The consumption of these fibres by this vast 2 Bast and other plant fibres industry is therefore limited to their lower qualities. These developing countries naturally add as much value as they can to their raw material production by spinning, weaving and sometimes making finished consumer products from their fibres.
Several interesting examples of such developments are described by the authors of Chapter 2 on jute but since there are at least to the knowledge of this editor no effective marketing organisations capable of testing markets, promoting the products and arranging appropriate prices and distribution, very little actual new product marketing occurs. In other industrial sectors this is usually done by the market leaders or well financed newcomers to the markets but in the textile manufacturing industry in general there rarely are any market leaders. Even the larger companies are often family businesses and generally too small to be able to ensure financial margins that are sufficient to cover the costs of such market development operations.
The only real solution for these small and medium sized enterprises is to cooperate, establish and collectively fund such market development organisations, perhaps with the help of governments or regional or global development banks. This seems obvious but it is, in fact, difficult; especially as most of these fibres are produced in Asian countries which have, at least as far as family companies are concerned, fiercely individualistic cultures.
But it is difficult to see any other solution to this problem; but solution there must be if these industries are to progress into the 21st century. They are therefore competitors and in an ideal world it could be thought useful, Overview 3 in a book of this kind, to provide comparisons between their prices. For example, the case of flax again Chapter 3 , the price of line can be, and often is, ten times higher than that of tow. It is therefore necessary, when wishing to compare prices, to be specific concerning dates, currencies and qualities.
The statistics on fibre prices that are available for some of these fibres specify which quality of the fibre is concerned, and often its country of origin. This, although useful, gives only a limited view of the total market. Nonetheless, these statistics cannot be more accurate than the figures that are supplied to them by the many countries involved and it does seem that from time to time some inaccuracies creep into the system. These could be due to double counting or by the inaccuracy of the input figures but, should any doubt arise, it is advisable to check directly with the FAO and possibly with other independent sources.
Also, it will be seen from some of the tables that different sources often give different values for the physical and chemical characteristics of the fibres. The reason behind these seeming differences is that we are dealing with natural, growing, organisms that are not uniform in their compositions or properties.
The fibres may have been obtained from different varieties of the same plant species, the tests may have been carried out at different stages of maturity of the plants and by using different methods of analysis or testing, the plants from which the fibres were extracted may, and probably did, grow in different soils and under different meteorological conditions. Therefore it is to 4 Bast and other plant fibres be expected that the test results are not likely to be identical.
By offering our readers the results obtained from different sources we are able to illustrate the variation that exists in this field. Table 1. Note that the cellulosic microfibrils of bast fibres impart enormous tensile strength at best similar to Kevlar , and the lignin content gives rigidity and a degree of hydrophobia. This table gives certain other physical characteristics of several natural fibres compared to certain manufactured high-performance fibres. Marsh's classic textbook on Textile Science, first published in , we find the dimensions of ultimate fibres shown in Table 1.
Overview 5 Table 1. Overview 11 Table 1. From: www. However, low specific gravity results in a higher specific strength and stiffness than glass. This is a benefit especially in parts designed for bending stiffness. In addition, the natural fibres offer good thermal and acoustic insulation properties along with ease in processing technique without wearing of tools. Biswas, G. Srikanth and S. Overview 15 Table 1. Source: Batra, S.
Lewin and E. Courtesy: J. Note: Immature fibres, very thin cell wall and few convolutions. Ramie raw, before degumming Fibre bundles with cross-markings, longitudinal and transverse fissures. Flax raw Fibre bundles, cross-markings, nodes, fissures, but otherwise smooth. Jute raw Fibre bundles, very rarely cross-markings, nodes or fissures; ultimate fibres bleached or macerated with lumen considerably varying in size along the same fibre Cross-section Kidney and bean-shaped, seldom round or oval; lumen as a line or oval.
Most fibres round or oval number depending on degree of mercerisation ; very small or no lumen. Bundles and possibly some individual fibres. Elongated polygons, often with curved side-lines, and sometinmes rounded; thick wall, radial fissures; lumen long and narrow or same shape as fibre section. Shape and size of the fibre bundles partly depending onpreparation; ultimate fibres mainly sharply polygonal with narrow, round or oval lumen; also rounded oblong forms with larger lumen.
