FIBRES, the general term for certain structural components of animal and vegetable tissue utilized in manufactures, and in respect of such uses, divided for the sake of classification into textile, paper-making, brush and miscellaneous fibres.
The common characteristics of the various forms of matter comprised in the widely diversified groups of textile fibres are those of the colloids. Colloidal matter is intrinsically devoid of structure, and in the mass may be regarded as homogeneous; whereas crystalline matter in its proximate forms assumes definite and specific shapes which express a complex of internal stresses. The properties of matter which condition its adaptation to struc tural functions, first as a constituent of a living individual, and afterwards as a textile fibre, are homogeneous continuity of sub stance, with a high degree of interior cohesion, and associated with an irreducible minimum of elasticity or extensibility. The colloids show an infinite diversity of variations in these essential properties: certain of them, and notably cellulose (q.v.), maintain these characteristics throughout a cycle of transformations such as permit of their being brought into a soluble plastic form, in which condition they may be drawn into filaments in continuous length. The artificial silks or lustra-celluloses or rayons are pro duced in this way, and have already taken an established position as staple textiles. For a more detailed account of these products see CELLULOSE and SYNTHETIC FIBRES.
The animal fibres are composed of nitrogenous colloids of which the typical representatives are the albumens, fibrines and gela tines. They are of highly complex constitution and their char acteristics have only been generally investigated. The vegetable fibre substances are celluloses and derivatives of celluloses, also typically colloidal bodies. The broad distinction between the two groups is chiefly evident in their relationship to alkalis. The former group are attacked, resolved and finally dissolved, under conditions of action by no means severe. The celluloses, on the other hand, and theref ore the vegetable fibres, are extraordinarily resistant to the action of alkalis.
The animal fibres are relatively few in number but of great industrial importance. They occur as detached units and are of varying dimensions; sheep's wool having lengths up to 36in., the fleeces being shorn for textile uses at lengths of 2 to I bin. ; horse hair is used in lengths of 4 to 24in., whereas the silks may be considered as being produced in continuous length, "reeled silks" having lengths measured in hundreds of yards, but "spun silks" are composed of silk fibres purposely broken up into short lengths.
The vegetable fibres are extremely numerous and of very di versified characteristics. They are individualized units only in the case of seed hairs, of which cotton is by far the most important ; with this exception they are elaborated as more or less complex aggregates. The bast tissues of dicotyledonous annuals furnish such staple materials as flax, hemp, rhea or ramie and jute. The bast occurs in a peripheral zone, external to the wood and beneath the cortex, and is mechanically separated from the stem, usually after steeping, followed by drying.
The commercial forms of these fibres are elongated filaments composed of the elementary bast cells (ultimate fibres) aggregated into bundles. The number of these bundles, of any part of the filament may vary from 3 to 20. In the processes of refinement preparatory to the spinning (hackling, scutching) and in the spinning process itself, the fibre-bundles are more or less subdi vided, and the divisibility of the bundles is an element in the textile value of the raw material. But the value of the material is rather determined by the length of the ultimate fibres (for, al though not the spinning unit, the tensile strength of the yarn is ultimately limited by the cohesion of these fibres), qualified by the important factor of uniformity.
Thus, the ultimate fibre of flax has a length of 25 to 3 5mm. ; jute, on the other hand, 2 to 3mm. ; and this disparity is an essen tial condition of the difference of values of these fibres. Rhea or ramie, to cite another typical instance, has an ultimate fibre of extraordinary length, but of equally conspicuous variability, viz., from 5o to 200mm. The variability is a serious impediment in the preparation of the material for spinning and this defect, to gether with low drawing or spinning quality, limits the applica tions of this fibre to the lower counts or grades of yarn.
The monocotyledons yield still more complex fibre aggregates, which are the fibro-vascular bundles of leaves and stems. These complex structures as a class do not yield to the mechanical treat ment by which the bast fibres are subdivided, nor is there any true spinning quality such as is conditioned by bringing the ulti mate fibres into play under the drawing process, which imme diately precedes the twisting into yarn. Such materials are there fore only used for the coarsest textiles, such as string or rope. An exception to be noted in passing is to be found in the pine apple (Ananas Sativus) the fibres of which are worked into yarns and cloth of the finest quality. The more important fibres of this class are manila, sisal, phormium. A heterogeneous mass of still more complex fibre aggregates, in many cases the entire stem (cereal straws, esparto), in addition to being used in plaited form, e.g., in hats, chairs, mats, constitute the staple raw material for paper manufacturers, requiring a severe chemical treatment for the separation of the ultimate fibres.
