The resiliency and modulus of viscose rayon as a function of swelling and temperature

Abstract

Fiber resiliency and stiffness are very important factors in the crease recovery of fabrics, and the effect of water on these properties influences fabric wash-wear behavior, especially with cellulosic fibers. This paper is concerned with the effect of absorbed water on the mechanical properties of viscose rayon fibers and how this effect may be modified by chemical treatment of the rayon.Earlier studies' have shown that for a number of synthetic textile fibers there is a temperature range wherein the resiliency shows a minimum and the modulus shows a considerable decrease. These changes were believed to arise from a glass-rubber transition in the amorphous portion of the fibers. It has been shown by Bryant and Walter from tensile measurements2 and by others3 that the glass transition temperature of fibers can be lowered by absorption of water. Bryant and Walter examined different textile fibers and found that the change in T, brought about by immersion in water increased with the hydrophilic nature of the fiber. Rayon showed no minimum in resiliency in either the wet or the air-dry state over the temperature range studied. However, the resiliency of wet rayon decreased with decreasing temperature from 30 to OOC., while in the same temperature range the modulus increased. These results were interpreted by Bryant and Walter as indicating a T , of greater than 240OC. (the decomposition temperature) for the dry fiber and of less than OOC. for the wet fiber. A second-order transition has been reported for wet rayon4sS in the region of 45OC. based on force-temperature measurements, but the results are in error due to failure to apply a swelling correction.6 Transitions have also been reported for dry rayon at -2OOC. from dielectric studies' and in the region from -20 to -6OOC. from dynamic mechanical measurements,* but these are * Presented before the Fiber Society in Washington, D. C., October 28, 1960. not considered to be the primary transition. The absorption of a plasticizer by a polymer is known to reduce but a change of more than 240OC. is exceptionally large, and we considered this remarkable effect to warrant further study.It follows from Bryant and Walter's suggestion that at intermediate degrees of water absorption the T , of rayon should fall in the measurable range between 0 and 100OC. We have made resiliency and modulus measurements as a function of both water content and temperature. Control of the water content was achieved by immersing the yarn in acetone-water mixtures, in polymer-water mixtures, and in air of different relative humidities. The effects of "wet"-state and "dry"-state crosslinking of rayon on the above properties have also been determined. EXPERIMENTALAll measuremehts were made in a room maintained at 21°C. on 42-filament, 150-denier viscose yarn having 2.5 tpi of twist. The test samples had a gage length of 3 in. and their ends were glued to tabs of phenolic-impregnated paper with a coldsetting epoxide cement. Diamond-shaped holes were punched in the tabs to accommodate the hooks whic...

The Influence of Moisture Content During Resin-Finishing on the Wrinkle Recovery of Cotton Fabrics at 20°C

“…\\'I< occurs a t some interniediate value of nioisture content, the value of which varies with the finishing treatment. This has also been found by other workers [5,6], and the significant feature is that the creases or wrink!es produced during drying a t or near this particular moisture content tend to persist. Another feature of the results is the change in \VR with variation in moisture content of the fibers, over the entire range of moisture content; the maximum change in \\'I< is found for the untreated sample, whereas all the crosslinked samples show smaller orders of change, sample 3 having the minimum change.…”

The Soft-Confined Method for Creating Molecular Models of Amorphous Polymer Surfaces

“…The T g of cellulose has been difficult to measure experimentally since it is estimated to exist near or above its thermal decomposition temperature. The T g of rayon was measured to be greater than 513 K, and for cellulose, it has been estimated from multiple computational methods to be between 243 and 650 K . Just as mentioned above, the T g for a thin film is expected to be 50–70 degrees lower than in the bulk.…”

“…Our work also has highlighted how the nature of the solid surface impacts surfactant behaviors and assembly. − Because of the recent interest in studying the surface of thin films, there is motivation to build molecular models of amorphous polymeric layers and to investigate the physical properties at the atomic level. A polymer layer in a molecular model is a mimic of a thin film produced by spin-coating, for example, and therefore, compared to existing models used to predict bulk characteristics, it may capture more accurately the structural effects due to the presence of an interface. − …”