Similar to flax; lumen often as a mere line and indistinct Fibre bundles of varying size; ultimate fibres mainly sharply polygonal, some with rounded corners; lumen round to ovbal with very varying size Adapted from Luniak, B. Overview 19 Table 1. Adapted from Luniak, B. Overview 1. Chum, Helena L. Chawle, K. Dippon, K. Oktober Faserinstitut Bremen.
Dreyer, J. Eddlestone, E. Herzog, R. Jarman, C. Lewin, M. In Handbook of Fiber Science and Technology. Volumne IV. Marcel Dekker, Inc. Liebscher, U. In Technische Textilien, 26, 1, pp. Quoted in Koch, P. Luniak, B. Melliand Textilberichte, 36, August, pp. Marsh, J. Mondenschein, S. Nathanael, W. Triolo, L. In Italia Agricola, 1, pp. Abaca Musa textilis is not included as the fibre is obtained from the leaf sheath of the plant and is therefore not a bast fibre.
There are over thirty Corchorus species but only two of them are widely known, Corchorus capsularis white jute and Corchorus olitorius tossa jute These are commercially grown in Bangladesh, India and Nepal. Kenaf and mesta rosella or roselle , the other fibres allied to jute, are grown in China and Thailand.
Mesta is also grown and is commercially important in India and Thailand. White and tossa jute cannot normally tolerate water-logged conditions but can be grown on high land that is normally subject to flooding. Jute is mainly used for manufacturing products for the packaging of grains, sugar, cocoa, coffee and other food crops as well as for cement, fertilisers, salt, cotton, etc.
These, i. Area ' hectares Production ' tons XIII, No. Other uses of jute include carpet yarn, cordage, felts and paddings, decorative fabrics and other items for industrial use. Raw jute production was originally concentrated in eastern Bengal which, after the partition of the Indian Sub-continent in , became East Pakistan and later in became an independent country, Bangladesh. After partition measures were taken in India to increase the production of raw jute in order to supply raw material to its jute mills.
Although jute has been an economically2 important crop in Bangladesh and India it has, to some extent, lost its past importance in the economy of these countries, although it still has a high socio-economic value. As an important cash crop of the region it contributes to the economy of these countries in various ways. In agriculture as well as in industry, in both these countries, jute directly and indirectly supports employment, commerce and other economic activities. There are 76 jute mills in India with installed capacity of 45, looms and in Bangladesh there are 72 jute mills with installed capacity of 26, looms.
However, in Bangladesh and India about four million farm families cultivate jute as an important cash crop. In India, the jute industry provides employment for about 2. This does not include the ten million hand loom weavers mentioned in Sections 5. In Bangladesh about , workers and 25, management and staff are employed in the jute industry. Allied trades, industries and services such as marketing, transportation, etc. Jute and jute products occupy an important place as a foreign exchange earner, particularly in the case of Bangladesh. Prior to independence jute was the principal source of Pakistan's foreign exchange.
Jute is also a source of revenue for the Governments of India and Bangladesh. The Indian government receives annually more than Rs. World apparent consumption of jute, kenaf and allied fibres1 is given in Table 2. According to the available statistics, world production of jute goods works out to about three million m tonnes Table 2.
Some countries, especially India, export fibre as well as jute goods. This shows as a lower figure in the tonnage of their apparent consumption and of jute goods produced in these countries, compared to their production of fibre. Waste is produced in processing from fibre, through yarn to fabric and other jute goods, which will also show as a lower figure of goods manufactured compared to fibre produced. Jute 27 Table 2. In the production of jute goods jute fibre is sometimes blended with other fibres such as cotton, polyester, viscose, acrylic, etc.
This will appear in the statistics as an increase in the weight of goods manufactured when compared to fibre produced or apparently consumed. The present situation can be summarised as follows: production of jute fibre, Although over 40 wild species are known, only two, viz. Within the jute manufacturing industry, C. There are many plants similar to Corchorus that grow in the tropics and subtropics, and from which fibres can be extracted from the stem. The most important of these from the point of view of textile fibres are two species of the genus Hibiscus, viz.
