Dr. N.N.Mahapatra B.Sc ( Hons), B.Sc (Tech )(Bom), M.Sc (Chem), Ph.D (Chem), M.B.A (IMM,Cal), C.Col FSDC (UK), CText FTI (Manchester), Int Trg (Australia), Sen Mem, AATCC (USA), FAIC (USA) FIC, FTA, FICS, FIE, FIIChE, MISTE (INDIA). President COLORANT LTD
Natural fibers have been used historically to produce our clothes, carpets, cordage, paper, ship sails, and insulation and building materials. The use of natural fibers, both plant, and animal, to meet our needs go back thousands of years and play a significant role in history. In the history of natural fibers, one of the oldest recorded uses of plant fiber for fabrics is the use of hemp which was already being cultivated in China in 2800 BC. Like agriculture, textiles have been a fundamental part of human life since the dawn of civilization. Fragments of cotton articles dated from 5000 BC have been excavated in Mexico and Pakistan. According to Chinese tradition, the history of silk begins in the 27th century BC. The oldest wool textile, found in Denmark, dates from 1500 BC, and the oldest wool carpet, from Siberia, from 500 BC. Fibers such as jute and coir have been cultivated since antiquity.
In the last hundred years or so there has been a turn away from natural fibers towards synthetic materials, mostly derived from petrochemicals. This change was a result of the technological revolution and the short-term economic advantages of synthetics.
Why natural fibers are getting momentum again:
The pendulum is once again swinging towards natural fibers and we are now seeing a growing movement away from petrochemical-based fibers back to natural fibers. There are several reasons for this. Petrochemical based fiber production has undergone continuing rising costs. Synthetic fibers rely on precious non-renewable resources and incur environmental costs in their production. Petrochemical based products pose a health risk in most applications, both from direct exposure and also from secondary exposure through the soil, water, and air pollution.
Natural fibers are produced from either plant, animal or insect sources. They are being extracted from plant leaves and inner bark or fruit seed crop, or from animal wool/ hair, or insect cocoon or from the mineral product. Plant sources of fiber include cotton, hemp, pineapple, ramie, sisal, flax, jute, coconut and banana (abaca). Animal sources of fiber include sheep, alpaca, llama, goat, and camel, and can be either wool, hair or leather. Insect fiber is predominantly from silkworm cocoons.
The return to natural fibers to meet our fiber needs is only one part of the change that is required if we want to achieve sustainable living. We must also return to traditional methods of production back to chemical-free and organic production methods. Cotton is one of the most environmentally expensive fibers to produce. Cotton production is the second-largest agricultural use of pesticides in the world with five of the nine top “nasty” pesticides used. Cyanide, dicofol, naled, and propargite are commonly used in cotton production and these chemicals are known cancer-causing chemicals.
Natural fibers are greatly elongated substances produced by plants and animals that can be spun into filaments, thread or rope. Woven, knitted, matted or bonded, they form fabrics that are essential to society. While the methods used to make fabrics have changed greatly since then, their functions have changed very little; today, most natural fibers are still used to make clothing and containers and to insulate, soften and decorate our living spaces. Increasingly, however, .traditional textiles are being used for industrial purposes as well as in components of composite materials, in medical implants, and geo-and agro-textiles.
Banana fiber and its history:
The Banana family (Musaceae) is one of the plants which provide natural fiber. The genus Musa belongs to the Musaceae, a family of monocotyledons. It contains between 60-80 species, including the cultivated banana plant and several wild bananas.
The Musaceae family of plants is one of the most useful in the world. It provides us with all manner of foods and industrial raw materials. Musa sapientum, for example, gives us the banana; Musa textiles are a source of the papermaking and cordage fiber abaca or Manila hemp. This vegetable leaf fiber is derived from the Musa textiles plant.
The banana plant is indigenous to the Philippine Islands; native islanders were making textiles from its fibers when Magellan visited the islands in 1521 during his circumnavigation of the globe. During the early 19th century, supplies of banana began to reach the Western world, and its value as a cordage fiber was quickly appreciated. It was better than hemp for many purposes, particularly in marine ropes and hawsers.
Despite the many attempts that have been made to establish banana production in other parts of the world, the Philippine Islands remain the chief source of the fiber. In the Philippines, abaca is planted over an area estimated at 130,000 hectares. It is also cultivated in Africa, Malaysia, Indonesia, and Costa Rica, and has been successfully introduced into Ecuador, now the world’s No 2 producer of the fiber. In 2007, the Philippines produced 60,000 tons of abaca fiber.
Bangladesh also cultivates a huge number of banana plants having all the potential to become a major producer of banana fiber.
Production and processing of banana fiber:
As will be seen later, fiber can also be obtained from the edible banana plant, and there are, moreover, various species of wild banana which produce a fiber that is used for local purposes in various countries. The plant is of great economic importance, being harvested for its fiber, once generally called Manila hemp, extracted from the leaf sheath around the trunk. On average, the plant grows about 20 feet (6 meters) tall.
For fiber production, the most important of the Musa species is Musa textiles Nee, from which Abaca fiber, also known as Manila hemp, is obtained. As Musa textiles are a member of the banana genus, in appearance it closely resembles the banana, and indeed the plants can easily be mistaken for each other. There are one or two differences, however, by which the two plants can be distinguished. Abaca stalks are generally more slender, and the leaves are smaller, narrower, and rather more tapered, than those of the banana plant.
