Natural cellulosic fibres

Cotton and Other Cellulosic Fibres. The dominant natural cellulosic fibre is cotton, the other natural cellulosic fibres, or bast fibres, include flax, linen, jute and ramie. The so-called regenerated fibres, which include viscose, modal fibres and lyoceU (Tencel), are made by various chemical treatments of cellulosic substrates. The dyeing and printing of cellulosic fibres and materials is carried out using, in decreasing order of scale and importance, reactive, direct and vat dyes. ... 

At the present moment it is difficult to decide which of the two hypotheses concerning the structure of cellulose is correct the idea of an amorpho-crystalline structure, or that postulating solely an amorphous texture. Nikitin assumes that the first hypothesis is the more probable, more especially as it is well in line with the most recent work of Zaydes and Sinitskaya [45] who conclude on the basis of electron diffraction investigations that in the natural cellulose fibre of Chinese nettle, there exist phases having a distinct microcrystalline structure. This suggests that structures shown in Figs. 78, 79 and 80 are the most probable. 

The first high-strength carbon fibres were produced in the 1950s (see Donnet and Bansal, 1984). The early carbonized products were rayon-based, but it was soon found that the mechanical properties and the carbon yield could be improved by the use of polyacrylonitrile (PAN) as the precursor. Also, less expensive fibres of somewhat lower strength and modulus could be made from various other precursors including petroleum pitch and lignin. However, cotton and other forms of natural cellulose fibres possess discontinuous filaments and the resulting mechanical properties were consequently found to be inferior to those of the rayon-based fibres. 

The starting point in the textile supply chain is the raw material preparation. Textile fibres are obtained from two main sources natural (cellulose or animal) fibres or synthetic fibres. Natural cellulosic fibres include conventional and organic cottons, rayon, linen, hemp, jute, ramie and sisal. Cotton is used to produce 40% of world textile products (Saicheua et al., 2012). The major environmental concern in cellulosic fibre production, especially for cotton fibre, is the chemical fertilizers and pesticides used during cultivation. The second concern is the high level of water consumption (Dave and Aspegren, 2010 Muthu, 2014). Cotton is one of the most popular natural fibres used in the world. Three percent of the world s cultivated land is used for cotton production and 16% of the world s insecticides are used on this crop alone (Saicheua et al., 2012 Muthu, 2014). Moreover, the use of chemical fertilizers, pesticides, machinery and electricity causes some human health and environmental problems. Also cotton growing requires 7—29 tonnes of water per kg of raw cotton fibres (KaUiala and Nousiainen, 1999). Other types of cellulosic fibres are hemp and flax, which can be considered to be the most significant sustainable fibres in the non cotton natural fibre sector (Werf, 2004 Muthu, 2014). 

Eucolloidal (pol. degree > 500) Natural rubber, synthetic rubbers (neoprene. Buna, Butyl-rubber, Thiokol) Natural cellulose fibres (wood, cotton, flax, hemp) starch pectin. Keratin CO-haemoglobin Serum albumin Haemocyanin ditto, in the highest polymerisation stage Polymerised shellac, damar and copal. Phenol- or urea-formaldehyde between the B-and C-stages... 

Cotton is a soft, fluffy, staple fibre that grows in a form known as a boll around the seeds of the cotton plant. These curly fibres are typically less than 1/8 inch (3 mm) long. It is a natural cellulosic fibre with good strength properties. 

From ATR-FTIR, solid-state NMR, XRD and SEM, it was concluded that the sugar cane fibre consists of cellulose and non-cellulose (fatty acid, wax and hemicellulose). A schematic of a natural cellulose fibre from a sugar cane leaf is shown in Figure 13.11. 

Fahmy TYA, Mobarak F (2008) Nanocomposites from natural cellulose fibres filled with kaolin in presence of sucrose. Carbohydr Polym 72 751-755... 

Today cellulose and the combination of cellulose and lignin, i.e., wood, are of special importance. Billions of tons of COg fixed by the green plants every year are transformed to these products and whole branches of industry are involved in its processing. Natural cellulose fibres (cotton, flax fibers, jute) or fibers produced from the cellulose of wood play an important role in making thread, cloth etc. Cellulose of fast-growing trees is the raw material of paper, and wood is even today one of the most important materials in constructing houses, furniture, etc. 

Natural cellulose fibres (derived from wood chips processed to remove the hgnins and other soluble impurities such as resins and sugars) offer some advantages for precoat filtration, the properties of which are compared with diatomite and perlite in Table 2.20. The fibre lengths vary from about 20 pm to... 

The proposal that transverse sectioning of natural cellulose fibres can be used to test theories on the structure of microfibrils has been examined theoretically. It was concluded that fibre-sectioning experiments described in the literature do not disprove the folded-chain model, and it was suggested that clearly divided sections exist along the axis of the microfibril at intervals of 200 A. This cannot be explained in terms of a fringed micelle model. However, it is possible that cellulose II has a folded-chain conformation, since a single molecule of cellulose can be folded back and forth in the (101) plane to form a sheet-like structure that fits into the unit cell. A cellulose molecule can achieve a sharp U-tum in the... 

PP/flax or /hemp eomposites were obtained in two steps mixing of both eomponents in a roll mill at high temperature and extrusion. There are some important problems to be solved in this proeedure the higher sensitivity to temperature of the natural cellulosic fibres versus the synthetie polymer, eutting of fibres into suitable pieees and preparation of their surface to make it more eompatible with the aliphatic polymer, ete. 

Chand, N., Tiwary, R.K., Rohatgi, P.K., Bibliography resource structure properties of natural cellulosic fibres - an annotated bibliography. Mater. Sci., 23, 381-387 (1988). 

Espert, A., Vilaplana, F., Karlsson, S., 2004. Comparison of water absorption in natural cellulose fibres from wood and one-year crops in polypropylene composites and its influence on their mechanical properties. Composites Part A, Applied Science and Manufacturing 35, 1267-1276. 

Lednicka D, Mergaert J, Cnockaert MC, Swings J (2000) Isolation and identification of cellulolytic bacteria involved in the degradation of natural cellulosic fibres. Syst Appl Microbiol... 

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