Hibiscus species are more tolerant of variations in growing conditions than jute, and many countries, especially in Africa and Asia, grow kenaf as a preferred crop, usually for internal use only, the international market for Kenaf being quite small. A third plant of similar type, Urena lobata L.
All fibrebearing plants have their own distinctive botanical attributes, but the fibres extracted from them are markedly similar to one another in appearance and are not readily distinguishable from jute itself. Spinnable fibres are composed of ten or more ultimate fibres placed in overlapping fibre bundles joined together by noncellulosic material, usually lignin. Though jute is a strong fibre, its very low extensibility results in stiff, non-stretchy fabric. In developing countries, jute is much used for woven hessian, sacks, packaging and tarpaulins.
Figure 2. Source: Gesamtverband der Deutschen Versicherungswirtschaft. Courtesy: www. Jute 29 Figure 2. Source: C. Jarman, Plant fibre and processing: A handbook. The pure fibre content of the unretted plants lies between 4. About 90 to days after sowing the stems may be harvested and water retted.
Bast and Other Plant Fibres Edited by Robert R Franck
In the process the stems are carefully sorted according to thickness and the lower, very wooden part of the stalk is cut off. After retting the stems are decorticated and the fibre bundles are washed and dried. Kenaf is more lustrous, harder and stronger than jute and is lighter in colour. Kenaf is used to make rope and string, coarse fabrics, mats and carpets. The potential development of the use of jute and kenaf fibres in composite materials is discussed in Chapter Courtesy: Roger M.
With about the same stalk length of 2. After harvesting the stalks are retted. This must be done with great care if good quality fibres are to be obtained. This is required to eliminate the gummy substances which cement the fibre to the rest of the tissues in the stem, and to each other. In the case of jute and allied fibres this involves steeping the stems in water, where enzymes produced by bacterial action remove the pectin and gummy materials, after which the fibres can be stripped from the woody core.
The fibres are then washed and hung out to dry before being taken to the local market for sale to balers and exporters. Extraction of the fibres from the retted stalks decortication is, in the case of jute and similar fibres, still usually done manually Fig. Jute 31 Figure 2. Mechanical decorticators of the kind mentioned in section 2. In manual decortication the fibres are stripped from the woody core of the stem using knives. In the retting process, the thicker parts of the stem take longer to rett than the thinner parts. Consequently, if the butt end of the stem is correctly retted, the apex will be over-retted and may suffer damage.
The various factors affecting retting of jute and mesta are types of water, temperature, pH and macro-nutrients. Water appears to be the most important of the various factors affecting retting. An abundant supply of clean water is a prerequisite for proper retting. Retting in slow-flowing water produces the best fibre.
In faster, running water, retting is adversely affected. Retting is quicker in soft than in hard water and the colour and lustre of the fibre is remarkably improved by immersing the stack under water with bamboo poles and coir ropes. Concrete slabs as weights also give excellent results. Various chemicals, particularly nitrogen and phosphorous compounds, have been tried to boost the retting of jute and 32 Bast and other plant fibres nitrogenous compounds and have proved to be the best stimulants.
Conventional and ribbon retting: advantages and disadvantages In conventional retting, whole stems are steeped in water, but in ribbon retting only the ribbons of green bark extracted from the stems are immersed in water. These ribbons are removed from the stems after harvesting in the fields. From four to six stems are decorticated manually at the same time. This produces a ribbon-like bundle of long fibres whilst decorticating after the conventional retting process produces fibres of between 15 cm to 25 cm in length.
The quantity of water required for ribbon retting is much less than for the conventional method. Ribboning of an entire jute stem is not possible; some of the bark always remains on the stem, especially at the top of the stalks. Any ageing of harvested stems further aggravates this loss of bark on ribboning because a certain amount of fibre always remains stuck to the bark.
During the vegetative growth phase, jute plants may be attacked by insects, apion in particular, and it has been found that apion infected jute stems also entail an additional loss of bark during ribboning. Besides, the amount of labour involved in the whole process of ribboning is really forbidding. About one man day is required to ribbon three bundles of jute stems, which yields only 6.