Abaca is extracted from the leaf sheath around the trunk of the abaca plant (Musa textiles), a close relative of the banana and native to the Philippines. Each sheath contains a thin layer of fiber. The plant comprises a cluster of sheath-like leaf stalks.
Harvesting abaca is very labor-intensive. Each stalk must be cut into strips which are then scraped (usually by hand) to remove the pulp. The long white fibers are then washed and dried and baled for transport. For use in blends for the automobile industry, high-quality fiber is spun into yarn, put onto bobbins and exported. The fiber is obtained from the outer layer of the leaf.
The Banana plant has long been a source of fiber for high-quality textiles. In Japan, the cultivation of banana for clothing and household dates back to at least the 13th century. In the Japanese system, leaves and shoots are cut from the plant periodically to ensure softness. The harvested shoots must first be boiled in lye to prepare the fibers for the making of the yarn. These banana shoots produce fibers of varying degrees of softness, yielding yarns and textiles with differing qualities for specific uses. For example, the outermost fibers of the shoots are the coarsest, and are suitable for tablecloths, whereas the softest innermost fibers are desirable for kimono and kamishimo. This traditional Japanese banana cloth-making process requires many steps, all performed by hand.
In another system employed in Nepal, the trunk of the banana plant is harvested instead, small pieces of which are subjected to a softening process, mechanical extraction of the fibers, bleaching, and drying. After that, the fibers are sent to the Kathmandu Valley for the making of high-end rugs with a textural quality similar to silk. These banana fiber rugs are woven by the traditional Nepalese hand-knotted methods and are sold RugMark certified.
The fiber is extracted by separating the ribbons of fibre from the layers of pulp. These ribbons, which are known as tuxies, are then drawn under a knife, usually made of metal, and the residual pulp is removed from the fiber, which is then hung up to dry.
Processing occurs when it is separated mechanically decorticated into lengths varying from 3 to 9 feet. The leaves grow from the trunk of the plant, and the bases of the leaves form a sheath (covering) around the trunk; there are approximately 25 of these, with 5 cm in diameter and from 12 to 25 leaves with overlapping petioles, covering the stalk to form a shrub, “false trunk” or pseudo trunk about 30 to 40 cm in diameter. They grow in succession, with the oldest growing from the bottom of the trunk and successively younger ones from the top. The sheaths contain valuable fiber.
The coarse fibers range from 5 to 11 ½ feet (1.5 to 3.5 meters) in length. They are composed primarily of plant materials such as cellulose, lignin, and pectin. After the fiber has been separated, it is sold under the name Manila, the capital of the Philippines.
The plant is normally grown in well-drained loamy soil, using pieces of mature root planted at the start of the rainy season. Growers harvest Abaca fields every three to eight months after an initial growth period of 18- 25 months and a total lifespan of about 10 years. Harvest generally includes having several operations concerning the leaf sheaths;
- Tuxying (separation of the primary and secondary sheath)
- Stripping (getting the fibers).
- Drying (usually following tradition of sun-drying).
The fibers can then be spun into twines or cordage. In the process of cleaning abaca fiber, the use of coarsely serrated stripping knives and the lack of proper tension on the stripping knife result in the production of coarse low-grade fiber. Delay and carelessness in drying affect both the color and strength of the fiber.
Structure and properties:
Abaca is very strong and has great luster. Abaca rope is very durable, flexible and is very resistant to damage from saltwater. It is classified as a hard fiber, along with coir, henequen, and sisal.
Abaca has a good natural luster. Its color depends upon the conditions under which it has been processed; good quality abaca is off-white, whereas some poor quality fiber is nearly black. It is strong and sufficiently flexible to provide a degree of ‘give‘when used in rope. Individual fiber cells are cylindrical and smooth-surfaced. They are as much as 6 mm (¼ in) long, are regular in width. The ends taper gradually to a point.
In cross-section, the fibers are polygonal and cell walls thin. The lumen is large and distinct; it is round and uniform in diameter although both fiber and lumen show occasional constrictions. In places, the lumen contains granular bodies.
Abaca fibers are largely cellulose (about 77% of moisture-free fiber) but are coated with considerable amounts of lignin (about 9 %). The individual fibers can be freed by boiling the strands of alkali. Abaca fiber is bleached and dyed as per other cellulosic fibers.
Uses of banana fibers:
One traditional use of the coarse abaca fibers, which range up to 3 meters in length and have very high tensile strength, was as cordage, especially for ship’s rigging. Today, most abaca is pulped and processed into tea bags, vacuum bags, a casing for sausages, banknotes, cigarette papers and high-quality writing paper. Recently, research engineers patented a novel mixture of polypropylene thermoplastic and abaca yarn for use in automobile components, including external panels. Once a favored source of rope, abaca shows promise as an energy-saving replacement for glass fibers in automobiles.
The fiber was originally used for making twines and ropes as well as the Manila envelope; now most Abaca is pulped and used in a variety of paper–like products including filter paper and banknotes. It can be used to make handicrafts like bags, carpets, clothing, and furniture.
Some of the fine inner fibers from the abaca leaf–stalk is used directly, without spinning, for making delicate, lightweight, yet strong fabrics. These fabrics are used in the Philippines for clothing, and for hats and shoes. Some abaca is used for carpets, table mats, etc.
In South India lot of Banana, cultivation is found which has helped the local people to extract fiber from the leaves of the banana plant which is being used in making banana yarn and blended with cotton, and synthetics and various lightweight fabrics are produced. It has to be popularized further in India similar to the Philippines.