In this class we must include the woods which furnish wood pulps of various classes and grades. Chemical processes of two types (a) acid and (b) alkaline, are also employed in resolving the wood, and the resolution not only effects a complete isolation of the wood cells, but, by attacking the hydrolysable constituents of the wood substance (lignocellulose), the cells are obtained in the form of cellulose. These cellulose pulps are known in com merce as "sulphite pulps" and "soda pulps" respectively. In ad dition to these raw materials or "half stuffs" the paper-maker employs the rejecta of the vegetable and textile industries, scutch ing, spinning and cloth wastes of all kinds, which are treated by chemical (boiling) and mechanical means (beating) to separate the ultimate fibres and reduce them to the suitable dimensions (0.5-2.0mm.). These paper-making fibres have also to be reck oned with as textile raw materials, in view of a new and growing industry in "pulp yarns" (Papiersto ff garn), a coarse textile ob tained by treating paper as delivered in narrow strips from the paper machine ; the strips are reeled, dried to retain 30-40% moisture, and in this condition subjected to the twisting opera tion, which confers the cylindrical form and adds considerably to the strength of the fibrous strip. The following are the essential characteristics of the economically important fibres.
B. Epidermal hairs. Of these (a) wool, the epidermal protec tive covering of sheep, is the most important. The varying species of the animal produce wools of characteristic qualities, varying considerably in fineness, in length of staple, in composition and in spinning quality. Hence the classing of the fleeces or raw wool followed by the elaborate processes of selection, i.e., "sorting" and preparation, which precede the actual spinning or twisting of the yarn. These consist in entirely freeing the fibres and sorting them mechanically (combing, etc.) , thereafter forming them into con tinuous lengths of parallelized units. This is followed by the spinning process which consists in a simultaneous drawing and twisting, and a continuous production of the yarn with the struc tural characteristics of worsted yarns. The shorter staple—from 5 to 25% of average fleeces—is prepared by the "carding" proc ess for the spinning operation, in which drawing and twisting are simultaneous, the length spun being then wound up, and the process being consequently intermittent. This section of the in dustry is known as "woollen spinning" in contrast to the former or "worsted spinning." (b) An important group of raw material closely allied to the wools are the epidermal hairs of the Angora goat (mohair), the llama, alpaca. Owing to their form and the nature of the substance of which they are composed, they possess more lustre than the wools. They present structural differences from sheep wools which influence the processes by which they are prepared or spun, and the character of the yarns; but the dif ferences are only of subordinate moment. (c) Various animal hairs, such as those of the cow, camel and rabbit, are also em ployed ; the latter is largely worked into the class of fabrics known as felts. In these the hairs are compacted together by taking ad vantage of the peculiarity of structure which causes the imbrica tions of the surface. (d) Horse hair is employed in its natural form as an individual filament or monofil.
Vegetable Fibres.—The subjoined scheme of classification sets out the morphological structural characteristics of the vege table fibres:— Produced from Dicotyledons. Monocotyledons.
A. Seed hairs. D. Fibro-vascular bundles.
B. Bast fibres. E. Entire leaves and stems.
C. Bast aggregates.
In the list of the more important fibrous raw materials subjoined, the capital letter immediately following the name refers the indi vidual to its position in this classification. In reference to the important question of chemical composition and the actual nature of the fibre substance, it may be premised that the vegetable fibres are composed of cellulose, an important representative of the group of carbohydrates, of which the cotton fibre substance is the chemical prototype, mixed and combined with various deriva tives belonging to the subgroups. (a) Carbohydrates. (b) Unsat urated compounds of benzenoid and furfuroid constitutions. (c) "Fat and wax" derivatives, i.e., groups belonging to the fatty series, and of higher molecular dimensions—of such compound celluloses the following are the prototypes : (a) Cellulose combined and mixed with "pectic" bodies (i.e., pecto-celluloses), flax, rhea.
(b) Cellulose combined with unsaturated groups or ligno celluloses, jute and the woods.
(c) Cellulose combined and mixed with higher fatty acids, alcohols, ethers, cuto-celluloses, protective epidermal covering of leaves.
The letters a, b, c in the table below and following the capitals, which have reference to the structural basis of classification, indicate the main characteristics of the fibre substances. (See also CELLULOSE.) Miscellaneous Fibres.—Various species of the family Pal maceae yield fibrous products of value, of which mention must be made of the following. Raffia, epidermal strips of the leaves of Raphia ruffia (Madagascar), R. taedigera (Japan), largely em ployed as binder twine in horticulture, replacing the "bast" (lin den) formerly employed. Coir, the fibrous envelope of the fruit of the Cocos nuci f era, extensively used for matting and other coarse textiles. Carludovica palmata (Central America) yields the raw material for Panama hats, the Corypha Australis (Australia) yields a similar product. The leaves of the date palm, Phoenix dactyli f era, are employed in making baskets and mats, and the fibro-vascular bundles are isolated for working up into coarse twine and rope ; similarly, the leaves of the Elaeis guineensis, the fruit of which yields the "palm oil" of commerce, yield a fibre which finds employment locally for special purposes. Chamaerops hu'nilis, the dwarf palm, yields the well-known "Crin d'Afrique." Locally (Algiers) it is twisted into ropes, but its more general use, in Europe, is in upholstery as a stuffing material. The cereal straws are used in the form of plait in the making of hats and mats. Esparto grass is also used in the making of coarse mats.