On the other hand, transport costs are lower for ribbon retted fibre, retting takes less time, fibre quality is improved, pollution is much reduced and less water is required in comparison with conventionally retted fibre. The comparison between stem and ribbon retting is shown in Table 2. The machine is designed to extract and scrape out barky material from the stems of bast fibre crops such as jute, mesta, sunnhemp, urena, etc.
The machine breaks down the inner woody cores of the stems into pieces and scrapes the bark, especially at the root ends of the stalks. The production of commercial fibres by Jute 33 Table 2. Criteria Stem retting Procedure Ribbon retting 1. Quality of sticks Long sticks obtained, With decorticator use, sticks are easy to handle, broken. Ribboners yield long sticks structural uses possible 8.
Plant nutrient loss Large qualities removed Returned to soil if the cores are with stalks incorporated to the soil 9. The capacity of the machine is about a tonne of green jute plants per hour with a 5 hp primemover. Five men are needed to operate the machine, two for feeding stems into the machine and three for arranging, bundling and steeping of the extracted material.
If required the capacity of this machine can be increased. Decortication should be done immediately after harvesting and can be continued for two to three days if the stalks are kept under cover. Defoliation is not necessary before feeding the stems into the machine. The plants are fed into the machine butt-end first.
Two to eight plants are fed into the machine at a time, depending upon their diameter. It has been found that the optimum diameter for decortication by these machines is around 12 mm. According to Rowell and Stout91 the classification of fibres still takes place using organoleptic methods but as the classification systems are different in each country international comparison is difficult. They have a high initial modulus, but show very little recoverable elasticity.
Tenacity measurements recorded in the literature vary widely, and although some of this variation is due to differences in the methods of measurement, a major part arises from variation in linear density of the fibres themselves. This value of tenacity is appropriate to fibres of linear density 1. This inverse dependence of tenacity on linear density is common to most fibres and also to fine metal wires.
The elongation at which a fibre breaks is a more invariant and fundamental property than the load at which it breaks.
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It is not affected significantly by changes in linear density, nor by changes in the method of loading. Length of test specimens does have an effect, however, as irregularities in diameter prevent all sections of a long fibre from being elongated equally. In one particular case, fibres from a bulk of medium-quality jute had a mean elongation of 1.
It may be noted that 1. The value for any particular group of fibres will, of course, be dependent on the linear density, to some extent owing to the dependence of tenacity values on this factor. The bending of jute fibres has been studied by Kabir and Saha, who calculated the Young's modulus from measurements of the force required to deflect the free ends of a fringe of fibres arranged in cantilever fashion.
The authors assumed an elliptical configuration and measured minimum and maximum diameters of a number of cross-sections microscopically for insertion in the appropriate formula. Their calculations showed that over a wide range of commercial fibre qualities, Young's modulus decreased from about 2. Young's modulus may also be calculated from the fundamental frequency of transverse vibration of a single fibre fixed at one end as a cantilever. The extent of the difference between the two frequencies gives an indication of the departure from a circular outline. Kabir and Saha also examined the effect of delignification on the bending modulus of jute, using the fringe technique, and showed that successive extractions of lignin on the same fibres resulted in increasing flexibility and decreasing Young's modulus.
At the same time, however, the diameter of the fibres was reduced significantly and this may have affected the flexibility. Physical properties of jute fibres are set out in Table 2. Property White jute Tossa jute Roselle 1. Natural fibres lose strength when buried in the ground due to the growth of microorganisms. The micro-organisms play a predominant role in the degradation of fibre cellulose by the secretion of enzyme cellulose, the ultimate result of which was the loss in tenacity values Table 2.go
Bast and Other Plant Fibres - Book - Read Online
Alpha cellulose forms the bulk of the ultimate cell walls with the molecular chains lying broadly parallel to the direction of the fibre axis. The hemicellulose and lignin, however, are located mainly in the areas between neighbouring cells, where they form the cementing material of the middle lamella, providing strong lateral adhesion between the ultimates. The precise nature of the linkages that exist between the three components and the role played by the middle lamella in determining the fibre properties are incompletely understood.
