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Hydrolysis of regenerated cellulose fi bres for textiles 319

able surface and protein sorption, the surface reactivity of the swollen cel-
lulose structure also has to be considered. Restructuring of the cellulose

fibre surface will change the reactivity for cellulose hydrolysis with
cellulases.
During textile processing e.g. pretreatment, dyeing and fi nishing, goods
are treated in aqueous solutions of auxiliaries at elevated temperatures.
Many steps involve an intermediate drying of the wet material, which can
be thought of as a steam and dry heat treatment. Even during consumer
use, consecutive wet/dry cycles are applied in from of wear and household

wash cycles, which are known to change fibre sorption properties such as
water retention value, moisture sorption or iodine sorption (Siroka et al.,
2008). As the heterogeneous hydrolysis reaction with cellulases involves the
sorption and binding of the cellulose binding domain, any change of cel-
lulose surface can be expected to modulate the cellulose hydrolysis rate for
a given substrate.

13.5 Restructuring by heat and steam treatment

The influence of fibre morphology and cellulose polymer chain order in the

fibre on the hydrolysis rate of cellulose fibres is shown in Fig. 13.3. In the
experiments shown in Fig. 13.3, the production of reducing sugars as func-
tion of hydrolysis time has been studied for cotton (cellulose I crystal
structure), lyocell (cellulose II structure, NMMO process), viscose (cellu-
lose II structure, xanthogenate process) and modal (cellulose II structure,

modified xanthogenate process).

Reducing sugars, cG (g l –1 ) 20

15

10

0 5
0 2 4 6 8
Time (h)
13.3 Production of reducing sugars as a function of hydrolysis time.
−1
−1
Liquor ratio 1 : 25; 0.96 g l protein (30 ml l of enzyme solution); T =
55 °C; , cotton; , lyocell; , modal; , viscose; cG, concentration of
−1
reducing sugars (glucose) in g l .

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