The processes by which the fibres are transformed into textile fabrics are in the main determined by their structural features. The following are the distinctive types of treatment : A. The fibre is in virtually continuous lengths. The textile yarn is produced by assembling together the unit threads, which are wound together and suitably twisted (silk; artificial silk).
B. The fibres in the form of units of variable short dimensions are treated by more or less elaborate processes of scutching, hack ling, combing, with the aim of producing a mass of free parallel ized units of uniform dimensions; these are then laid together and drawn into continuous bands of sliver and roving, which are finally drawn and twisted into yarns. In this group are comprised the larger number of textile products, such as cotton, wool, flax and jute, and it also includes at the other extreme the production of coarse textiles, such as twine and rope.
C. The fibres of still shorter dimensions are treated in various ways for the production of a fabric in continuous length. The distinction of type of manufacturing processes in which the relatively short fibres are utilized, either as disintegrated units or comminuted long fibres, follows the lines of division into long and short fibres ; the long fibres are worked into yarns by various processes, whereas the shorter fibres are agglomerated by both dry and wet processes to felted tissues or felts. It is obvious, how ever, that these distinctions do not constitute rigid dividing lines. Thus the principles involved in felting are also applied in the ma nipulation of long fibre fabrics. For instance, woollen goods are closed or shrunk by milling, the web being subjected to a beating or hammering treatment in an apparatus known as "the stocks," or is continuously run through squeezing rollers, in weak alkaline liquids. Flax goods are "closed" by the process of beetling, a long continued process of hammering, under which the ultimate fibres are more of less subdivided, and at the same time welded or in corporated together. As already indicated, paper, which is a web composed of units of short dimensions produced by deposition from suspension in water and agglomerated by the interlacing of the component fibres in all planes within the mass, is a species of textile. Further, whereas the silks are mostly worked up in the extreme lengths of the cocoon, there are various systems of spin ning silk wastes of variable short lengths, which are similar to those required for spinning the fibres which occur naturally in the shorter lengths.
The fibres thus enumerated as commercially and industrially important have established themselves as the result of a struggle for survival, and each embodies typical features of utility. There are innumerable vegetable fibres, many of which are utilized in the locality or region of their production, but are not available for the highly specialized applications of modern competitive industry to qualify for which a very complex range of requirements has to be met. These include primarily the factors of production and transport summed up in cost of production, together with the question of regularity of supply ; structural characteristics, form and dimensions, including uniformity of ultimate unit and adapt ability to standard methods of preparing and spinning, together with tenacity and elasticity, lustre. Lastly, composition, which determines the degree of resistance to chemical disintegrating influences as well as subsidiary questions of colour and relation ship to colouring matters. The quest for new fibres, as well as modified methods of production of those already known, require critical investigation from the point of view of established prac tice. The present perspective outline of the group will be found to contain the elements of a grammar of the subject. But those who wish to pursue the matter will require to amplify this out lined picture by a study of the special treatises which deal with general principles, as well as the separate articles on the various fibres.
All animal fibres are effectively dissolved by 1o% solution of caustic potash or soda. The fabric or material is boiled in this solution for ten minutes and exhaustively washed. Any residue will be vegetable or cellulose fibre. It must not be forgotten that the chemical properties of the fibre substances are modified more or less by association in combination with colouring matters and mordants. These may, in many cases, be removed by treatments which do not seriously modify the fibre substances.
Wool is distinguished from silk by its relative resistance to the action of sulphuric acid. The cold concentrated acid rapidly dis solves silk as well as the vegetable fibres. The attack on wool is slow, and the epidermal scales of wool make their appearance. The true silks are distinguished from the wild silks by the action of concentrated hydrochloric acid in the cold, which reagent dis solves the former, but has only a slight effect on Tussore silk. After preliminary resolution by these group reagents, the fabric is subjected to microscopical analysis for the final identification of its component fibres (see H. Schlichter, Journal Soc. Chem. Ind., 189o, p. 241).
3. Hydrolysis: (a) loss of weight after boiling the raw fibre with a I% caustic soda solution for five minutes; (b) loss after boiling for one hour.
4. Determination of cellulose : the white residue after (a) boiling for five minutes with i% caustic soda, (b) exposure to chlorine gas for one hour, (c) boiling with basic sodium sulphite solution.
5. Mercerizing : the loss of weight after digestion with a 20% solution of sodium hydrate for one hour in the cold.
6. Nitration : the weight of the product obtained after diges tion with a mixture of equal volumes of sulphuric and nitric acids for one hour in the cold.
7. Acid purification : treatment of the raw fibre with 20% acetic acid for one minute, the product being washed with water and alcohol, and then dried.
8. Determination of the total carbon by combustion.
For hat and matting manufactures a large range of the fibrous products above described are employed, chiefly in their natural or raw state. (See also ALPACA; COTTON ; FELT ; FLAX ; HEMP ;