Spandex is a synthetic polymer. It is an elastomer, which means it can be stretched to a certain degree and it recoils when released. These fibers are superior to rubber because they are stronger, lighter, and more versatile. This unique elastic property of the spandex fibers is a direct result of the material's chemical composition. The fibers are made up of numerous polymer strands.
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Environmental and Ethical Issues In The Production Of Natural Fabrics and FibresVIDEO ON THE TOPIC: From wood cellulose to textile fibres
Ramie fibre comes under bast fibre category, which can be classified as underutilised fibres. The high potential of ramie fibre is not fully exploited due to various techno-economic reasons. It is one of the strongest natural fibres having rich cellulose content.
Apart from textile uses, ramie fibre can be utilised for the production of various diversified products. Still in present scenario, there is much scope for research and development on this valuable fibre.
This study briefs the extraction, mechanical processing, fibre properties and value addition of ramie fibre. Natural fibres are gaining importance day by day in all over the world. They are not only using for making clothing, but also finds other diversified applications. Among nature fibres, cotton occupied supreme position in both production and consumption. Lignocellulosic fibres like flax and ramie are also getting popularized in the current era.
Ramie fibre is one of the premium and oldest textile vegetable fibres. It was used in mummy cloths in Egypt during the period BC and has been grown in China for many centuries. Ramie was one of the principal plant fibres used in the orient for making cloth before the introduction of cotton, which took place in China about AD 1. Ramie has been used as a textile fibre in China and Southern Asia for centuries and it is said to have been known in ancient Egypt.
It is also known as china grass 2. Ramie fibre is a bast fibre obtained from the inner bark of the ramie stem 3. The total lifespan of the crop ranges from years 4. Generally it grows up to a height of m, the leaves are heart-shaped, cm long and cm broad and white on the underside with dense small hairs. During this period, it can be harvested up to 6 times in a year. China holds the monopoly in both production and exporting of ramie.
Earlier so many countries tried to cultivate ramie, some of them withdrawn the cultivation due to some inevitable situations. Most of the ramie fibre extracted is used in producing countries and only a small percentage reaches international markets.
It possesses highest strength and length, good durability and absorbency with excellent lustre. These characteristics make it suitable for use in the manufacture of wide variety of textiles and value added products 5 , 6. Fabrics made from ramie fibre are comfortable to wear and looks like linen. Today some of the fashion designers are showing much interest in ramie fabric due to its unique properties. Apart from that, ramie also find application in sacks, carpets, reinforced polymers, twine, handicrafts, paper, cordage, gas mantles, fishing nets and marine packaging.
In China elsewhere in the far East, ramie is used for a number of purposes such as clothing, table-cloths, handkerchiefs, etc. In Japan, ramie is used for canvas, suit-cloth, mat-edge, cloth and a large number of other purposes 7.
China is the biggest producer of ramie fibre followed by Brazil and Philippines Fig. The fibre yield and area of cultivation is shown in the Fig. Coming to the present condition of cultivation in India, very few areas of states like West Bengal and Assam is showing some interest and the production is very minimal. There may be several reasons behind it, especially, the difficulties associated with decortication, degumming, pest and diseases.
The adaptation of the plant to soil is another retarding factor. However, profitable growing for fibre purpose is based on the principle of as many cutting a year as possible and to produce the best results the plants requires a favourable climate with steady high temperature , a humid atmosphere and a well-distributed annual rainfall of not less than 1. The photograph of ramie plant is shown in Fig. There are 2 major varieties of ramie plants.
White ramie and green ramie as shown in Fig. Harvesting: The stems are green until they are mature, but then they begin to turn brown, starting at the bottom. The right time for harvesting is judged by the colour of the stems and the slowing down of their growth. The plants should be cut when the flower begins to fall and the seed to form. As the plant matures, the number of stalks increases with a corresponding increase in yields up to the fourth year, an average of 4, 7, 10 and 13 t of green stalks may be harvested per acre in each of the first 4 years, respectively and t annually thereafter.
First harvesting can be done after 17 days of planting and followed by days for the succeeding harvests. The highest yield is attained in the third and fourth years and maintained until the plant is about six years old 8. Harvesting is done either by manually or by using mechanical harvesters.
It is important that ramie should be harvested at the right time if the best fibre is to be obtained. If the stems are allowed to become too mature, lignification takes place. After harvesting, if the ribbons are not to be stripped from the stalks right away and the fibre extracted, the cut stems or ribbons should be dried as soon as possible, to prevent bacterial attack. The fibre is derived from the inner bast tissues of the stem. The bast of ramie cannot be removed from the woody tissue in which it is embedded by a simple retting process such as is used for flax, hemp and jute.
Instead, it must first undergo a severe pounding or scraping to remove the outer bark, which is administered by hand or by one of the many types of decorticating machines.
