Natural fibres processing

R. Kozlowski (ed.). Handbook of Natural Fibres Processing and Applications, Woodhead Publishing, Cambridge, UK, 2012, vol. 2. 

Kozlowski RM. Handbook of natural fibres processing and applications. Cambridge Elsevier Science 2012. p. 544. 

The purpose of scouring is to reduce to an acceptable level the amounts of fats, waxes, oils and dirt present. Apart from the aesthetic benefits of a clean substrate, the major technical reason for scouring is to improve the extent and uniformity of absorbency for subsequent processes, especially coloration. Usually the objective is the complete removal of all extraneous matter but on occasion only partial removal is the aim, since a certain residue of oils, for example, will aid such processes as spinning, weaving or knitting. Scouring is particularly important with natural fibres, which obviously contain much more extraneous matter than do synthetic fibres. 

As ToF-SIMS is a surface analytical technique, it is well suited to the study of surface interaction between a material and its environment or between a material and products applied to it. The surface modifications can then be studied, making it possible to establish links with degradation processes. Published papers on the study of natural fibres related to cultural heritage typically illustrate this aspect of ToF-SIMS analysis. 

Sulfonated azo dyes (reactive dyes) are widely used in the textile industry. Due to the simultaneous hydrolysis in the dyeing process, 15-60 % of the reactive dyes reach the waste water system. In addition, their use strongly increases with the colouring of natural fibres, and so a total of 60 % of all dyes emitted to the waste water are reactive materials. 

The third main class of separation methods, the use of micro-porous and non-porous membranes as semi-permeable barriers (see Figure 2c) is rapidly gaining popularity in industrial separation processes for application to difficult and highly selective separations. Membranes are usually fabricated from natural fibres, synthetic polymers, ceramics or metals, but they may also consist of liquid films. Solid membranes are fabricated into flat sheets, tubes, hollow fibres or spiral-wound sheets. For the micro-porous membranes, separation is effected by differing rates of diffusion through the pores, while for non-porous membranes, separation occurs because of differences in both the solubility in the membrane and the rate of diffusion through the membrane. Table 2 is a compilation of the more common industrial separation operations based on the use of a barrier. A more comprehensive table is given by Seader and Henley.1... 

Softener and processing aid for synthetic and natural fibres. Used as a spin finish on acrylic fibres and as a softener on both natural and synthetic fibres. It is particularly effective on acrylics but gives a pleasing soft silky handle on nylon. It is recommended as the softener for chlorine/resin finished wool to overcome the harsher handle resulting from such processes, to aid processing and give a lofty hand. 

In recent years starch, the polysaccharide of cereals, legumes and tubers, has acquired relevance as a biodegradable polymer and is becoming increasingly important as an industrial material (Fritz Aichholzer, 1995). Starch is a thermoplastic polymer and it can therefore be extruded or injection moulded (Balta Calleja et al, 1999). It can also be processed by application of pressure and heat. Starch has been used successfully as a matrix in composites of natural fibres (flax, jute, etc.). The use of starch in these composites could be of value in applications such as automobile interiors. An advantage of this biopolymer is that its preparation as well as its destruction do not act negatively upon the environment. A further advantage of starch is its low price as compared with conventional synthetic thermoplastics (PE, PP). 

The action of alkaline scouring agent is to saponify any residual oils, to neutralise carboxylic acids, to solubilise any sizing materials and to cause dispersion of naturally occuring impurities in natural fibres. Table 4.1 summerises the removal process involved during scouring. 

Although jute is a natural fibre like cotton, it differs in chemical composition. Unlike cotton jute contains a high percentage of non-cellulosic matter (about 40%) and the pre-treatment processes of jute are somewhat different from that of cotton. Scouring of jute with caustic soda under pressure cannot be carried out like cotton because of removal of hemi-cellulose which results in high losses of tensile strength (10-15%) and weight (6-8%). 

These oils are used in the fibre and textile industries either to lubricate the textile machinery or as components of process oils used for the working of natural fibres, the production and processing of synthetic fibres or the finishing of intermediate or final products. Textile oils are often made from technical white oils and oxidation inhibitors plus agents ensuring removal of the oils by washing, even after a long... 

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). 

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... 

Handbook of natural fibres. Volnme 2 Processing and applications... 

Natural fibre composites Materials, processes and properties Edited by A. Hodzic and R. Shanks... 

Textiles for apparel are commonly woven or knitted from natural or manufactured hbres. Natural hbres include ceUulosic fibres such as cotton, hnen and hemp, or protein hbres such as silk and wool. Growing of natural fibres frequently involves significant water, land and chemical use. Natural fibres are biodegradable, however, because of the chemicals used in the finishing and dyeing processes, these fibres can still negatively impact soil and groundwater upon disposal. 

This process is used to recycle fabrics made from natural fibres such as cotton and wool as well as synthetic fibres including polyesters, nylons and blended fibres. Hawley (2006) describes the mechanical processing technique used in facilities in Prato, Italy, where acrylic textiles are shredded down to fibre. In hw example, acrylic garments were sorted and cut up, mechanically shredded to fibre, and then re-spun into acrylic yam for weaving into blanketing (Hawley, 2006). 

DoreTex is a yam-spinning company that focuses on high-end yams. While 60% of the company s output is synthetic, the company s core focus is cotton. This is both because the DoreTex production technology is based on the system used for cotton and because the natural fibre, along with linen, hemp, silk, wool and cashmere, is what ensmes the company s privileged relationship with the fashion industry. Consequently, the application of the decision-making process was focussed on the cotton division. 

There are a limited number of studies in the literature that have compared man-made and natural textiles in the same study under similar conditions. Of course, there is a great deal of available information from the Internet and also from several consultancy studies/research papers that provide comparative figures of natural and man-made textiles. This kind of information on the environmental impact of various textile fibres, processes and technologies under natural and man-made categories of textiles have already been thoroughly reviewed and discussed in the author s previous book (Muthu, 2014). Hence, the same information is not repeated in this chapter this chapter is concerned with studies that have directly compared both natural and man-made textiles under similar conditions/system. 

LCA methodology applied in the development of new polymer composites is a relative new field, but it has already been widely used in many industrial sectors as a very useful tool to drive the choice of materials and processes towards a more sustainable production system. Several LCA applications to both traditional composites and new green composites have pointed out that the benefits of using green composites produced with natural fibres and bio-derived matrices, compared to traditional composites, appear superior, and their market opportunities are increasing for many industrial sectors. 

Biagiotti, J., Puglia, D., and Kenny Jose, M. A Review on Natural Fibre-Based composites-Part I Structure, Processing and Properties of vegetable Fibres, J. Nat. Fibers, 1(2), 37-68, 2004 Italicized data from McGovern, J.N. Fibers, vegetable. In Polymers— Fibers and Textiles. A compendium. University of Wisconsin, Madison, WI, 1990. 

Biagiotti, J. Puglia, D. Kenny, Jose M. A review on natural fibre-based composites-Part I structure, processing and properties of vegetable fibres. Journal of Natural Fibers, 2004, Vol. 1 Issue 2, pp. 37-68. 

Torres, F.G., Diaz, R.M. Morphological characterisation of natural fibre reinforced thermoplastics (NFRTP) processed by extmsion, compression and rotational moulding. 

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