Factors during Spinning Which Influence the Physical Properties of

INDUSTRIAL A N D ENGINEERING CHEMISTRY

March. 1931

297

Factors during Spinning Which Influence the Physical Properties of Rayon-11' Philip C. Scherer, Jr., and Robert E. Hussey V I R G I N I A POLYTECHNIC INSTITUTE,

I

N A previous article [IND.ENG.CHEM., 22, 594 (1930)]

the authors showed the effect of the time of contact with the acid spin bath upon the physical properties of viscose rayon. It was found that there was an optimum time, for each temperature of the bath, at which the maximum physical properties should be attained. I n the present investigation the effect of changing temperature of the spin bath upon such physical properties has been studied.

BLACKSBURG, VA.

I n Series C the thread was spun through a bath contact of 7 inches (18 cm.), and wound directly upon the spool without pretreatment with alkali. Results

The results are given in Table I and plotted in Curves 1 and 2. Table I

*I contact

S A

EXPERIMENT TEMPERATURE TENSILE STRENGTH ELONGATION, DRY c. Grams per denier % Series A-NHcCI ripeness, 8.4; speed of spin, 8 meters per minute; time of contact, 10 seconds

1 2 3 4 5 6 7

S Series B-NHICI

I v I?. It.

i

Temperature of

Bath

So that the confusing effect of too many variable conditions might be eliminated, all factors affecting spinning were kept constant except temperature. Experimental Procedure All the viscose sirups were prepared from Brown Company "alpha" wood pulp A weight of 610 grams air-dry stock containing 4.7 per cent moisture and 95.3 per cent alphacellulose was dipped in 18 per cent sodium hydroxide a t 20" C. for 1 hour. The soda-cellulose sheets were then removed and pressed to a wet weight 3.33 times that of their alphacellulose content. 'They were then ground in a Werner & Pfleiderer shredder for 2 hours and aged a t 18" C. for 3 days. The crumbs on analysis contained 31.5 per cent stock and 14.0 per cent sodium hydroxide. They were xanthated at 25" C. with 37 per cent carbon disulfide for 11/2 hours and made up into a sirup containing 7.4 per cent cellulose and 5.8 per cent sodium hydroxide. The sirup was filtered and ripened a t 18" C. to an ammonium chloride number of 8.O-9.0. The thread was spun at constant speed, on a 22-hole spinneret geared to 150 denier. A setting bath consisting of 10 per cent sulfuric acid and 28 per cent sodium sulfate was used and the time of contact with the acid bath was definitely fixed by running the filament from the acid bath through an ammoniacal bath before spooling. The acidity of the bath was kept constant by titration. After a thorough washing the threads were dried, twisted, and tested for tensile strength and elongation as usual. 1

Received December 3, 1930.

Series C-NHcC1

1 2 3 4

30 1.52 10.0 35 1.38 10.0 40 0.73 12.7 45 0.07 10.2 50 1.16 15.9 55 1.66 20.0 60 1.24 19.3 70 1.11 11.1 ripeness, 8.6; speed of spin, 8 meters per minute; time of contact, 7 seconds 30 1.77 12.3 40 1.52 17.8 50 1.86 13.9 60 1.04 10.6 70 1.57 10.8 ripeness, 8.3; speed of spin, 54 meters per minute; time of spin, 30 minutes 30 1.57 20.0 40 1.64 22.6 23.2 1.69 50 15.8 1.60 60

I n general, a maximum in the physical properties of rayon occurs at some definite temperature of the spinning bath for each time of contact with that bath. Variation from that optimum temperature causes a decrease in the physical properties. I n the previous article the authors pointed out that such a maximum in the physical properties may possibly indicate a point of complete regeneration.

SericsB- seconds c a n act Series C ormalspin

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