Leather structure

The structure of these products is uncertain and probably depends on pH and concentrations in solution. The hydroxyl or carboxyl or both are bonded to the titanium. It is likely that most, if not all, of these products are oligomeric in nature, containing Ti—O—Ti titanoxane bonds (81). Thek aqueous solutions are stable at acidic or neutral pH. However, at pH ranges above 9.0, the solutions readily hydroly2e to form insoluble hydrated oxides of titanium. The alkaline stabiUty of these complexes can be improved by the addition of a polyol such as glycerol or sorbitol (83). These solutions are useful in the textile, leather (qv), and cosmetics (qv) industries (see Textiles). 

Mackey and Weil also list specific NR-P formulas for adhesives for printed circuits, leather-to-leather, bonding steel plates, and Nomex paper ([210], Tables 8 and 19, p. 219). The formula in Table 10, for a general structural adhesive, is also from Mackey and Weil ([210], Table 22, p. 219). 

Surface evaporation can be a limiting factor in the manufacture of many types of products. In the drying of paper, chrome leather, certain types of synthetic rubbers and similar materials, the sheets possess a finely fibrous structure which distributes the moisture through them by capillary action, thus securing very rapid diffusion of moisture from one point of the sheet to another. This means that it is almost impossible to remove moisture from the surface of the sheet without having it immediately replaced by capillary diffusion from the interior. The drying of sheetlike materials is essentially a process of surface evaporation. Note that with porous materials, evaporation may occur within the solid. In a porous material that is characterized by pores of diverse sizes, the movement of water may be controlled by capillarity, and not by concentration gradients. 

Mizell, n., Mizelle,/. micell(e), micella. Mizellenaufbau, m. micellar structure, mk., abbrev. (mikroskopisch) microscopic(al). Mk., abbrev. (Mark, Marken) mark, marks. M.K., abbrev. (Meterkerze) meter candle, mkr, abbrev. (mikroskopisch) microscopic, Mdbel, 71, piece of furniture, -lack, m. furniture varnish or lacquer, cabinet varnish, -leder, 71. upholstery leather, furniture leather, -po-litur,/. furniture polish, -stoff, m. upholstery fabric,... 

Handbook of industrial materials , 2nd edition, I. Purvis, Elsevier (1992) ISBN 0946395837. A very broad compilation of data for metals, ceramics, polymers, composites, fibers, sandwich structures, and leather. Contents include ... 

The practical route for oxidizing leuco diphenylmethanes 15 demands inital conversion to an imine salt 16. The imine salt is obtained by heating a mixture of diphenylmethane, sulfur, ammonium chloride, and sodium chloride at 175°C in a current of ammonia or by heating a mixture of diphenylmethane, urea, sulfamic acid, sulfur, and ammonia at 175°C (Scheme 3). Dyes 16 can be represented as the quinonoid resonance structure 17. Dyes of this class, known as auramines, are all yellow, with the only commercial representative being auramine O 16a. Due to its poor lightfastness and instability to hot acids and bases, its use has been restricted to dyeing and printing cotton, paper, silk, leather, and jute. 

In Chapters 3-6, the commercially important chemical classes of dyes and pigments are discussed in terms of their essential structural features and the principles of their synthesis. The reader will encounter further examples of these individual chemical classes of colorants throughout Chapters 7 10 which, as a complement to the content of the earlier chapters, deal with the chemistry of their application. Chapters 7, 8 and 10 are concerned essentially with the application of dyes, whereas Chapter 9 is devoted to pigments. The distinction between these two types of colorants has been made previously in Chapter 2. Dyes are used in the coloration of a wide range of substrates, including paper, leather and plastics, but by far their most important outlet is on textiles. Textile materials are used in a wide variety of products, including clothing of all types, curtains, upholstery and carpets. This chapter deals with the chemical principles of the main application classes of dyes that may be applied to textile fibres, except for reactive dyes, which are dealt with exclusively in Chapter 8. 

