramie of different quality originate from Boehmeria species of different habitats, some being herbs, some others are trees or shrubs.
Bast fibres: ramie
3.2.1
63
Taxonomy
Ramie is a perennial plant belonging to the genus Boehmeria under Urticaceae or Nettle family of the order Urticales and class Magnoliopsida. There are about 100 species under the genus Boehmeria.
3.2.2
Main species
Boehmeria nivea L. Gaud., commonly known as ‘white ramie’, and Betula utilis generally referred to as B. nivea var. tenacissima and also known as ‘green ramie’ are the two major species of ramie fibre. This green ramie is probably a hybrid of white ramie. The true ramie or China grass also called ‘white ramie’ is the Chinese cultivated plant. The second type, the ‘green ramie’ or rhea, is believed to have originated in the Malay Peninsula. The two varieties differ in their habitat: while B. nivea grows best in temperate and subtropical regions, green ramie occurs in tropical regions. Green ramie or B. utilis is said to give higher fibre yield and stronger fibre than B. nivea, although the fibre quality is not so good in regard with its fineness and colour.
3.2.3
Botanical description
Ramie is the only member of the family used commercially for fibre production and grows well in warm climates. It is a type of shrub. The plant is an erect, usually nonbranching, tall, fast-growing herbaceous perennial reaching 1e2.5 m in height at maturity. The leaves of ramie are heart shaped, 7e15 cm long and 6e12 cm broad and white on the underside of white ramie and green on the underside of green ramie with dense small hairs e this gives a silvery appearance; unlike nettles, the hair strands do not sting.
3.2.4
Cultivation
Fertile, deep loam and well-drained sandy loam soils are suitable for ramie cultivation. Soil rich in organic matter with an optimum pH range from 6 to 7 is preferred (Fig. 3.1). Because this is a perennial plant, plantings are mainly made from asexual plant materials. The seeds of ramie are used only for selection work, as the seedlings rarely develop into plants having desired qualities. Most ramie seedlings are almost unsuitable for fibre. Ramie, thus, may be propagated by the following four methods in order of importance: (1) rhizome cuttings, (2) division of parent rootstock, (3) laying and (4) stem cuttings.
64
Handbook of Natural Fibres
Figure 3.1 A view of a ramie field.
3.2.5
Harvesting
Ramie, being a perennial plant, is normally harvested two to three times a year, but under favourable growing conditions, it can be harvested up to six times per year. Ramie plants produce a large number of unbranched stems from underground rhizomes and have a crop life of 6e20 years. Thus, harvesting of ramie can be done intermittently for up to 20 years. Ramie should be harvested just before flowering or soon after flowering starts. The time of harvesting is important for getting the best fibre and also to obtain maximum fibre yield from the plants. Stems are harvested by either cutting just above the lateral roots or bending the stem.
3.2.6
Fibre extraction
The extraction of ramie fibre occurs in three stages. First, the cortex or bark is removed just after harvesting while the plants are still fresh, by hand or machine. This process is called decortication. Present-day decortication is vastly mechanized. Second, the cortex is scraped to remove most of the outer bark, the parenchyma in the bast layer and some gums and pectins. Finally, the residual cortex material is washed, dried and degummed to obtain the spinnable fibre.
Bast fibres: ramie
3.2.7
65
Degumming
Degumming, the next step, is the process of removal of gum from the decorticated fibre. About 20%e30% of natural adhered gums, holding the fibres in dense strands, are removed so as to make the fibres suitable for spinning and weaving. Degumming may be done by different methods, namely chemical method, microbial method, etc.
3.2.8
Fibre quality and grading
Ramie fibre generally is graded according to length, colour and cleanliness. Top grades usually are washed and sometimes brushed. There is no standard set of grades for ramie fibre, but several countries have set up their own grades. Eight ramie grades are established in China, four in Japan, three in Brazil and four in the Philippines.