Professor Lewin,21 some years ago, in an interesting Jute 37 literature survey on the middle lamella of bast fibre, brought together a great deal of relevant information that illuminated many of the problems but a thorough understanding of the intercell structure is still awaited. X-ray diffraction patterns show the basic cellulose crystal structure but in jute and kenaf, although the crystallite orientation is high, the degree of lateral order is relatively low in comparison with flax. There is also considerable background xray scattering arising from the noncellulosic content of the fibre.
The cellulosic molecular chains in the secondary walls of ultimate cells lie in a spiral around the fibre axis. The effect of this is to produce double spots in the x-ray diffraction patterns, the centres of the spots being separated by an angular distance of twice the Bragg angle. For large angles, such as occur in coir fibre and some leaf fibres such as Mauritius hemp, the two spots are visibly separated but for the small angles found in jute and kenaf, the spots overlap.
In this case the distribution of intensity across the width of the spots, instead of reaching a peak at the centre of each, is spread out into a single flatter, peak. The  equatorial reflection shows these effects particularly well and analysis of the intensity distribution allows calculation of the Herman's RMS spiral angle. The leaf fibres in this study are particularly interesting because as well as covering a good range of spiral angles, they also cover a wide range of ultimate cell dimensions.
The results indicate that among this group of fibres, the spiral structure averages a constant number of turns per unit length of cell, about ten per millimetre, and with this arrangement in the spiral angle then depends solely on the breadth of the cell. Whether this constancy of turns applies to individual cells, or whether as in wood, the longer cells tend to have steeper spirals, was not, however, investigated. For the secondary bast fibres, the cell dimensions show little variation between plant species, but the number of spiral turns per unit length of cell averages only about four per millimetre, appreciably less than for the leaf fibres.
The importance of the spiral angle measurements lies in the control that the spiral structure exercises on the extension which the fibre can withstand before breaking. The lignin can be almost completely removed by chlorination methods in which a soluble chloro-lignin complex is formed and the hemicellulose then dissolved out of the remaining holocellulose 38 Bast and other plant fibres by treatment with dilute alkali.
The final insoluble residue is the alpha-cellulose constituent, which invariably contains traces of sugar residues other than glucose. The hemicellulose consists of polysaccharides of comparatively low molecular weight built up from hexoses, pentoses and uronic acid residues. In jute, capsularis and olitorius have similar analyses, although small differences occur between different fibre samples. For fibre extracted from jute plants grown in Bangladesh, the range of composition has been given as lignin All percentages refer to the weight of dry fibre.
As well as the three principal constituents, jute contains minor constituents such as fats and waxes 0. The detailed molecular structure of the hemicellulose component is not known with certainty, although in the isolated material the major part is stated24 to consist of a straight chain of D-xylose residues, with two side branches of D-xylose residues, whose position and length are uncertain.
In addition there are other side branches formed from single residues of methyl glucoronic acid, to the extent of one for every seven xylose units. The third major constituent, lignin, is a long-chain substance of high molecular weight which, like hemicellulose, varies in composition from one type of vegetable material to another. The molecular chains are built up from comparatively simple organic units that may differ from different sources, and also in the way in which they are combined. Most of the studies in lignin have been concerned with wood and the bast fibres have been rather neglected.
It seems unlikely, however, any major differences will exist between jute and wood lignin, but in any case many details of the molecular structure still remain unresolved. Jute 39 Figure 2. In addition to fragmentation, the pins of the breaker card have a cleaning action by removing loosely adhering non-fibrous matter from the fibre proper. Sliver quality Sliver from the breaker card is then passed through the second, or finisher card, which causes a little more fibre breakage and provides further opportunity for removal of non-fibrous matter.
In addition, the finisher card has an important mixing effect, since a number of slivers are fed to the card in parallel and emerge finally as a single sliver. The quality parameters for the unevenness for carded sliver29 are given in Table 2. In the three drawing stages, the movement of fibre is controlled by gill pins fixed to faller bars. In modern drawing frames, the faller bars move on spiral screws, although some spinners prefer the push-bar method for the first stage.