Leather is the material made from animal skin by the process of tanning, which entails chemically altering the composition of the skin so as to make it durable and resistant to decay. Leather is therefore not a protein but a protein derivative. Although the tanning process alters the composition of skin, leather retains the fibrous structure and utilitarian functionality that make skin suitable for multifarious applications. Shelter, clothing, and decorative objects made from leather are, unlike skin or hide, stable to physical, chemical, and biological decay under dry or wet conditions (O Flaherty et al. 1965 ... 

Have you ever wondered about the content of the small packets of granules included in boxes of new electronic devices, leather products, or medications Or have you simply heeded the warning label to dispose of the sachet immediately The granular desiccants in these packets have particular physical properties that enhance their function as drying agents. A look at the chemical structure or chemical properties of these materials provides a better understanding of their capacity to control moisture. 

Lipases, 3 675-676 10 281-282 cotton modification, 8 30 immobilized, 10 306 in leather processing, 10 306 in personal care products, 10 306 Lipid emulsions, 10 130 Lipidil, molecular formula and structure, 5 14 It... 

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. 

Most organic archaeological residues exist as amorphous biological remains in the archaeological record, but since they lack the macroscopic cellular structure present in seeds, wood, leather, or pollen they cannot be recognized by traditional microscopic techniques. Typical residues include food deposits surviving (either visibly on the surface, or invisibly absorbed... 

In the development of the protein-fatty acid condensates it was possible to combine the renewable resources fatty acids (from vegetable oil) and protein, which can be obtained from both animal waste (leather) as well as from many plants, to construct a surfactant structure with a hydrophobic (fatty acid) and a hydrophilic (protein) part (Fig. 4.12). This was carried out by reacting protein hydrolysate with fatty acid chloride under Schotten-Baumann conditions using water as solvent. Products are obtained that have an excellent skin compatibility and, additionally, a good cleaning effect (particularly on the skin) and, in combination with other surfactants, lead to an increase in performance. For instance, even small additions of the acylated protein hydrolysate improve the skin compatibility. An... 

Another RP-HPLC method was applied for the investigation of the effect of TiOz on the photocatalytic degradation of the leather dye Acid brown 14. The chemical structure of Acid brown 14 is shown in Fig. 3.54. Chromatographic measurements were performed in an ODS column using methanol-water (10 90, v/v) as the mobile phase. The flow rate was 1 ml/min and analytes were detected at 212 nm. The results demonstrated that Acid brown 14 is rapidly decomposed under solar light in the presence of a Ti02 photocatalyst [125],... 

The carcinogenic aromatic amines released from azo dyes in leather were investigated by using microwave-assisted extraction (MAE) or supercritical fluid extraction (SFE) followed by RP-HPLC. The chemical structures of dyes and aromatic amines are listed in Fig. 3.69. The flow schemes for SFE and MAE are shown in Figs 3.70. and 3.71. 

At atmospheric pressure the foam structure depends on the formulation and processing parameters. Foamed sheets and imitation leathers can be manufactured by this process. 

An alternative way of classifying dyestuffs is by their application areas, but as there is large overlap between product structural classes and their uses, it is less satisfactory. However, from a commercial standpoint it is the application method that determines the potential of a dyestuff and the reason for its industrial manufacture and sales. In this section the different application methods will be described mainly in relation to the end use, e.g. the dyeing or printing of cotton and other fibres, the coloration of paper or leather, the use in food and cosmetics etc. 

Definition. Some confusion exists even in the definition of tannin included under this name are many substances of varying structure, but having the common ability to transform fresh hides into rot-proof and barely permeable leather. The phenolic nature of these substances has often caused confusion between tannins and phenolic compounds of plants. 

Proteins crosslinked by formaldehyde are important in photography, the leather industry and in bio-medical sciences. Due to the complex structure of the gelatin molecules (consisting of approximately 20 Afferent kinds of amino acids) and the very low crosslink density, it is not possible to detect crosslink resonances under normal conditions. In order to overcome this problem a 13C enriched formaldehyde is used. By comparison with the chemical shifts of model crosslink compounds it is concluded that the predominant crosslink is formed between the lysine and arginine components in gelatin. A possible mechanism for the reaction between these two amino acid components and the formaldehyde has been proposed 154>. 

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