3.3
Fibre morphology
Ramie is a multicellular bast fibre, by and large cellulosic in nature, having very little lignin and hemicellulose (Table 3.1). The intercellular binding constituents present in significant amounts are natural gums and pectinous matters. The cells of ramie fibre may be as long as 40e45 cm, cylindrical in nature and characterized by thick walls and narrow, curved lumens. The surface of the cell is marked by distinct ridges.
3.4
Properties of ramie
The physical properties of ramie are given in Table 3.2, while the thermal properties are given in Table 3.3. The raw ramie fibre strand has an average length of 0.61e1 m. The longer fibres are sometimes more than 1.5e2 m in length. These are not single fibres, rather a bundle of shorter single fibres, as in other bast fibres, held together Table 3.1 Chemical composition of ramie. Constituent
Content (%)
Cellulose
68.6e76.2
Hemicellulose
13.1e16.7
Lignin
0.6e0.7
Pectin
1.9
Fats and wax
0.3
Other extractives
6.1
66
Handbook of Natural Fibres
Table 3.2 Physical properties of ramie. Property
Value
Length, L (mm)
60e250
Breadth, B (mm)
15e80
Width (mm)
50
L/B ratio
3500
Fineness (tex)
0.4e0.8
Microfibrillar angle (deg)
7.5
3
Density (mg/m )
1.50
Tenacity (gf/tex)
40e65
Breaking elongation (%)
3.0e4.0 2
Flexural rigidity (dynes.cm )
0.8e1.2
Diameter swelling (%)
12e15
Volume swelling %
32.0
Moisture regain (65%e100% RH)
6.5e17.5
Moisture content (wt%)
8.0
RH, relative humidity.
Table 3.3 Thermal properties of ramie. Property
Values
Specific heat
1.36 103 J/kg/K
Thermal conductivity
427.3 mW/m/K
Heat of combustion
17.5 J/g
Ignition temperature
193 C
Heat of wetting
18.2 Cal
by gummy and pectinous matters. The elementary cells/single fibres of ramie are longer and thicker than all other bast fibres. Ramie is characterized by its exceptionally long ultimate fibre cells that average to about 150 mm in length and highest length/ breadth ratio of ultimate cell (3000). Properly degummed ramie fibre is the longest and the strongest of all vegetable fibres. It is lustrous, possesses high tensile strength, is extremely absorbent, gains strength appreciably when wet and is highly resistant to bacteria, mildew, insect attack and rot. Ramie absorbs moisture and gives it up quickly with almost no shrinking and stretching. Thus, ramie has very good comfort properties and is suitable for summer
Bast fibres: ramie
67
clothes. Very low elasticity, low abrasion resistance, lack of resiliency, stiffness and brittleness, necessary degumming process and high cost are some of the weak points of ramie. Ramie resists action of chemicals better than most of the other natural fibres do. It is dye absorption efficient and fast and has considerable resistance to microbial attack.
3.5
Typical applications
Historically, ramie has been used as a precious material for very fine upper cloth including high-grade kimono cloth, especially in Japan. The Korean traditional costume, hanbok e made of ramie e is renowned for its fineness. Fabrics of ramie are lightweight and silky, similar in appearance to linen and suitable for a wide range of garments and home textiles. Coarse ramie fibres are generally used for making twines and threads, for which its strength and lack of stretch make it most suitable. Because of its high wet strength, quick dryability and considerable resistance to bacterial action, it is very useful for making fishing nets. Ramie is used in many diverse applications such as suiting, shirting, sheeting, dress materials, table cloths, napkins, towels, handkerchiefs, fine furniture upholstery, draperies, mosquito netting, gas mantles, industrial sewing thread, packing materials, fishing nets, fire hose, belting, canvas, marine shaft packing, knitting yarns, hat braids, filter cloths, etc. Because ramie has low elasticity and resilience, it is usually blended with other textile fibres such as cotton, wool, etc. It increases the lustre and strength of cotton blends and reduces shrinkage in wool blends. It is also blended with silk. Shorter fibres and waste, called noils, blended with cotton/stapled rayon are used for making low-grade fabrics such as dish towels. The noils are also used in the manufacture of high-grade specialty papers such as cigarette paper, bank note/currency paper, etc. For the 2010 Prius, Toyota will begin using a new range of plant-derived ecofriendly bioplastics made from cellulose in wood or grass, instead of petroleum. One of the two principal crops to be used is ramie.
