Natural protein fibres

In addition to the natural protein fibres wool and silk, fibres have been produced commercially from other proteins. These materials were introduced as wool substitutes but today have little or no significance. Mention may, however, be made of ArdiP products from the groundnut protein and marketed for some years after World War II by ICI. Compared with wool it had inferior wet and dry strength and abrasion resistance. The inclusion of up to 20% ArdiP into wool, however, yielded a product with negligible loss in wearing properties. 

The two most important polyamide fibres are nylon 6.6 (171) and nylon 6 (172) whose structures are illustrated in Figure 7.10. A comparison with Figure 7.1 reveals the structural analogy between natural protein fibres such as wool and polyamide fibres. Polyamides may be dyed using acid... 

R.S. Asquith, Chemistry of Natural Protein Fibres, Plenum Press, New York, 1977. 

For centuries silk is a synonym for luxury garment. It describes a woven textile made of natural protein fibres sptm by the larvae or caterpillars of the domesticated silk moth, Bombyx mori. In this context, spinning does not refer to the textile process of fabricating a yam from a bulk of single fibres by warping and but rather describes the process of transforming an aqueous protein solution into an insoluble protein filament (Kerkam et al., 1991). Thus, silk fibres ate filaments that are spun at the point-of-delivery from feedstock, which can differ widely in detail but are protein based (Vollrath and Porter, 2009). 

The natural protein fibres, such as sheep s wool and dlk, contrast with the fibres prepared firom animal or plant proteins. Exploratory tests have shown that the thermolysis of these natural fibres begins at about 250° and continues almost to 400 °C. 

Ryadnov, M. G., and Woolfson, D. N. (2003a). Engineering the morphology of a selfassembling protein fibre. Nature Mat. 2, 329-332. 

The chemical bonds are found in the naturally-occurring protein fibres. Salt linkages between adjacent amino and carboxyl groups probably exist in wool,... 

Polyamides can, as a rule, be brightened with those products suitable fi protein fibres. They have, however, an affinity for insoluble dispersions ( organic compounds and, because of their hydrophobic nature, it is on derivatives of this type that can be applied to polyesters. Water-insolub fluorescent brightening agents, in the form of dispersions, are based, one example, on compounds derived from (12) which are favoured becau of their comparatively good light-fastness ... 

The group includes many natural and synthetic dyes, the latter usually being obtained from anthracene. They have no natural affinity for textiles but are applied to cellulosic or protein fibres which have been mordanted previously with a metallic oxide. The acid mordant dyes are a special class of dyes applied to wool or polyamide fibres as if the were acid dyes, and then given very high wet-fastness by subsequent mordanting. 

Cellulosic fibres have, for all practical purposes, no affinity for basic dyes. A few such as Auramine (C.I. basic yellow 2), Magenta (C.I. basic VIOLET 14), and Methyl Violet (C.I. basic violet 1) have some affinity for cotton, but the wet-fastness leaves very much to be desired. In the case of the protein fibre there is substantial evidence that the affinity is of a chemical nature. The reaction is essentially one of salt formation as shown ... 

Sulphur dyes cannot be applied to protein fibres by normal methods on account of the strongly alkaline nature of the dye liquors. Wool is never dyed with these dyestuffs, but a reasonably fast black was obtained on wool and cotton unions by adding 5 per cent on the weight of the goods of a protective colloid such as glue or boiled starch. 

Wools and other similar mammalian hairs are largely composed of keratin proteins. However, unlike the other natural proteinaceous fibre, silk, wool is cellular in nature the fibres consist of relatively hard, flattened, overlapping cuticle cells, which surround the central cortical cells in some fibres, these may in turn surround a hollow medulla (Figure 23). 

Synthetic fibres, manufactured fibres can be divided into those derived from natural polymers (such as regenerated protein fibres rayon, cellulose acetates, or alginates) and those derived from synthetic polymers including nylons, polyesters, acrylics, and polyolefins. 

Nanofibres can be produced by a number of methods. They can be extracted from natural materials (e.g., cellulose or protein fibres) via physical separation and/or chemical extraction. They can also be produced by means of drawing, template synthesis, phase separation, self-assembly and electrospinning. The details are briefly described below. 

Nanofibrils can be extracted from natural resources, since many cellulosic fibres (such as cotton, hemp, flax) or protein fibres (such as wool, silk from silkworm or spider) have hierarchical structures composed of fibrils in nanoscale sizes. 

Mechanical separation of cellulose fibrils from natural fibre resources may involve the process of grinding to apply shear stress to the longitudinal axis of the fibres, so that the fibrillated fibres will have diameters ranging 20—90 nm (Taniguchi and Okamura, 1998). Ultrasonic extraction is another approach to disrupt the adhesion among the fibrils so as to extract nanofibrils from both cellulosic and protein fibre sources... 

The designers during the early nineteenth century were limited to the fibres, yams and fabrics of that period. These were all natural fibres, which included cotton, flax and protein fibres such as wool and silk. By the middle of the century, other fibres were making their mark on the scene—synthetic fibres were created, such as polyamide, known by its commercial name of nylon. This was followed by polyester and many other synthetic materials, including acetates and spandex fibres, which we know today as Lycra (Figure 6.1). 

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