1 INTRODUCTION
Various parts of plants like woody core, bast, leaf, cane, straw from cereals, grass and seed can be used in applications like building materials, particleboards, insulation boards, human food and animal feed, cosmetics, medicine and sources of other bio-polymers and "fine chemicals". They do not damage the ecosystem, they can grow in different climatic zones and they recycle the carbon dioxide for the atmosphere. These plants can contribute to a better agricultural balance in Europe and they will contribute to the growing demand from an expanding population for cellulosic pulp in the next millennium. Some of these green plants like flax and hemp can be used for cleaning soil, polluted by heavy metals, by extracting and removing cadmium, lead, copper and others.
The estimated world-wide production of fibrous raw materials from agricultural crops is provided in Table 1. Other possible sources of straw, which could be used as raw materials for applications such as composites and as energy crops are given in Table 2.
Table 1: Estimated global tonnage of fibrous raw materials from agricultural crops
2 TEXTILE AND NON-TEXTILE APPLICATIONS
2.1 Textile fibres
Green fibres in textiles provide for healthy, comfortable clothing, which ultimately will be fully biodegradable.
There are two parallel textile fibre technologies:
2.1.1 Typical long staple fibre production and processing.
Though difficult in handling, traditional long flax, ramie and hemp are still produced and processed by slightly modernized methods. Flax and ramie provide yarns of high strength, lustre and low linear mass.
These products include:
To profit from immense progress in this spinning machinery green fibres must become cleaner, shorter, thinner, and softer. The finer the fibre, the narrower fineness and staple diagram, the easier the processing, the higher the bast content, the better the quality of yarns and products.
In some technologies the process of fibre modification starts in the field. Some combine mechanical and chemical treatments like new US Patent 5 666 696. A new process developed by Rieter-Elitex bast breaking, cleaning and refining machine "RCZ-120-3" combines all the three processes very effectively into one. The new, mainly blended bast fibre yarns differ from traditional ones. They are of lower linear mass, lower tenacity yet of higher elongation and can be spun at higher speeds.
These yarns can be used in a wide range of woven and knitted apparels, underwear, active wear, healthy textile shoes, socks and other textile items. Special treatmenst like enzymatic; liquid ammonia, plasma and corona treatment provides new promising features and properties of fibres and fabrics like "fineness" and crease resistance. In conclusion, green fibres now are better adapted to modern processing techniques, which develop new clothing and home furnishing items, bio-degradable non-wovens and geo-textiles.
2.2 Green fibres for non-textile products
Science and technology continue to make a significant impact on the potential use of green resources.
2.2.1 Green fibres/bast fibrous plants for pulp
In the cellulose industry interest is growing in production of pulp and paper from agro-based lignocellulosic raw materials such as bagasse, bamboo, reeds, esparto, hemp, flax, abaca, sisal, grass, etc. The amount of pulp made of non-wood resources is still growing. In 1995 the capacity of non-wood pulp production was 6.8 percent in total, and in 1998 was about 11 percent. The contribution of cellulose of agro-plant origin to the world production of pulp and paper is growing. Further increases in the contribution of agro-plant cellulose is foreseen and it should reach about 15 percent in 2010 (when the total production is estimated to be about 480 million tons). In addition to cellulose, the main components of lignocellulosics are lignin, hemicelluloses, and pentosans.
An example of the use of jute for pulp (for fibres, but also suitable for non-textile applications) is given by the South India Viscose Company. In the U. S. when the Department of Agriculture was searching for an agricultural source of fibre for paper industries, kenaf was chosen as a prime candidate to prolong the life of North America forests.
Similar developments are in progress through the entire tropical zone and involve jute, kenaf, sisal, abaca, as well as crops like bamboo, reeds, esparto, grass and badges.
The Institute of Natural Fibres developed an environmentally safe technology for producing bleached pulp from hemp grown on land polluted by metallurgic industry.
The productivity of hemp biomass is very high: 2 to 2.5 times higher than can be produced from the same area of forest. The concentration of alpha-cellulose in the raw fibre (bast), reaches the level of 90 percent while the concentration of cellulose in softwood and hardwood ranges from 50 to 54 percent.
Promising solvent methods for the pulping of annual plants include:
Sources FAO Report, Assessed on 22 February 2016
Various parts of plants like woody core, bast, leaf, cane, straw from cereals, grass and seed can be used in applications like building materials, particleboards, insulation boards, human food and animal feed, cosmetics, medicine and sources of other bio-polymers and "fine chemicals". They do not damage the ecosystem, they can grow in different climatic zones and they recycle the carbon dioxide for the atmosphere. These plants can contribute to a better agricultural balance in Europe and they will contribute to the growing demand from an expanding population for cellulosic pulp in the next millennium. Some of these green plants like flax and hemp can be used for cleaning soil, polluted by heavy metals, by extracting and removing cadmium, lead, copper and others.
The estimated world-wide production of fibrous raw materials from agricultural crops is provided in Table 1. Other possible sources of straw, which could be used as raw materials for applications such as composites and as energy crops are given in Table 2.