3.6
Conclusions
The use of ramie is limited by its price and spinning properties. Apart from any economic or technical reasons, the development of any new fibre needs market development. Despite its excellent properties, wide occurrence/cultivation/adaptation of the plant and reasonable publicity, ramie fibre has not been developed or used to the expected level especially outside China and Japan. Reliable figures relating to production of ramie in China, as the leading ramie producer of the world, are still very difficult to obtain.
68
Handbook of Natural Fibres
The economic factors that prevent farmers from cultivating fibre crops include price level, inconsistency of prices, competition with cheaper synthetic fibres, too few offtakers, uncertain financial returns and the required capital investment in machinery. In addition, the production costs of plant fibres are relatively high compared with manmade fibres.
3.7
Sources of further information and advice
Important literature and organizations supplying information on ramie and other fibre crops are listed below.
3.7.1 • • • • •
Dempsey, J. M. (1975), Fibre Crops. Gainesville, FL: University Press of Florida. European Commission (1994), Industrial Fibre Crops. Studies by Science Research Development, Agro-Industrial Research Diivision, EC. Ghosh, T. (1983), Handbook on Jute. Rome: FAO (Food and Agriculture Organization of the United Nations). Nakamura, A. (2000), Fibre Science & Technology (Translated from Japanese). New Delhi: Oxford & IBH Publishing. NIIR Board of Consultants & Engineers (2005), Natural Fibres: Handbook with Cultivation and Uses. Delhi, India: National Institute of Industrial Research.
3.7.2 • • • • •
Key books
Research and development organizations and groups
Central Research Institute for Jute and Allied Fibres (CRIJAF) Institute of Bast Fibres (IBFC), China Institute of Natural Fibres (INF), Poznan, Poland National Institute for Research on Jute and Allied Fiber Technology (NIRJAFT), India South Indian Textiles Research Institute (SITRA), India.
Further reading Angelini, L.G., Lazzer, A., Levita, G., Fontanelli, D., Bozzi, C., 2000. ‘Industrial crops and products: ramie (Boehmeria nivea (L.) Gaud.) and Spanish Broom (Spartium junceum L.) fibres for composite materials’, Agronomical aspects. Morphol. Mech. Prop. 11 (2e3), 145e161. Barbara, S., Smith, J., 2009. Ramie: Old Fiber e New Image. Ohio State University Extension Fact Sheet, Columbus, Ohio 43210-1295, USA. Available from: http://ohioline.osu.edu/ hyg-fact/5000/5501.html. Guo, Q.Q., Chen, J.R., Yang, R.F., Hu, R.S., 1998. Callus induction and shoot regeneration from leaves of Ramie (Boehmeria nivea Gaud). China’s Fiber Crops 20, 1e4.
Bast fibres: ramie
69
Kozlowski, R., Rawluk, M., Barriga-Bedoya, J., 2005. Ramie, chapter 5. In: Franck, R.R. (Ed.), Bast and other Plant Fibres. Woodhead Publishing, Cambridge, pp. 207e227. Misra, S.P., 2000. A Textbook of Fibre Science and Technology. New Age International (P) Ltd, New Delhi, India. Mohanty, A.K., Misra, M., Hinrichsen, G., 2000. Biofibres, biodegradable polymers and biocomposites: an overview. Macromol. Mater. Eng. 276e7 (1), 1e24. Natural Fibre Ramie, 2009. International Year of Natural Fibres 2009 (IYNF 2009) (Rome, Italy). Saha, M.N., Sen, H.S., 2007. Ramie e A Fibre of Prospect, Bulletin No. 16. CRIJAF (ICAR), West Bengal, India. Susan, B.H., Mary, L.Y., 1989. Ramie: patterns of world production and trade. J. Text. Inst. 80 (4), 493e503. Wood, I., 1999. Ramie: the different bast fibre crop. Aust. New Crops Newsl. (11) Queensland 4069.
