Cellulose fibre containing

As a result of these investigations it is generally agreed that naturally-occurring cellulosic fibres contain of the order of 60 to 70 per cent of molecules orientated in crystalline structure. The regenerated celluloses contain 30 to 40 per cent, Terylene 50 per cent, and nylon between 50 and 60 per cent. 

Tetrahedron. See silicate structures. Textile Ceramics. The achievement of artistic effects with combinations of textiles and ceramics, in particular by using viscose-silica fibre, a cellulose fibre containing up to 33% silica, used for fire-resistant clothing and upholstery. Bowls, wall hangings and other ornaments of delicate texture can be produced. Texture. (1) The physical property of a ceramic product determined by the shapes and sizes of the pores and the grading of the solid constituents. The texture can to some extent be evaluated in terms of porosity and permeability additional information is provided by pore size measurement and the total... 

Visil. Trade-name. A viscose silica fibre - a cellulose fibre containing up to 33% silica. Kemira Oy, Finland. 

Cellulose fibre is a possible choice as a replacement for glass fibre [1], Cellulose fibre has attractive characteristics of superior mechanical properties, low density, high aspect ratio, and nonabrasiveness. Besides, unlike other natural fillers/fibres, cellulose fibre contains little extractives, which may reduce emission of volatiles during processing and thus be suitable for extrusion or injection foaming process. However, the mechanical properties of cellulose fibre reinforced composites need to be further improved, especially impact strength. 

Essentially nonionic soil-release agents comprise polyesters, polyamides, polyurethanes, polyepoxides and polyacetals. These have been used mainly on polyester and polyester/ cellulosic fabrics, either crosslinked to effect insolubilisation (if necessary) or by surface adsorption at relatively low temperature. Polyester soil-release finishes have been most important, particularly for polyester fibres and their blends with cellulosic fibres. These finishes, however, have much lower relative molecular mass (1000 to 100 000) than polyester fibres and hence contain a greater proportion of hydrophilic hydroxy groups. They have been particularly useful for application in laundering processes. These essentially nonionic polymers may be given anionic character by copolymerising with, for example, the carboxylated polymers mentioned earlier these hybrid types are generally applied with durable press finishes. 

Fixation in 6-12 hours with a mixture of sodium hydroxide and trisodium orthophosphate, a metering device being necessary. This method is recommended for regenerated cellulosic fibres. This formulation contains the same total amount of alkali as method (1) with the same bath stability, but may be preferred where some buffering capacity is required and sodium silicate is undesirable. 

A vat dye is a water-insoluble colorant containing two or more keto groups. It can thus be brought into aqueous solution by a reduction process (vatting), which converts the vat dye into its alkali-soluble enolic (leuco) form. As the soluble sodium enolate the leuco vat dye has substantivity for cellulose. The application of vat dyes to cellulosic fibres (virtually the only fibre type on which their outstanding fastness properties can be exploited) thus proceeds in four stages ... 

These are defined as anionic dyes with substantivity for cellulosic fibres applied from an aqueous dyebath containing an electrolyte. The forces that operate between a direct dye and cellulose include hydrogen bonding, dipolar forces and non-specific hydrophobic interaction, depending on the chemical structure and polarity of the dye. Apparently multiple attachments are important, since linearity and coplanarity of molecular structure seem to be desirable features (section 3.2.1). The sorption process is reversible and numerous attempts have been made to minimise desorption by suitable aftertreatments (section 10.9.5). The two most significant non-textile outlets for direct dyes are the batchwise dyeing of leather and the continuous coloration of paper. 

Although many types of dye contain sulphur other than in sulphonic acid groups, sulphur dyes are usually considered to be those dyes that are best applied from a sodium sulphide dyebath. Like vat dyes, sulphur dyes are water-insoluble before and after application to cellulosic fibres. Disulphide linkages in the dye molecules are readily reduced by sodium... 

The use of xylanases in the preparation of high-purity cellulosic materials requires that the enzyme preparations be free of any cellulase contamination. Treatments of pulps with xylanase preparations containing cellulases have resulted in damage to cellulose fibres as revealed by a drop in pulp viscosities (12,14,17). Similar pulp treatments in which cellulase-free xylanases were used resulted in increases in pulp viscosities (10,18,19). We have shown recently that an apparent increase in the degree of polymerization of cellulose treated with a cellulase-free xylanase is likely due to the selective removal of xylan, leaving an enriched cellulose residue (20). 

It is impossible to obtain nitrocellulose containing a high percentage of nitrogen by nitration with nitric acid alone. This is explicable by the fact that every concentration, even the strongest nitric acid, causes the cellulose fibres to swell, and thus hinders the diffusion of acid into the fibre mass. Attempts to nitrate cellulose by means of a mixture consisting of nitric acid and sulphuric add have demon-... 

Cotton is the richest source of cellulose, since cotton fibres contain as much as 85-97% cellulose. Cotton consists of the nap covering the seeds of the cotton plant (Gossypium) which grows throughout the whole year in a warm, moderately damp climate (Egypt, southern areas and of United States, and U.S.S.R., India, and China Pacific Islands). The length, thickness and colour of the nap depend on the variety of the plant and on the climate in which it is cultivated. 

The most important azo compounds employed in the manufacture of dyes of this type are those containing the < ,o -dihydroxyazo-, the o-hydroxy-o -carboxyazo- and the o-hydroxy-o -amino-diarylazo systems. It is well established3 33-0 that these form four-coordinate copper and nickel complexes (35) in which the coordination sphere of the metal can be completed by a variety of neutral ligands. In both cases the light-fastness of the parent azo compound is improved as a result of complex formation but the nickel complexes are insufficiently stable towards acid to be of commercial interest as dyestuffs. The history of copper complexes has already been discussed (Section 58.1) and will not be considered further here, although it is worthy of mention that currently the most important copper complex dyestuffs are those containing fibre-reactive systems, e.g. (36), for application on cellulosic fibres. 

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