Natural fibres structure

Industrial Applications of Natural Fibres Structure, Properties and Technical Applications... 

Miissig, ). (2010) Industrial Applications of Natural Fibres Structure, Properties and Technical Appiications, John Wiley Sons, Ltd, Chichester. 

Thomas S, Paul SA, Pothan LA, Deepa B (2011) In Kalia S, Kaith BS, Kaur I (eds) Natural fibres structure, properties and applications in cellulose fibers bio- and nano-polymer composites. Springer, Berlin, pp 3-42... 

The last example of ToF-SIMS analysis of natural fibres is of a structural characterization of wood species for an eventual dendrochronological study [Saito et al. 2008], The aim of this research was to develop a new method to differentiate heartwood and sapwood. In dendrochronology, when bark is not present on the samples, the presence of sapwood is the key to determining felling date. Usually, heartwood and sapwood can easily been differentiated by their colour, with heartwood being much darker. Nevertheless, in the case of... 

It has been recognised for centuries that certain natural dyes, including alizarin, kermes, cochineal and fustic, now known to contain o-dihydroxy phenolic or anthraquinonoid residues in their structures, can be fixed on natural fibres using oxides or salts of transition metals as mordants. Although mordanted wool dyed with alizarin showed excellent fastness, reproducibility of shade was difficult to achieve because of the variable composition of the raw materials available. The famous Turkey red, in which alizarin was applied to aluminium-mordanted wool in the presence of calcium salts, formed a metallised complex the nature of which remains in considerable doubt. 

Metallisation of fibres is not only a physical process determined by absorption capacity of the fibres for the metal and diffusion capacity of the metal in the fibre structure, but also depends on chemical parameters such as chemical structure of the fibres, presence of functional groups, reactivity of the fibre and the metal, oxidation state of the metal and the presence, necessity and reactivity of supporting chemicals (e.g. reducing agent). Therefore, it was necessary first to study metallisation at different types of fibres in order to investigate which structure is most useful for further research. In this respect, viscose, cotton, natural silk and polyacrylonitrile fibres were investigated because of their different structure and properties and their availability in the New Independent States of the former Soviet Union (Uzbekistan, Kazakhstan, Kyrgyzstan). 

Hemicelluloses are constituted of different hexoses and pentoses glucose, mannose, xylose, etc. Since these heteropolysaccharides are often branched polymers, they cannot constitute crystalline structures. However, their function in the constitution of natural fibres is crucial. Together with lignin, they constitute the bonding matrix of the cellulose microfibres. 

The fibrils in man-made fibres assume a somewhat random position in relation to each other with an overall tendency towards longitudinal orientation, but with many aberrations as shown in Fig. 2.9. The natural fibres of plant origin contain a high proportion of fibrillar structure. The... 

The more fundamental aspects of fiber constitution and behavior are dealt with in Astbury s Fundamentals of Fibre Structure 27) and Textile Fibres under the X-Rays 28), Hermans Contributions to the Physics of Cellulose Fibres 39), and Physics and Chemistry of Cellulose Fibres (40 Marsh s Textile Science (40 Preston s Fibre Science 59) and the High Polymers series of monographs, three of which are concerned with natural fibers—Volume IV, Natural and Synthetic High Polymers, by Kurt H. Meyer 53), Volume V, Cellulose and Cellulose Derivatives, edited by Emil Ott 56), and Volume VI, Mechanical Behavior of High Polymers, by Turner Alfrey, Jr. 21 ... 

As with other natural fibres, silk has a hierarchical microstructure - about five anti-parallel (f-sheets, each with around 12 chains, aggregate to form parallel, crystalline microfibrils (approximately 10 nm in diameter), bundles of which make up fibrillar elements (roughly 1 p,m across), which in turn associate to comprise the individual fibroin filaments (7-12 xm) at each level of organisation, the ordered elements are embedded within amorphous matrices derived from the non-crystalline components. Once again, then, the behaviour of the structural composite can be understood in terms of the semi-crystalline array of its component parts. 

As for linen and other natural fibres, silk is sensitive to a variety of environmentally driven degradative processes, though in most cases the actual damage is caused by hydrolysis and/or oxidation. Attack on the polymer chains is generally initiated in the amorphous zones as a consequence of their more open structure and the incidence of reactive amino-acids (specifically histidine, lysine, phenylalanine, proline, threonine, tryptophan, tyrosine and valine). 

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