Effects of Drying Conditions on Properties of Textile Yarns

Abstract

Yarns made from raw cotton, "purified" cotton, mercerized cotton, clothing wool, carpet wool, viscose rayon, cuprammonium rayon, cellulose acetate, and degummed silk were saturated with water and then exposed for periods of 1/2 to 6 hours in air having temperatures of 221° 257 °, and 302° F. and absolute humidities of approximately 1%, 55%, and 95%. After conditioning the dried yarns for at least 24 hours in air of 65% relative humidity and 70° F., measurements were made of the breaking strengths, elongations at break, and moisture contents of the yarns; the fluid ities of dispersions of the cellulosic fibres in cuprammonium solu tion, of the silk in aqueous zinc chloride, and of the acetate in aqueous acetone; and the relative affinities of the cellulosic fibres for the dye Benzopurpurine 4B and of the wools for acid dyes. Heating for 6 hours at 221° F. and each of the three humidi ties weakened all of the yarns. The breaking strength and elonga tion at break of the viscose, cuprammonium, degummed silk, and cotton yarns decreased still more at higher temperatures. In com parison with heating at 1% absolute humidity, heating at 95% absolute humidity resulted in lower breaking strengths and elonga tions at break for all yarns except the raw cotton, higher fluidities, lower affinity of cellulosic fibres and higher affinity of wool fibres for the dyes. Heating for 1/2 hour at 302° F. had little effect on the prop erties of the yarns except the viscose and cuprammonium rayon which were adversely affected. The damage which occurred at a given temperature and humidity inereased throughout the heating period.