At all stages, drafting is accompanied by appropriate doubling of the input slivers. The quality parameters for the unevenness of drawn slivers29 at the drawing stages are shown in Table 2. The output sliver from the final drawing stage then passes to the spinning frame, where its linear density is reduced suitably for the yarn being spun, after which the required twist is inserted. Almost universally in the jute industry, the insertion of twist is performed by overhung flyer, with the yarn winding-on to a bobbin rotating on a dead spindle, against a friction drag. Other methods of inserting twist by ring or pot-spinning are available but are little used, and then only for yarns of higher linear density.
Prior to the late s, jute yarn was mainly spun from rove, the output sliver from the third stage of drawing being given a small twist to hold the fibres Table 2. MR: Moisture regain 42 Bast and other plant fibres together for transport to the spinning frame. Production of rove in this way was a slow process, however, and during the s spinning from rove was superseded by spinning directly from third-drawing sliver. To hold the fibres together, the sliver is passed into a crimping box, which gives it a small crimp. This is just as effective as twist but is a much faster process. Specifications for sale yarn quality parameters are shown in Tables 2.
The yarn runs loosely behind the plate instead of being fixed in position as previously, when wrapped round a flyer leg. Compared to the two-legged flyer, the rigid flyer results in reduced yarn tension and also permits the use of larger bobbins. In commercial spinning it is interesting to note that using similar good quality fibre, the spinning limit of a slip-draft frame fitted with two-legged flyers is commonly taken to be about tex, whereas the combination of apron-draft and rigid flyer increase the fineness of the yarn to about tex.
Table 2. This machine automatically adjusts the draft according to the thickness of the output sliver and thereby maintains a more uniform linear density of sliver than is normally obtained with fixed-draft machines. It is only on long lengths of yarn that levelness is improved, of course, the short-term levelness being virtually unaffected. Careful preparation of fibre before presentation to the breaker card is necessary if the best results are to be obtained from the spinning system.
Application of water, to soften the fibre, and oil, to lubricate it, is essential, except where oil is undesirable for a particular end-use, in which case a non-oily lubricant must be used. The liquids are usually applied in the form of an oil-inwater emulsion, the composition and rate of application being controlled to give the desired add-on of both water and oil.
If the breaker card is to be hand-fed with long jute, the lengths of fibre are first passed through a series of heavy fluted rollers on a jute softener, a machine that is also used for preparing cuttings. If, however, the breaker card is to be fed from rolls of fibre, a jute spreader is used to form the rolls. This is similar to the goods machine used in the hard-fibre industry, and emulsion application takes place through either softener or spreader.
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High speed ring-spinning machines for spinning fine jute yarns are manufactured by Lummus Mackie, UK and N. Schlumberger, France. Also SITRA have developed a low-cost spinning machine for fine-count jute yarns but these have not yet been taken up by the industry due to the lack of demand for such yarns. Jute 45 Figure 2. The process flowchart for producing fine jute yarn is given in Fig.
The quality characteristics of fine jute yarn and jute blended yarns produced by using imported machines are given in Table 2. All jute combed yarn ii 3 lb. These blended yarns were used to manufacture a wide range of sample fabrics including curtain fabrics, blankets, bedspreads, floormats, industrial fabrics, pile fabrics and others.
Due to their warmth-retention property, acrylic fibres are frequently used as a substitute for wool for use in cooler climates. In this context, blending a small proportion of jute with acrylics may have cost advantages without significantly affecting the warmth-retention property of the fabric. Such yarns could be woven on Table 2.
Some of the products made from such yarns include: denim on shuttle less looms; curtain fabrics and shawls on handlooms; and niwar a narrow fabric on tape looms. Lakshmi Machine Works Ltd. The core jute yarn provides the necessary strength and the sheath of staple fibres provide the necessary comfort and aesthetic appeal for manufacturing products such as blankets, dhurries a heavy floor covering fabric and furnishings. Jute 49 Upgrading of jute fibres Many attempts have been made to improve the spinning quality of jute by the action of enzymes and other bio-agents. Enzymes start their bio-chemical reactions in the presence of moisture on the substrates that are specific to the enzyme involved, i.