1
S. Roy , Latifa Binte Lutfar 1 Former Operations Officer, Dhaka, Bangladesh
3.1
3
Introduction to ramie
Ramie is one of the oldest fibre crops, having been used for at least 6000 years. Ramie fibre is one of the strongest and longest natural fine textile fibres in the world. It is a bast fibre derived from the bast layer of the stem, that is, phloem of the vegetative stalks of the plants.
3.1.1
Origin
This dicot, angiosperm, semiperennial shrub of the Nettle family Urticaceae is a native of the Far East and probably originated in the mountain valleys of southwestern China.
3.1.2
History
Ramie is reported to have been used in mummy cloths in Egypt during 5000e3000 BC. Since prehistoric times, ramie has been used in China, India and Indonesia. It was used for Chinese burial shrouds over 2000 years ago. Ramie was mentioned and praised as grass cloth in the Sanskrit poems of Kalidasa and Ramayana. It was used in the south of Russia about 900 BC. It is said to have been grown in China for many centuries and was one of the principal fibres used in ancient China for making cloth previous to the introduction of cotton around AD 1300. Ramie was first introduced from the East Indies to Holland in 1733, France in 1844, Germany in 1850, England in 1851 and Belgium in 1860. In 1857, ramie plants were introduced into the United States from Java and planted in the Botanical Gardens in Washington. Ramie fibre, also known as China grass, grass linen or Chinese silk, was exported by China to the Western world at the beginning of the 18th century. However, it was not until 1930 that ramie textile production was established on a commercial basis in Western Europe. Commercial ramie production in Brazil first began in the 1930s with production peaking in 1971. In Japan and the Philippines, concentrated efforts were made to produce ramie during the Second World War. With the establishment of sizeable ramie acreages in South Florida, commercial-scale processing equipment was developed and operated successfully from 1946 to 1955. Ramie’s popularity actually increased in the mid-1980s with the fashion emphasis on natural fibres.
y
Deceased author.
Handbook of Natural Fibres. https://doi.org/10.1016/B978-0-12-818398-4.00004-9 Copyright © 2012 Elsevier Ltd. All rights reserved.
62
3.1.3
Handbook of Natural Fibres
Adaptation/agroclimatic conditions
Ramie is adapted to a wide range of latitudes from almost equatorial conditions to about latitude 45 N in Russia. In the temperate areas, between latitudes 25 and 38 N or S, ramie may produce two to three crops annually. In subtropical areas, between 20 and 25 N or S, four to five crops may be harvested, usually with supplementary irrigation. At latitudes below 10 N or S, it may be possible to harvest six or more crops annually, but irrigation must be provided for 2e3 months when there is insufficient rainfall. Ramie has been found to grow well in humid climates under moderate temperature. It requires a uniformly well distributed rainfall of 1500e3000 mm annually. The optimum temperature for good harvest is around 20e31 C, and the relative humidity should be at least 25%. However, the crop is sensitive to waterlogging, frost and strong winds.
3.1.4
Areas of production
China, mainly the central and southern part, leads the world in the production of ramie. Other major producers of ramie fibre are Japan, Taiwan, Brazil, the Philippines, Korea, Indonesia and India.
3.1.5
Economic importance
Ramie, the longest and one of the strongest fine textile fibres, has been grown experimentally throughout the tropical, subtropical and temperate zones of the world. Ramie has been proved quite remunerative when grown under favourable edaphoclimatic conditions. The income generally starts from the second year and continues thereafter. Fibres up to 4%e5% by weight of total biomass may be obtained from ramie. Raw fibre yield of up to 1.6e2.2 ton per hectare may be harvested per year under ideal conditions. However, it is of secondary importance in world trade despite its unique characteristics. This is mainly due to a lack of suitable large-scale fibre extraction equipment until recent years and costly methods of degumming, spinning and weaving of the fibre. Only a small portion of the ramie produced is available in the international market to be imported mainly to Japan, Germany, France and the United Kingdom.