The decorticator and decorticated ramie fibre is shown as in Fig. By decortication, the outer bark, the central woody core and some portion of the gums and waxes of the bast are mechanically removed. In principle, any machine which is used for sisal or kenaf decortications can be adjusted for ramie. The decorticator consists of a beater or breaker plate and a metal drum, which is equipped with steel beater blades or knives that are set at equal intervals on the periphery of the drum. The quality of decortication and fibre recovery also depend largely on the efficiency of the operator as well as condition of the plants.
Stalks becoming dry after harvest cannot be properly decorticated. Decortication should be completed on the day of harvest and if there are some left over, they should be kept moist by sprinkling water till decortications is done on the following day. Decortication is to be done immediately after harvest and therefore, a harvesting schedule is planned in relation to the decortications capacity of the machines used 9. A number of small machines have been designed in various countries with the objective of extracting bast fibre from the green stems of jute and similar fibre plants and thus eliminating the need of retting.
Decorticators developed for ramie include small mobile types suitable for use in the field and larger machines designed for central operation. Use of decorticators in the field saves the cost of transporting unwanted plant material to soil Some have been in use for a long while, but they all have drawbacks for commercial big scale production.
Either the fibre is imperfectly cleaned so that it can only be put to use for limited local purposes, or the output is much too low, or there too much wastage of fibre during the process of decortications The ribbons of partially separated but not yet degummed fibre, are known as "China grass" and it is in this form that ramie is normally exported from China to European and other markets. The extracted fibrous material, after washing, should be immediately dried or degummed to prevent the development of mildew.
As mentioned above, ramie is not retted in the same way as are other stem fibres such as jute, hemp, flax, etc. Due to the presence of gum, the fibre becomes stiff and brittle. It acts as an inhibitor for water and other chemicals to enter inside the fibre. So, it is always better to remove the gum content of ramie fibre before going for the processing of the fibre.
The process of removal of gum from the fibre is known as degumming. Degumming can be done with chemicals like sodium hydroxide 13 , 14 or with enzymes 15 - 19 or with microbial action The tenacity, wet strength, extensibility are increases. Removal of the gum enables the fibre to take a more crystalline form. On gum removal, the crystallites increase in width but deteriorate with regard to their alignment along the fibre axis The ribbons of ramie, on their arrival at the factory, are greenish yellow to yellowish-white strips.
They may be used in this form for coarse products, but if ramie is to be spun into yarns suitable for fine fabrics, the first process in the mill is to degum the ribbons. Generally caustic soda is used for degumming process. The gums of ramie are composed of araban and xylans which are insoluble in water but easily soluble in alkaline solutions.
A slight mistake in the degumming process can spoil the quality of fibre, since the major component in ramie is cellulose and is sensitive to alkali.
It is essential to remove the excess of alkali by acetic acid treatment after chemical degumming, otherwise the fibre strength will be reduced. After the fibre has been submitted to the degumming action, it is thoroughly washed and dried.
The separated cells of ramie, known as "filasse" although white and clean, are still somewhat harsh and dry. In order that the fiber may lend itself more readily to the subsequent manufacturing operations, it is usually treated with an oily preparation composed in most cases of water, glycerine, wax and soap, when it is thoroughly softened, ramie is ready for processing The SEM images showing the effect of combined degumming and bleaching is shown in Fig. From the figure it is observed that after the chemical treatment, the fibres are found to be clean.
In a study the degumming of ramie with sodium metasilicate, alone or in combination with other alkali solutions such as sodium carbonate, trisodium phosphate and sodium metasilicate phosphate, has been reported The most significant factors involved in ramie degumming are the concentration of the chemicals, temperature, time and the methods employed to ensure that the degumming liquor penetrates to all parts of the ribbons. The decorticated and chemically degummed fibres are as shown in Fig.
There is no international grading system is available for grading of ramie fibre and the grading is done as per the standards developed by the ramie producing countries. Ramie fibre will be graded before taken in to processing industry. The existing jute grading system can also be adoptable in the case of ramie.
Generally two methods of grading are adopted. Hand and eye method and instrumental method. During grading, the following parameters are to be checked. Colour, strength, softness, length, fibre separation and defects major, minor. The market prize of ramie fibre is determined by grading system. Ramie is a unicellular cellulosic bast fibre. Among all the bast fibres, major content of cellulose is found in the ramie.
Ramie fibre comes under bast fibre category, which can be classified as underutilised fibres. The high potential of ramie fibre is not fully exploited due to various techno-economic reasons. It is one of the strongest natural fibres having rich cellulose content. Apart from textile uses, ramie fibre can be utilised for the production of various diversified products. Still in present scenario, there is much scope for research and development on this valuable fibre. This study briefs the extraction, mechanical processing, fibre properties and value addition of ramie fibre.
