Surface Modification of Cellulose Acetate with Cutinase and ...

Subchapter 3.3
The maximum tensile strength supported by wool yarns was drastically lower for
samples treated with commercial subtilisin. This treatment promoted more than 50% of
reduction in the original tensile strength of yarns, indicating higher fibre degradation as
a consequence of enzyme diffusion. On the other hand wool yarns incubated with
chimeric subtilisin-VPAVG220 retained maximum tensile strength comparable to those
of control samples (without enzyme). It seems that the high molecular weight subtilisin-
VPAVG220 is retained at the surface of wool yarns. Since there is a strong reduction of
diffusion of enzyme inside the wool fibres, only the cuticle is under proteolytic attack
what can explain the higher tensile strength of yarns after enzymatic treatment.
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Maximum Tensile Strength (N)
5,0
4,5
4,0
3,5
3,0
2,5
2,0
1,5
1,0
0,5
0,0
Control Control (S) Control
(S+B)
Esperase
Control
Esperase
(S)
Esperase
(S+B)
Subtilisin-
GAG220
Control
Subtilisin-
GAG220
(S)
Subtilisin-
GAG220
(S+B)
Figure 3. Maximum tensile strength (N) supported by wool yarns subjected to different
pre-treatments without enzyme and yarns treated with the same enzyme units of
commercial and chimeric subtilisin.
3.3.3. On yarns induced damage
To evaluate the damage of enzymatic treatment on wool yarns, samples pre-treated as
previously described and incubated with both enzymes were washed for 3 consecutive
cycles in a rota-wash machine. Felting and pilling were visually evaluated (Figure 4).
Both pre-treatments seem to induce a slight degree of damage (although we found no
differences on yarn´s tensile strength) (Figure 3). This degradation is higher when
commercial Esperase is used. Wool yarns treated with Esperase presented a higher level