Table 1: Estimated global tonnage of fibrous raw materials from agricultural crops
Crop
|
Plant component
|
Availability
|
'000 tonnes
| ||
| Cereals | straw: | |
| barley | straw |
218.5
|
| oats | straw |
50.8
|
| rice | straw |
465.2
|
| rye | straw |
41.9
|
| wheat | straw |
739.7
|
| corn | stalks |
727.3
|
| cottons | lint, |
18.0
|
| linters |
2.3
| |
| stalks |
35.9
| |
| mote |
900
| |
| Bast fibrous plants*/ | straw |
25.0*/
|
| Seed grass | straw |
2.0
|
| Oil flax | straw |
3.0
|
| Sorghum | stalks |
104.7
|
| Sugarcane1 | Bagasse1 |
100.2
|
| Total |
2535.4
|
Source: Rowell, Young and Rowell, (1997). */Estimated by INF1. Leão, A. (1998)Table 2: Other possible sources of straw, which could be used as raw materials
Annual ryegrass
|
Lupins
|
Sunflower
|
| Bamboo | Meadow foxtail | Pseudocereals |
| Black locust | Miscanthus | Tall fescue |
| Broom | Rape | Timothy |
| Cardoon | Root chicory | Topinambur |
| Common reed | Rosin weed | Willow and poplar |
| Cordgrass | Safflower | Amaranth |
| Eucalyptus | Soybean | Quinoa |
| Giant knotweed | Salicornia | Microalgae |
| Giant reed | Triticale | |
| Groundnut |
2 TEXTILE AND NON-TEXTILE APPLICATIONS
2.1 Textile fibres
Green fibres in textiles provide for healthy, comfortable clothing, which ultimately will be fully biodegradable.
There are two parallel textile fibre technologies:
2.1.1 Typical long staple fibre production and processing.
Though difficult in handling, traditional long flax, ramie and hemp are still produced and processed by slightly modernized methods. Flax and ramie provide yarns of high strength, lustre and low linear mass.
These products include:
- 100 percent linen or ramie knitted apparels. Perfect hygiene and comfort properties make them specially attractive for hot, humid climates;
- 100 percent linen and ramie fabrics - from almost transparent to terry type, boasting high "Wash and Wear" properties when finished with liquid ammonia
- 100 percent linen anti-bedsore bedding, developed at the Institute of Natural Fibres for ill and aged people. Tests conducted in Polish Academic Clinic showed that no bedsores occurred when such bedding was used
- 100 percent linen knitted bedding which, according to the research, provides the deepest sleep and best mood recovery. These tests initiated by Japanese scientists are conducted at the Institute of Natural Fibres, Poznan;
- hemp and jute sport and Friday-wear
- hemp and linen hygienic, comfortable boots and shoes.
To profit from immense progress in this spinning machinery green fibres must become cleaner, shorter, thinner, and softer. The finer the fibre, the narrower fineness and staple diagram, the easier the processing, the higher the bast content, the better the quality of yarns and products.
In some technologies the process of fibre modification starts in the field. Some combine mechanical and chemical treatments like new US Patent 5 666 696. A new process developed by Rieter-Elitex bast breaking, cleaning and refining machine "RCZ-120-3" combines all the three processes very effectively into one. The new, mainly blended bast fibre yarns differ from traditional ones. They are of lower linear mass, lower tenacity yet of higher elongation and can be spun at higher speeds.
These yarns can be used in a wide range of woven and knitted apparels, underwear, active wear, healthy textile shoes, socks and other textile items. Special treatmenst like enzymatic; liquid ammonia, plasma and corona treatment provides new promising features and properties of fibres and fabrics like "fineness" and crease resistance. In conclusion, green fibres now are better adapted to modern processing techniques, which develop new clothing and home furnishing items, bio-degradable non-wovens and geo-textiles.
2.2 Green fibres for non-textile products
Science and technology continue to make a significant impact on the potential use of green resources.
2.2.1 Green fibres/bast fibrous plants for pulp
In the cellulose industry interest is growing in production of pulp and paper from agro-based lignocellulosic raw materials such as bagasse, bamboo, reeds, esparto, hemp, flax, abaca, sisal, grass, etc. The amount of pulp made of non-wood resources is still growing. In 1995 the capacity of non-wood pulp production was 6.8 percent in total, and in 1998 was about 11 percent. The contribution of cellulose of agro-plant origin to the world production of pulp and paper is growing. Further increases in the contribution of agro-plant cellulose is foreseen and it should reach about 15 percent in 2010 (when the total production is estimated to be about 480 million tons). In addition to cellulose, the main components of lignocellulosics are lignin, hemicelluloses, and pentosans.
An example of the use of jute for pulp (for fibres, but also suitable for non-textile applications) is given by the South India Viscose Company. In the U. S. when the Department of Agriculture was searching for an agricultural source of fibre for paper industries, kenaf was chosen as a prime candidate to prolong the life of North America forests.
Similar developments are in progress through the entire tropical zone and involve jute, kenaf, sisal, abaca, as well as crops like bamboo, reeds, esparto, grass and badges.
The Institute of Natural Fibres developed an environmentally safe technology for producing bleached pulp from hemp grown on land polluted by metallurgic industry.
The productivity of hemp biomass is very high: 2 to 2.5 times higher than can be produced from the same area of forest. The concentration of alpha-cellulose in the raw fibre (bast), reaches the level of 90 percent while the concentration of cellulose in softwood and hardwood ranges from 50 to 54 percent.
Promising solvent methods for the pulping of annual plants include:
- Acetosolve (Germany) - using solution of 93 - 85 percent acetic acid and addition of 0.1 percent HCL, and MILOX (Finland) - using formic acid;
- Alcell method, employing ethyl alcohol;
- Steam explosion pulping (SEP) (Canada) - using chemical impregnated raw material cooked with saturated steam;
- Ethanol pulping (Egypt) - using ethanol/water, ethanol/water/NAOH solutions;
- Peroxy-compounds-using peroxymonosulphate anion (HSO5)
- The Alcell® process developed by Repap Enterprises Inc., Canada. Trials using organic solvents to dissolve and separate wood components was first documented in early 1990's. The new method consisting in the treatment with ethanol at 195°C under the pressure of 29 bars appeared in 1990.
Sources FAO Report, Assessed on 22 February 2016
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