Fiber Selection for the Production of Nonwovens
Account Options Sign in. My library Help Advanced Book Search. View eBook. Chemistry of the Textiles Industry. The manufacture and processing of textiles is a complex and essential industry requiring many diverse skills to ensure profitability.
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Many of us tend to believe that natural fibres, being products of nature, are naturally better than their synthetic counterparts. However, this isn't always the case. The production of most natural fibres such as cotton, wool and silk have their fair share of environmental and ethical issues too - it's just that 'natural' is often associated with 'good'. Although the impact on the environment, workers and animals or plants involved in the production varies for each fibre, the impacts nevertheless exist. The production process of non-organic cotton, for instance, is chemical-intense and this extensive use of toxic agents has been linked to severe health problems in farmers who grow it amongst a plethora of other environmental and social atrocities. Cotton is not alone here - every natural fibre has a background story that deserves attention for anyone who has concerns around human and environmental health. Commercial cotton is chemical-intensive. Support farmers' health - go organic - OffsetWarehouse. Join me, as I go into the details of various environmental and ethical issues that are part of the very first stages of production of natural fibres like cotton, wool and silk. Cotton farming involves large quantities of chemicals in the form of pesticides, insecticides, herbicides and fertilisers.
Materials & Technologies
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Learn More:. Some of the tree-related facts with regard to viscose rayon are chilling--while cotton plants are replaced seasonally on the farm, pine trees, for example, take years to regenerate after harvesting for viscose rayon. Furthermore, nearly 30 percent of the viscose rayon used in the fashion industry are harvested from ancient and endangered forests worldwide. The harvested trees go through a harsh chemical process to remove everything bark, lignin, etc. Both of these molecular qualities combine to make cotton fiber much stronger than rayon fiber. The same two molecular properties also lead to the amazing fact that cotton fibers increase in strength when wet, whereas viscose rayon fibers lose strength when wet. Improved wet strength is important for nonwovens like dry wipes that are used to absorb spills, and also for added strength in pre-moistened wet wipes. Higher wet strength is also an asset for medical products that are used to clean and protect, absorb bodily fluids, and even to support organs during surgery.
Ramie Fibre Processing and Value Addition
The most significant feature of nonwoven fabric is made directly from fibers in a continuous production line. While manufacturing nonwovens, some conventional textile operations, such as carding, drawing, roving, spinning, weaving or knitting, are partially or completely eliminated. For this reason the choice of fiber is very important for nonwoven manufacturers. The commonly used fibers include natural fibers cotton, jute, flax, wool , synthetic fibers polyester PES , polypropylene PP , polyamide, rayon , special fibers glass, carbon, nanofiber, bi-component, superabsorbent fibers. Raw materials have not only delivered significant product improvements but also benefited people using these products by providing hygiene and comfort. Non-woven Fabrics. However, today, the nonwoven fabric technology is the most modern method used in the branch of textile industry. Nonwoven technology exists to approximate the appearance, texture, and strength of conventional woven and knitted fabrics due to their simple production stages, high efficiency of production, lower cost, and disposability.
Fiber Selection for the Production of Nonwovens
There are many reasons in favor of our cellulose fibers from the renewable raw material wood. Consumers can be pleased to get an aesthetically looking garment with high wearing comfort or a hygiene product with high absorbancy — all without having a bad conscience when it comes to nature. First of all, Lenzing fibers boast ecological benefits such as low water consumption over the life cycle and the fact that they compete to a low extent for agricultural land required for the production of food. This is frequently the case with cotton plantations. Forest areas usually do not compete with areas under cultivation for food, and do not require artificial irrigation. In this way, the sustainable raw material cycle of our fibers is closed. Natural cellulose is also the main reason why products made of Lenzing fibers boast such a high level of wearing comfort. They are effective in absorbing moisture from the human body and are perceived as soft and supple.
The products and brands we make at our facilities around the world intersect with your daily life, even though you may not always notice them. This includes the polymers, fibers and resins we make, as well as the brands, trademarks and innovations we take to market for the benefit of everyone. Since the s, nylon has become an essential part of everyday life. As a versatile thermoplastic, nylon 6,6 can be melted and shaped to serve many applications, from heat-resistant auto parts to consumer electronics and kitchen appliances.
Natural fibers have been used as an alternative to synthetic ones for their greener character; banana fibers have the advantage of coming from an agricultural residue. Fibers have been extracted by mechanical means from banana tree pseudostems, as a strategy to valorize banana crops residues.
Fiber or fibre in British English , see spelling differences ; from the Latin fibra  is a natural or synthetic substance that is significantly longer than it is wide. The strongest engineering materials often incorporate fibers, for example carbon fiber and ultra-high-molecular-weight polyethylene. Synthetic fibers can often be produced very cheaply and in large amounts compared to natural fibers, but for clothing natural fibers can give some benefits, such as comfort, over their synthetic counterparts.