Organic fibres

There are now commercially available a large range of laminated plastics materials. Resins used include the phenolics, the aminoplastics, polyesters, epoxies, silicones and the furane resins, whilst reinforcements may be of paper, cotton fibre, other organic fibres, asbestos, carbon fibre or glass fibre. Of these the phenolics were the first to achieve commercial significance and they are still of considerable importance. 

The production of carbon fibres is based on the pyrolysis of organic fibres or precursors. The main starting materials are polyacrylonitrile (PAN) and pitch (coal tar or petroleum asphalt). They can be classified according to their mechanical performances ... 

According to the data in Table 25.5 and to Eq. (25.6) the compressive strength of filaments of refractory materials such as carbon and silicon carbide have compressive strengths about 10 times as large as those of organic fibres. This would seem to be a serious restriction to the use of organic polymers such as aramids in their application in composites. For most of the applications this restriction is of minor importance, however, since long before ac max is reached, instability in the construction will occur. The resistance of a column or a panel under pressure is proportional to the product of a load coefficient and a material efficiency criterion ... 

There is also recognition of the potential for organic fibre products, with Treliske based at central Otago. This 3000-acre family farm runs Merino, Romney and coloured sheep flocks with Angus and Hereford cattle. Fleeces are then selected by hand and spun into undyed, unbleached quality yarns which are hand and machine knitted and exported mainly to the US and Japan. 

While the global organic fibre market is now worth around US 800 million , conventional cotton farmers across the world continue to use some US 2 billion of chemicals per year, within which at least US 819 million are classified as hazardous , and cause substantial damage to the well-being of developing world communities and their environment. 

Gorbunov VN et al. (1979) Shock-resistant aminoplasts reinforced with organic fibre, (NIITEKHIM), Moscow, 1 33... 

Mineral fibres are of natural and synthetic (man-made mineral fibres) origin. These two classifications, in turn, can be subdivided into inorganic and organic fibres. From the wide range of available fibres, those which are significant from both technological and health aspects are asbestos, mineral wool and ceramic fibres. 

Within the ALABC programme, various new SWP separators have been evaluated with respect to their suitability for VRLA batteries [31,40]. These separators vary in their fibre composition, and some also contain silica powder and microglass fibres. The porosity is in the range of 85-88%, which is somewhat less than that of AGM separators. Due to the hydrophobic nature of the organic fibres, the electrical resistance is about 3-5 times higher than that of conventional AGM separators. On the other hand, the SWP separators exhibit lower compressibility, lower contraction on wetting, and better recovery compared with AGM separators. In a separate ALABC task [27], one of these SWP separators (referenced as SWP-7) was compared with a standard AGM the results are compiled in Table 7.14. 

Polymeric microfibre mat. Until recently, the production of absorptive separators from 100% polymeric fibres was limited by the fact that fibre diameters of less than 1 pm could not be produced at reasonable cost. Further developments in polymers, as well as refinements in fibre production, have resulted in the manufacture of mats with a high percentage of fine fibres with a diameter below 1 pm [41]. As these organic fibres (usually polypropylene) are hydrophobic by nature, wettability has to be imparted by additional treatments such as grafting with hydrophilic agents or by co-extrusion with hydrophilic polymers [1]. 

Tube preparation. Tubes (multi-tube gauntlets) are produced from chemically resistant glass or organic fibres (polyester, polypropylene, acrylonitrile co-polymers, etc.) by weaving, braiding or felting methods. The tubes are fixed into the required shape in an appropriate polymer solution and thermally treated. 

A series of parallel spines (current collectors) are connected at the upper end to a common connector bar (connector bus) which ends with a plate lug. The spines are positioned in the centre of tubes made of either woven, braided or felt acid-resistant glass wool or synthetic organic fibres. Depending on their shape (cross-sectional geometry), tubes may be cylindrical (round), elliptical (oval) or rectangular (square). Cylindrical tubes with the spines (current... 

Pegoretti A, Traina M. Liquid crystalline organic fibres and their mechanical behaviour. In Bunsell AR, editor. Handbook of tensile properties of textile and technical fibres, vol. 12. Cambridge Woodhead 2009. pp. 354—436. 

The new organic fibre industry that is rapidly developing across North America and Europe aims at answering these problems. However, there is still the need to address the steadily increasing demand of fibres by an increasing population (now at 7.94 kg per capita for 6.3 billion inhabitants, 2006 see Chapter 5, Figure 5.2). 

Individual glass fibres are isotropic, but carbon and the organic fibres (aramid and polyethylene) are anisotropic and therefore have different... 

It should be noted that certain organic fibres such as the polyaramids (e.g. Kevlar, Nomex) are affected by UV light. This is of importance on thin (single ply) unpigmented sheeting reinforced with these materials, where properties can deteriorate markedly on exposure [48]. 

A word is necessary here about the units employed in this chapter. The unit g dtex" is one familiar to organic fibre scientists. It incorporates the density of the polymer and is based on the definition that fibre or yarn of one tex weighs 1 g per 1000 m length. Since the densities of many of the new fibres to be described are only approximately known (they lie in the region of 1-3-1-5 g cm" ) while the decitex value of a fibre can be determined by weighing a measured length, we have not attempted the conversion to SI units but offer the conversion equations ... 

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