Surface Modification of Cellulose Acetate with Cutinase and ...
Surface Modification of Cellulose Acetate with Cutinase and ...
Surface Modification of Cellulose Acetate with Cutinase and ...
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3.3. Bleaching<br />
Enzymatic <strong>Modification</strong> <strong>of</strong> Wool <strong>Surface</strong> - Introduction<br />
Bleaching is a chemical process employed to destroy the natural creamy colourants in<br />
wool <strong>and</strong> produces a whiter wool. This operation is only performed when wool is<br />
intended to be white dyed or light dyed. Bleaching may take place at the sliver, top,<br />
yarn or fabric stages <strong>of</strong> production. Hydrogen peroxide based bleaching recipes are<br />
commonly employed although these compounds can damage wool fibres, due to<br />
progressive oxidation <strong>of</strong> disulfide bonds ultimately forming cysteic acid (Gacen <strong>and</strong><br />
Cayuela, 2000).<br />
3.4. Dyeing<br />
Dyeing operations are used at various stages <strong>of</strong> production to add colour <strong>and</strong><br />
sophistication to textiles <strong>and</strong> increase product value. Wool textiles are dyed using a<br />
wide range <strong>of</strong> dyestuffs, techniques, <strong>and</strong> equipment. Until fairly recently, most <strong>of</strong> the<br />
dyes used on wool were acid dyes. Nowadays, acid, chrome, metal-complex <strong>and</strong><br />
reactive dyes may all be used for the dyeing <strong>of</strong> wool (Pailthorpe, 1992).<br />
3.5. Antimicrobial Finishing<br />
Natural fibres are more susceptible to microbial attack than synthetic fibres, once they<br />
provide the basic requirements for microbial growth (such as nutrients <strong>and</strong> moisture). In<br />
the carpet industry, the antimicrobial <strong>and</strong>/or mothpro<strong>of</strong>ing <strong>of</strong> wool fabric is an<br />
important finishing step. Various chemicals have been applied to wool to control<br />
microbial <strong>and</strong> larval attack, however, more recently, due to environmental concerns,<br />
restrictions have been placed on the type <strong>of</strong> agent which may be employed (Purwar <strong>and</strong><br />
Joshi, 2004; Han <strong>and</strong> Yang, 2005). Magnesium hydroperoxide <strong>and</strong> related compounds,<br />
<strong>and</strong> chitin <strong>and</strong> chitosan based antimicrobial agents are the new generation <strong>of</strong><br />
environmentally friendly antimicrobial agents (Purwar <strong>and</strong> Joshi, 2004). Non-toxic<br />
natural dyes have also been tested on the antimicrobial activity <strong>of</strong> wool <strong>with</strong> good<br />
results (Han <strong>and</strong> Yang, 2005).<br />
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