Natural fibres waxes

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. 

The GALDI-MS measurements covered a selection of natural ester waxes, both from animal (beeswax, shellac wax, spermaceti) and vegetable sources (candelilla, cane, carnauba, cotton fibre, esparto, ouricouri). Generally, the waxes were readily distinguishable by their characteristic distribution of molecular masses. In some cases, markers could be identified on the basis of literature data. 

Natural fibres contain oils, fats, and waxes, together with other impurities. Garments, fabrics, or yarns may contain oil and adventitious dirt collected during manufacturing. The term scouring applies to the removal of these impurities. 

ATR-FTIR, solid state C-NMR and XRD results showed the composition of the fibre surface and the relationship of its characteristic with thermal resistance. The crystalline content of the natural fibre remarkably increased after chemical treatment, which was confirmed by XRD and solid-state C-NMR. HCIO4 is the most efficient chemical in terms of wax and fatty acid residue removal in our work. Hence, the dynamic mechanical properties of the natural fibre after HCIO4 treatment were improved. It was reported that the acidolysis lignins were isolated from sugar cane bagasse and curaua fibres by adding a mixture of dioxane and 0.1 N aqueous HCl (8.5 1.5, v/v) at 100 °C for 2 h under N2. ATR-FTIR and TGA of the oxidized lignins revealed a decrease in... 

Clariant offers a maleated PP imder the Hostamont name. Around the end of 2003 Clariant also introduced a maleated polypropylene wax called Licomont AR 504 as a coupling agent and compatibihser, also for wood and natural fibre composites. The viscosity was deliberately low to facilitate fibre impregnation. Benefits claimed were improvements in the toughness and elasticity of the products. 

With the exception of cotton, the components of natural fibres are cellulose, hemi-cellulose, lignin, pectin, waxes and water soluble substances, with cellulose, hemi-cellulose and lignin as the basic components with regard to the physical properties of the fibres. The concentration of cellulose achieved is 82.7% in cotton and 64.4% in jute. In contrast hemi-cellulose concentration is 5.7% in cotton and 16.7% in flax. Pectin levels are 5.7% in cotton and 0.2% in jute. In contrast lignin levels are 11.8% in jute and 2.0% in flax and do not exist in cotton. The water content is 10% for cotton, jute, flax and sisal [11]. 

If, for particular reasons, additional treatments are used, particularly aqueous based ones, there can be difficulties in obtaining satisfactory wetting of the fabric, on account of the naturally occurring waxes on the fibres. 

For satisfactory whiteness on wool, it is essential for the fibre to be well scoured and bleached, either oxidatively with hydrogen peroxide or by reduction using stabilised sodium dithionite. Brightener is usually applied together with the dithionite bleach. To achieve the highest possible whiteness, the wool should first be scoured to remove natural waxes and other contaminants, then bleached with peroxide and finally treated with FBA during a second bleach with dithionite. 

Natural oils and waxes are mostly mixtures of fatty alcohols, fatty acids and esters of these carbohydrates [27]. Wax content varies greatly among the different varieties of cotton and also same variety grown in different locations. The wax is located on the outside of the cotton fibre and the quantity increases with surface area of cotton [28]. The composition and removal properties of cotton wax are given in Table 1.7. Cotton wax contain carbon (80.38%), hydrogen (14.51%) and TABLE 1.7... 

The loom state cotton fabric contains about 8-12% natural impurities of total weight of the fibre. These impurities mainly consists of waxes, proteins, pectic substances and mineral matters. In addition to this, the mechanically held impurities called motes are present containing seed-coat fragments, aborted seeds and leaves etc. that clinge to the fibre. Apart from these, the loom-state fabric is also contaminated with adventiteous oils such as machine oils, tars, greases etc. 

Scouring is mainly designed to remove the natural oils and waxes from the cotton portion and the finish oils which manufacturer add to polyester fibres when extruded. Blends of polyester/cotton can be scoured with alkaline scouring agents as per conditions shown in Table 4.16. Trisodium phosphate can also be used as an TABLE 4.16... 

M ht scouring operations in which these surface-active compounds are commonly used varv according to the nature of the fibre and the amount and composition of the impurities to be removed. In the case of cotton the cellulose of w hich it is composed is stable to dilute solutions of alkali at the boil. I he imphrities which must be removed are natural oils and waxes, proteins, pectic substances, natural colouring matter, and adventitious dirt. The basic principle of cotton scouring is to boil the goods for several hours at atmospheric, or under elevated, pressure with a 2 per cent solution of sodium h) droxide. 

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. 

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