**1. Introduction**

Wool consists principally of one member of a group of proteins called keratins; other mem‐ bers of this group include the proteins of hair, feathers, beaks, claws, hooves, horn and even certain types of skin tumour [1]. The main substance of wool is a keratin. Keratin macromo‐ lecules are crosslinked with cystine residues and contain a variety of side chains, some basic and some acidic [2]. Wool fibers consist of cortical cells and cuticular cells, which are located in the outermost part of the fiber surrounding the cortical cells. They consist of endocuticle, A and B exocuticle, and an exterior hydrophobic thin membrane called the epicuticle [3]. Both layers have a tremendous influence on dyeing because of their hydrophobic character‐ istics. The cuticle is separated from the underlying cortex by the intercellular material, which is called the cell membrane complex (CMC) and consists of non-keratinous proteins and lipids [2].

The morphology of the wool fiber surface plays an important role in textile finishing proc‐ esses. The covalently bound fatty acids and the high amount of disulphide bridges make the outer wool surface highly hydrophobic. Especially in the printing and dyeing of wool, the hydrophobic character of the wool surface is disturbing. Diffusion of the hydrophilic dyes at and into the fibers is hindered. For this reason, the hydrophilicity and dyeability properties of the wool fiber should be developed [4]. Wool dyeing is a degradative process involving high temperature for long periods in acidic to neutral pH medium to achieve good penetra‐ tion, optimum fastness, and dye uptake. The results can be harsh handle, discomfort, and a deterioration of properties that impact consumer wear, care, and aesthetic appreciation [5].

Silk fiber is protein fiber that is produced from silk worms [6]. Silk has been called "the queen of fibers", its natural luster, handle and draping properties being superior to those of many other textile fibers [7]. It is composed of different alpha amino acids orienting to form

long chain polymer by condensation and polymerization. Silk fiber consists of 97% protein and the others are wax, carbohydrate, pigments, and inorganic compounds. The proteins in silk fiber are 75% fibroin and 25% sericin by weight, approximately. The sericin makes silk fiber to be strong and lackluster; therefore, it must be degummed before dyeing [6]. Silk fi‐ broin, like wool keratin, is formed by the condensation of α-amino acids into polypeptide chains, but the long-chain molecules of silk fibroin are not linked together by disulfide bridges as they are in wool. Chemical treatments can cause modification of main peptide chains, and side chains of amino acids, which in turn influence the fiber's chemical, physical, and mechanical properties [8]. Silk fiber is easily damaged when dyeing at the boil, so lowtemperature dyeing is usualy preferred [7]. Because the brilliancy of dyed and printed silk fabrics is a decisive factor for evaluating the quality of silk fabrics, dyeability of silk fibers is one of the most attractive topics for applied and basic research [9].

In recent years, many attempts have been made to improve various aspects of dyeing, and new technologies have been, and are being developed to reduce fiber damage, decrease en‐ ergy consumption and increase productivity [10]. In this chapter, new technologies that im‐ prove the dyeability of proteinous fibers such as ultrasound, ultraviolet, ozone, plasma, gamma irradiation, laser, microwave, e-beam irradiation, ion implantation, and supercritical carbondioxide will be overviewed.

**Figure 1.** Classification of sound according to the frequency [14]

**Figure 2.** Formation of a cavitation buble [16]

Power ultrasound can enhance a wide variety of chemical and physical processes, mainly due to the phenomenon known as cavitation in a liquid medium that is the growth and ex‐

The Use of New Technologies in Dyeing of Proteinous Fibers

http://dx.doi.org/10.5772/53912

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