Polygonal fibres

An alternative approach to develop mechanical anchoring in a fibre was recently suggested by Naaman [72]. It is based on twisting of polygonal fibres (e.g. triangular, square cross section), which allows ribs to be developed. The greater the... 

The sections (Fig. 73, Plate VI) are isolated or in small, polygonal groups with five or six sides, angles mostly well defined and a central lumen which is small and circular or in the form of a short line. When the whole fibre or its section is treated with iodine and sulphuric add, the cell walls are coloured blue, whilst the lumen is seen to contain a granular protoplasmic substance which is coloured yellow. 

New Zealand Flax. This is obtained especially from the leaves of Phormium tenetx. The fibres are united in bundles—which are readily disaggregated—and are very thin, uniform and smooth, with a peculiar appearance of rigidity the lumen is very distinct and occupies about one-third of the fibre (Fig. 80, Plate VIII). The ends are acute. The cross-sections of unbleached fibres are united in bundles which are polygonal with rounded angles they are only weakly joined and the lumen is rounded and free from contents. By iodine and sulphuric add, the raw fibres are coloured yellow, while bleached fibres assume a greenish or blue colour and then show marked flexibility. 

As used today, the word linen is descriptive of a class of woven textiles used in homes. Linens were manufactured almost exclusively of fibres from the flax plant Linum usitatisimum. Today flax is a prestigious, expensive fibre and only produced in small quantities. Flax fibres can be identified by their typical nodes, which account for the flexibility and texture of the fabric. The cross-section of the fibre is made up of irregular polygonal shapes, which contribute to the coarse texture of the fabric. When adequately prepared, linen has the ability to absorb and lose water rapidly. It can gain up to 20% moisture without feeling damp. 

An important component of cuticle is 18 - methyl - eicosanoic acid [40]. Fatty acid is bound to a protein matrix, forming a layer in the epicuticle [41,42], and this layer is referred to as F - layer [43]. The F - layer can be removed by treatment with alcoholic alkaline chlorine solution in order to enhance wettability. The cuticle and epicuticle control the rate of diffusion of dyes and other molecules onto the fibre [44]. The cortex, however, controls the bulk properties of wool and has a bilateral structure composed of two types of cells referred to as ortho and para [45,46]. The cortical cells of both are enclosed by membranes of at least three distinct layers within which the microfibrils fit. Cells of intermediate appearance and reactivity designated meso - cortical have also been reported [47]. Cortical cells on the ortho side are denti-cuticle and thin, those on the para side are polygonal and thick [47]. Fig. 1-7 illustrates the bilateral structure which is responsible for the crimp of the... 

The individual cells of jute are very short. Table 1.11 compares the dimension of ultimate from several sources. The cross-section of jute fibre is polygonal, usually with five or six sides. It has thick walls and a broad lumen of oval cross-section. By contrast with the regular lumen of flax, that of jute is irregular it becomes narrow in plaees quite suddenly. The lengths of various vegetable fibres varies considerably, whereas the diameter is moderately constant from fibre to fibre. 

Flax is stained blue by zinc chloride-iodine reagent (see Section 8.5.6), as are all other cellulose fibres. In addition the typical V- and X-shaped transverse structures can be seen more clearly. Differentiation from hemp can be made by means of a cross-sectional sample. Flax shows clearly visible irregular polygons with lumen, hemp shows relatively indistinct and often conglomerate structures. 

Steel fibres are produced in a variety of types (cold-drawn wire, cut sheet, melt extracted into shaved cold-drawn wire and milled from blocks) and shapes (straight, shaped, round, oval, polygonal or crescent). 

Purthermore, the presence of some impurities on the surface of the okra fibre can also be seen, and the fibres are cemented in non-cellulosic compounds. In particular, the cross-sectional shape of okra fibre shows a polygonal shape that varies notably from irregular shape to reasonably circular, as depicted in Pig. 1.15. Their diameter considerably vary in the range of about 40-180 pm. Purthermore, each ultimate cell is roughly polygonal in shape, with a central hole, or lumen like other natural plant fibres, as shown in Pig. 1.15. The cell wall thickness and lumen diameter vary typically between 1-10 pm and 0.1-20 pm, respectively. As a consequence of it. 

In a novel study, Zou et al. [49] reported nanoscale structural and mechanical characterization of the cell wall of bamboo fibres. They reported the discovery of cobble-like polygonal cellulose nanograins with a diameter of 21-198 nm in the cell wall of bamboo fibres. These nanograins are basic building blocks that are used to construct individual bamboo fibres. Nanoscale mechanical tests were carried out on individual fibre cell walls by nanoindentation. It was found that the nanograin structured bamboo fibres are not brittle in nature but somewhat ductile. Figure 1.17a... 

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