Page 332 - Advances in Textile Biotechnology

Hydrolysis of regenerated cellulose fi bres for textiles 313

growth in production of cellulose fibres is expected to occur mainly in

the share of regenerated cellulose fibres. Thus, growing interest is

directed towards modification of regenerated cellulose fibres e.g. by cellu-
lase treatment.
The processing of cellulose fabrics and garments with cellulase enzymes
has allowed a wide range of applications, including novel finishes, soft hand,

fuzz and pilling prevention, increase of smoothness and softness, increase
of lustre and colour brightness, improvement of handle and drape, and
fashionable wash down effects (Andreaus et al., 2000; Cavaco-Paulo, 1998;
Cavaco-Paulo and Gübitz, 2003; Cavaco-Paulo et al., 1997; Kumar et al.,
1995).

Although cellulose fibres such as flax, hemp and cotton have been used

for more than 2000 years, the structure of cellulose fibres has not yet been
described in sufficient detail. Differences in the crystal structure between

native cellulose fibres (cellulose I) and mercerised cotton and regenerated
cellulose fibres (cellulose II) have already been detected, but structural

models describing the behaviour of cellulose fibres in aqueous conditions

still need to be developed. In particular, the differences in fi bre structure
of various native and regenerated cellulose fibres in the swollen state will

influence the effect and intensity of a cellulase treatment. Thus, the fi nal

effect of a certain treatment will be influenced by three groups of factors
(Fig. 13.1):
• type of enzyme and treatment conditions (type of cellulase, temperature,
pH, concentration);

• material structure, including fibre swelling and accessibility (cotton,
viscose, lyocell);

• preceding treatments modifying fibre properties and thus observed

enzyme reactivity (retting of flax, bleaching, mercerisation of cotton,
alkalisation of cellulose fibres, drying steps, dyeing).

Cellulase treatment
(endo-, exo-, total
crude cellulase, pH, T)

Cellulase
reactivity

Material structure Preceding treatments
(surface, accessibility, (retting, bleach,
swelling, porosity) alkalisation, drying)
13.1 Schematic presentation of the main parameters infl uencing the
observed cellulase reactivity.

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