3.2
Types of ramie
Different types of ramie of different quality originate from Boehmeria species of different habitats, some being herbs, some others are trees or shrubs.
Bast fibres: ramie
3.2.1
63
Taxonomy
Ramie is a perennial plant belonging to the genus Boehmeria under Urticaceae or Nettle family of the order Urticales and class Magnoliopsida. There are about 100 species under the genus Boehmeria.
3.2.2
Main species
Boehmeria nivea L. Gaud., commonly known as ‘white ramie’, and Betula utilis generally referred to as B. nivea var. tenacissima and also known as ‘green ramie’ are the two major species of ramie fibre. This green ramie is probably a hybrid of white ramie. The true ramie or China grass also called ‘white ramie’ is the Chinese cultivated plant. The second type, the ‘green ramie’ or rhea, is believed to have originated in the Malay Peninsula. The two varieties differ in their habitat: while B. nivea grows best in temperate and subtropical regions, green ramie occurs in tropical regions. Green ramie or B. utilis is said to give higher fibre yield and stronger fibre than B. nivea, although the fibre quality is not so good in regard with its fineness and colour.
3.2.3
Botanical description
Ramie is the only member of the family used commercially for fibre production and grows well in warm climates. It is a type of shrub. The plant is an erect, usually nonbranching, tall, fast-growing herbaceous perennial reaching 1e2.5 m in height at maturity. The leaves of ramie are heart shaped, 7e15 cm long and 6e12 cm broad and white on the underside of white ramie and green on the underside of green ramie with dense small hairs e this gives a silvery appearance; unlike nettles, the hair strands do not sting.
3.2.4
Cultivation
Fertile, deep loam and well-drained sandy loam soils are suitable for ramie cultivation. Soil rich in organic matter with an optimum pH range from 6 to 7 is preferred (Fig. 3.1). Because this is a perennial plant, plantings are mainly made from asexual plant materials. The seeds of ramie are used only for selection work, as the seedlings rarely develop into plants having desired qualities. Most ramie seedlings are almost unsuitable for fibre. Ramie, thus, may be propagated by the following four methods in order of importance: (1) rhizome cuttings, (2) division of parent rootstock, (3) laying and (4) stem cuttings.
64
Handbook of Natural Fibres
Figure 3.1 A view of a ramie field.
3.2.5
Harvesting
Ramie, being a perennial plant, is normally harvested two to three times a year, but under favourable growing conditions, it can be harvested up to six times per year. Ramie plants produce a large number of unbranched stems from underground rhizomes and have a crop life of 6e20 years. Thus, harvesting of ramie can be done intermittently for up to 20 years. Ramie should be harvested just before flowering or soon after flowering starts. The time of harvesting is important for getting the best fibre and also to obtain maximum fibre yield from the plants. Stems are harvested by either cutting just above the lateral roots or bending the stem.
3.2.6
Fibre extraction
The extraction of ramie fibre occurs in three stages. First, the cortex or bark is removed just after harvesting while the plants are still fresh, by hand or machine. This process is called decortication. Present-day decortication is vastly mechanized. Second, the cortex is scraped to remove most of the outer bark, the parenchyma in the bast layer and some gums and pectins. Finally, the residual cortex material is washed, dried and degummed to obtain the spinnable fibre.
Bast fibres: ramie
3.2.7
65
Degumming
Degumming, the next step, is the process of removal of gum from the decorticated fibre. About 20%e30% of natural adhered gums, holding the fibres in dense strands, are removed so as to make the fibres suitable for spinning and weaving. Degumming may be done by different methods, namely chemical method, microbial method, etc.
3.2.8
Fibre quality and grading
Ramie fibre generally is graded according to length, colour and cleanliness. Top grades usually are washed and sometimes brushed. There is no standard set of grades for ramie fibre, but several countries have set up their own grades. Eight ramie grades are established in China, four in Japan, three in Brazil and four in the Philippines.
3.3
Fibre morphology
Ramie is a multicellular bast fibre, by and large cellulosic in nature, having very little lignin and hemicellulose (Table 3.1). The intercellular binding constituents present in significant amounts are natural gums and pectinous matters. The cells of ramie fibre may be as long as 40e45 cm, cylindrical in nature and characterized by thick walls and narrow, curved lumens. The surface of the cell is marked by distinct ridges.
