Correlation of regenerated fibres morphology and surface ... - Lenzing

Lenzinger Berichte, 82 (2003) 83-95
[37] has reported that the extent of crystallites
disorientation in cotton depends on the extent
of swelling and this may also be true for
regenerated cellulose fibres
Figure 5. Randomised scattering curves with amorphous
scattering for untreated, bleached and mercerised viscose
fibres
crystallinity index
0.6
0.4
0.2
0.0
Viscose Modal Lyocell
untreated bleached mercerised
Figure 6. Crystallinity index of untreated and pre-treated
regenerated cellulose fibres
90
ISV
140
120
100
80
60
40
20
0
Viscose Modal Lyocell
untreated bleached slack mercerised
Figure 7. Iodine sorption value of untreated and pretreated
regenerated cellulose fibres
. The results of crystalline orientation for
treated regenerated cellulose fibres are
presented in Figure 8.
Crystalline orientation
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Viscose Modal Lyocell
untreated bleached mercerised
Figure 8. Crystalline orientation of untreated and pretreated
regenerated cellulose fibres
Different degrees of crystallites orientations of
untreated fibres were expected and finally
observed because it is conditioned by the
differences in production processes. The
orientation increases from CV to CLY and
CMD. This does not correlate with earlier
results, where CLY showed the highest degree
of orientation [33], but it correlates well with
the tensile strength reported here and explains
the high tensile strengths of CMD and CLY
fibres (Figure 9). Disorientation due to
molecular relaxation is observed with viscose
and especially modal fibres in the case of the
bleaching process and happens also by the
mercerisation of CMD. The increase of viscose
fibres orientation due to mercerisation may be