irradiation of dissolving pulp by electron beams - Lenzing

In a wide range of CS2 input (36% to 26%
calculated on a-cellulose) and AR from 0.60
down to 0.47 no significant differente in viscose
quality between the irradiated samples and the
conventionally pre-aged pulp was observed.
Upon increase of the cellulose content up to
115.7% of Standard, no benefit was observed by
using irradiated pulp. Only in case of a drastic
reduct-ion of the input chemicals down to 22%
CS; and AR 0.5 the irradiated pulp gave a better
viscose quality than the reference pulp under the
same conditions (Figures 5 and 6). The same
trials iperformed at the 2kg Pilot plant did not
show any statistical differente between irradiated
and conventionally pre-aged pulp (Table 2).
B~JW&KLS. There seems to be a slight tendency
to lower trithiocarbonate formation in the viscose
made from the irradiated pulp.
Fibre properties. Viscose of reduced CS2 content
showed good spinning properties, the spinning
conditions were not optimized. Tenacity and
elonga.tion were not significantly influenced by
the use of irradiated pulp, the tendency is slightly
better for aged pulp.
Tenacity and elongation were significantly
impaired by the reduction of CS2 Charge using
Standard spinning conditions (Figure 7).
69
Brightness and yellowing of fibres were
nega.tively influenced by both the use of
irrad.iated pulp and the reduction of CS2 Charge
(Figure 8).
Table 2. Results of trials at a Pilot plant [averagehange].
conventional irradiated
CS2 l%l Std. 22 Std. 22
Alkali ratio Std. 0.5 Std. 0.5
unfiltered viscose
Filter value, PVC 452 252 393 1156 335 /IO3
125 1167
Filter value, 77 144 230 117169 123 139
KWP 1230
Total particle 12.4 28.3 18.6/17.1 22.1 /3.2
volume [ppm] 17.8 140.0
Time for 43 78 60 70
filtration, min.
viscose spinning dope
Filter value, PVC 528 233 528 134 439 132
/186 /121
Filter value, 26112 47116 40115 43 145
KWP
Total particle 1.2 2.5 1.4 IO.5 1.3 IO.3
volume [ppm] IO.6 11.8
Ball fall [sec] 49 83 60 93
Ripening ind., “H 14.7 6.5 15.9 7.8
aged Standard irradiated aged 22% CS2; AR irradiated 22%
Standard 0.5 CS2; AR 0.5
Figure 7. Tenacity and elongation of fibers at standarcl spinning conditions (Pilot plant trials).