31—THE SORPTION OF WATER BY CELLULOSE AND EIGHT OTHER TEXTILE POLYMERS: PART III—THE SORPTION OF WATER VAPOUR BY TEXTILE POLYMERS AT 120°C

Abstract

Data on the absorption of water vapour (0—100% r.h.) at 120°C and 150°C are presented and analysed for cotton, viscose, cellulose triacetate, secondary cellulose acetate, drawn nylon 6.6 yarn and Terylene. The cotton and viscose rayon were severely degraded by the treatments in hot water vapour; the two cellulose acetates were, however, only slightly affected chemically during the time-scale of the measurements. All the samples (with the possible exception of the Terylene) showed an increase in crystaliinity and decrease in sorptivity as a result of the treatments. With the two celluloses and the nylon, the effect of temperature on the sorption was normal (i.e., a decrease in sorption with increase in temperature at all values of r.h.). With the two cellulose acetates, however, the 150°C-isotherm crossed over the 120°C-isotherm at high relative humidities. The sorption of water vapour by Terylene at 120°C and 150°C was slightly higher than at 30°—90°C, in agreement with the trend displayed by these low-temperature results. Desorption measurements on cotton, viscose and secondary cellulose acetate showed that these materials exhibited sorption hysteresis at temperatures as high as 150°C (the other polymers were not studied as regards hysteresis at these high temperatures).