STUDIES ON LOWERING OF THE DEGREE OF SWELLING OF RAYON

Abstract

An apparatus was constructed in order to let rayon tow or sliver pass through high pressure steam and to heat-treat it continuously and the properties of the treated rayon was studied. The treating temperature was 140_??_495°C corresponding to the steam pressure 3_??_14kg/cm2 and the time of treatment was 20-60 seconds.The degree of swelling of a textile rayon dropped by this treatment to 1.60_??_1.53 from 2.06_??_1.97 of the untreated one, and that of the high-tenacity rayon also to 1.6. Such low degree of swelling of textile rayon could be obtained only by this treatment. The depolymerization during the treatment was within 5% and less than that during the high temperature water treatment.The tenacity of the treated yarn increased by 10_??_20%, while the elongation increased in some cases but decreased in the others. The stress-strain test of the treated yarn was carried out in the mediums of various swelling power such as air of 65% RH, water and 0.5_??_1.5 N NaOH aq. solutions. Their S-S curves became steeper toward the stress axis as the treatment became more severe. So a part of the net-structure caused by the treatment likely resists against the swelling in such mediums.The degree of swelling of rayon can be lowered effectively by the steaming, irrespecctive of the yarn form, tow or sliver.