3.4
Properties of ramie
The physical properties of ramie are given in Table 3.2, while the thermal properties are given in Table 3.3. The raw ramie fibre strand has an average length of 0.61e1 m. The longer fibres are sometimes more than 1.5e2 m in length. These are not single fibres, rather a bundle of shorter single fibres, as in other bast fibres, held together Table 3.1 Chemical composition of ramie. Constituent
Content (%)
Cellulose
68.6e76.2
Hemicellulose
13.1e16.7
Lignin
0.6e0.7
Pectin
1.9
Fats and wax
0.3
Other extractives
6.1
66
Handbook of Natural Fibres
Table 3.2 Physical properties of ramie. Property
Value
Length, L (mm)
60e250
Breadth, B (mm)
15e80
Width (mm)
50
L/B ratio
3500
Fineness (tex)
0.4e0.8
Microfibrillar angle (deg)
7.5
3
Density (mg/m )
1.50
Tenacity (gf/tex)
40e65
Breaking elongation (%)
3.0e4.0 2
Flexural rigidity (dynes.cm )
0.8e1.2
Diameter swelling (%)
12e15
Volume swelling %
32.0
Moisture regain (65%e100% RH)
6.5e17.5
Moisture content (wt%)
8.0
RH, relative humidity.
Table 3.3 Thermal properties of ramie. Property
Values
Specific heat
1.36 103 J/kg/K
Thermal conductivity
427.3 mW/m/K
Heat of combustion
17.5 J/g
Ignition temperature
193 C
Heat of wetting
18.2 Cal
by gummy and pectinous matters. The elementary cells/single fibres of ramie are longer and thicker than all other bast fibres. Ramie is characterized by its exceptionally long ultimate fibre cells that average to about 150 mm in length and highest length/ breadth ratio of ultimate cell (3000). Properly degummed ramie fibre is the longest and the strongest of all vegetable fibres. It is lustrous, possesses high tensile strength, is extremely absorbent, gains strength appreciably when wet and is highly resistant to bacteria, mildew, insect attack and rot. Ramie absorbs moisture and gives it up quickly with almost no shrinking and stretching. Thus, ramie has very good comfort properties and is suitable for summer
Bast fibres: ramie
67
clothes. Very low elasticity, low abrasion resistance, lack of resiliency, stiffness and brittleness, necessary degumming process and high cost are some of the weak points of ramie. Ramie resists action of chemicals better than most of the other natural fibres do. It is dye absorption efficient and fast and has considerable resistance to microbial attack.
3.5
Typical applications
Historically, ramie has been used as a precious material for very fine upper cloth including high-grade kimono cloth, especially in Japan. The Korean traditional costume, hanbok e made of ramie e is renowned for its fineness. Fabrics of ramie are lightweight and silky, similar in appearance to linen and suitable for a wide range of garments and home textiles. Coarse ramie fibres are generally used for making twines and threads, for which its strength and lack of stretch make it most suitable. Because of its high wet strength, quick dryability and considerable resistance to bacterial action, it is very useful for making fishing nets. Ramie is used in many diverse applications such as suiting, shirting, sheeting, dress materials, table cloths, napkins, towels, handkerchiefs, fine furniture upholstery, draperies, mosquito netting, gas mantles, industrial sewing thread, packing materials, fishing nets, fire hose, belting, canvas, marine shaft packing, knitting yarns, hat braids, filter cloths, etc. Because ramie has low elasticity and resilience, it is usually blended with other textile fibres such as cotton, wool, etc. It increases the lustre and strength of cotton blends and reduces shrinkage in wool blends. It is also blended with silk. Shorter fibres and waste, called noils, blended with cotton/stapled rayon are used for making low-grade fabrics such as dish towels. The noils are also used in the manufacture of high-grade specialty papers such as cigarette paper, bank note/currency paper, etc. For the 2010 Prius, Toyota will begin using a new range of plant-derived ecofriendly bioplastics made from cellulose in wood or grass, instead of petroleum. One of the two principal crops to be used is ramie.
