Surface Modification of Cellulose Acetate with Cutinase and ...

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