These enzymes are called hydrolases as they catalyse the hydrolic degradation of specific carbohydrates. These simultaneous actions are the hydrolic degradation of the tissues of the plants which requires moisture and the bacterial action, which is accelerated by the easily assimilable reaction products generated by enzymic action. The synergistic effect of the two biological systems results in both softening and upgrading the jute fibres.
Although the average filament strength of enzyme treated jute is more or less the same as that of untreated jute the quality ratio values of the treated yarns are higher than those of the untreated yarns. This is due to the fact that the enzyme and bacteria treated fibres build up to a more compact yarn. Another interesting effect of the enzyme treatment of jute fibres is the increase in equilibrium moisture regain of the treated fibres.
A higher moisture retention property ensures improved spinnability of the treated fibres, even under dry atmospheric conditions. Spinning assistants Jute fibres have a low natural content of fats and waxes and some added lubrication is essential for good yarn regularity. Mineral oil is the commonly used lubricant, applied as an emulsion in water. The amount added ranges between 0. Mineral oils are absorbed to some extent into the body of the fibre through crevices in the surface and internal holes.
Bast and Other Plant Fibres
Low-viscosity oils are absorbed rapidly and leave the surface relatively oil free, in a state corresponding to boundary-lubrication conditions. High-viscosity oils, on the other hand, are absorbed more slowly into the fibre and mainly remain on the surface, and so produce the appropriate conditions for hydrodynamic lubrication. This is due to increased friction between the fibres on removal of the oil, which helps to prevent slippage before the fibres break and thus enables them to achieve a higher breaking load. It would be expected that a similar effect would result from the addition of a friction-increasing substance, such as colloidal silica and this is indeed the case.
As with scouring, the silica prevents fibre slippage and produces more breakage. Moreover, when the fibres do break, rather than slip, the elongation of the yarn increases slightly. Friction requirements In a perfect yarn, where the fibres are arranged entirely at random, the PMD value will be inversely proportional to the square root of the number of fibres in the cross-section. Actual PMD values are always greater because the fibres draft not as individuals, but in groups. This results in a succession of thick and thin places along the length of the yarn.
There are two opposing factors, the cohesion of the slivers being drafted and the restraint offered by the pressure of the gill pins on the faller bars. The overall effect will be for the groups of fibres to be broken up, which leads to greater regularity. Similar frictional effects have been study by Spencer-Smith and Todd25 for long staple manmade fibres on flax-spinning systems. These authors concluded that the ratio of the coefficient of static friction between fibres to the corresponding coefficient of static friction of fibres on steel should be as small as possible to spin the most regular yarns.
Other factors, such as gill-spacing and fibre-loading on the drawing frames also affect yarn regularity, but in addition to the purely frictional effects. Although mineral oils are in common use as inexpensive lubricants many chemical manufacturers supply proprietary additives of an organic chemical nature, which confer Jute 51 particular surface properties on fibres.
Such additives are commonly long-chain fatty acids or alcohols, condensed with ethylene oxide molecules. In addition, various wax dispersions are available and although all these non-oily materials are more expensive than mineral oil, the importance of achieving the correct surface properties of fibres by using a proper choice of lubricant is an important factor in spinning the highest quality yarns.
Chemical and physical fibre structure. Bleaching dyeing printing and finishing. Products and applications. Handle and wear characteristics. Part 2. It is necessary to also consider other fibers such as ones made from seed coir and animals chicken feather as they are secondary or made from waste products. Few plant fibers such as bast fibers are often reviewed briefly but other plant and animal fibers are not discussed in detail.
This review paper discusses all the six types of plant fibers such as bast, leaf, seed, straw, grass, and wood, together with animal fibers and regenerated cellulose fibers. Additionally, the review considers developments dealing with natural fibers and their composites. The fiber source, extraction, availability, type, composition, and mechanical properties are discussed.
The advantages and disadvantages of using each biofiber are discussed. Three fabric architectures such as nonwoven, woven and knitted have been briefly discussed. Finally, the paper presents the overview of the results from the composites made from each fiber with suitable references for in-depth studies. Skip to Main Content. Search in: This Journal Anywhere.
Advanced search. Journal Polymer Reviews Volume 55, - Issue 1. Submit an article Journal homepage. Skrifvars hb. Pages Received 14 May