3.6
Conclusions
The use of ramie is limited by its price and spinning properties. Apart from any economic or technical reasons, the development of any new fibre needs market development. Despite its excellent properties, wide occurrence/cultivation/adaptation of the plant and reasonable publicity, ramie fibre has not been developed or used to the expected level especially outside China and Japan. Reliable figures relating to production of ramie in China, as the leading ramie producer of the world, are still very difficult to obtain.
68
Handbook of Natural Fibres
The economic factors that prevent farmers from cultivating fibre crops include price level, inconsistency of prices, competition with cheaper synthetic fibres, too few offtakers, uncertain financial returns and the required capital investment in machinery. In addition, the production costs of plant fibres are relatively high compared with manmade fibres.
3.7
Sources of further information and advice
Important literature and organizations supplying information on ramie and other fibre crops are listed below.
3.7.1 • • • • •
Dempsey, J. M. (1975), Fibre Crops. Gainesville, FL: University Press of Florida. European Commission (1994), Industrial Fibre Crops. Studies by Science Research Development, Agro-Industrial Research Diivision, EC. Ghosh, T. (1983), Handbook on Jute. Rome: FAO (Food and Agriculture Organization of the United Nations). Nakamura, A. (2000), Fibre Science & Technology (Translated from Japanese). New Delhi: Oxford & IBH Publishing. NIIR Board of Consultants & Engineers (2005), Natural Fibres: Handbook with Cultivation and Uses. Delhi, India: National Institute of Industrial Research.
3.7.2 • • • • •
Key books
Research and development organizations and groups
Central Research Institute for Jute and Allied Fibres (CRIJAF) Institute of Bast Fibres (IBFC), China Institute of Natural Fibres (INF), Poznan, Poland National Institute for Research on Jute and Allied Fiber Technology (NIRJAFT), India South Indian Textiles Research Institute (SITRA), India.
Further reading Angelini, L.G., Lazzer, A., Levita, G., Fontanelli, D., Bozzi, C., 2000. ‘Industrial crops and products: ramie (Boehmeria nivea (L.) Gaud.) and Spanish Broom (Spartium junceum L.) fibres for composite materials’, Agronomical aspects. Morphol. Mech. Prop. 11 (2e3), 145e161. Barbara, S., Smith, J., 2009. Ramie: Old Fiber e New Image. Ohio State University Extension Fact Sheet, Columbus, Ohio 43210-1295, USA. Available from: http://ohioline.osu.edu/ hyg-fact/5000/5501.html. Guo, Q.Q., Chen, J.R., Yang, R.F., Hu, R.S., 1998. Callus induction and shoot regeneration from leaves of Ramie (Boehmeria nivea Gaud). China’s Fiber Crops 20, 1e4.
Bast fibres: ramie
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Kozlowski, R., Rawluk, M., Barriga-Bedoya, J., 2005. Ramie, chapter 5. In: Franck, R.R. (Ed.), Bast and other Plant Fibres. Woodhead Publishing, Cambridge, pp. 207e227. Misra, S.P., 2000. A Textbook of Fibre Science and Technology. New Age International (P) Ltd, New Delhi, India. Mohanty, A.K., Misra, M., Hinrichsen, G., 2000. Biofibres, biodegradable polymers and biocomposites: an overview. Macromol. Mater. Eng. 276e7 (1), 1e24. Natural Fibre Ramie, 2009. International Year of Natural Fibres 2009 (IYNF 2009) (Rome, Italy). Saha, M.N., Sen, H.S., 2007. Ramie e A Fibre of Prospect, Bulletin No. 16. CRIJAF (ICAR), West Bengal, India. Susan, B.H., Mary, L.Y., 1989. Ramie: patterns of world production and trade. J. Text. Inst. 80 (4), 493e503. Wood, I., 1999. Ramie: the different bast fibre crop. Aust. New Crops Newsl. (11) Queensland 4069.