A textile fibre formed from cellulose (a constituent of wood pulp), first produced late in the 19th-c. Improvements in manufacturing methods have made modern rayon fibres important as domestic and industrial materials.
History
Rayon is produced from naturally occurring polymers and therefore it is not a synthetic fiber, but a manufactured regenerated cellulosic fiber. Rayon was only produced as a filament fiber until the 1930s when it was discovered that broken waste rayon could be used in staple fiber. The physical properties of rayon were unchanged until the development of high-tenacity rayon in the 1940s. Further research and development led to the creation of high-wet-modulus rayon (HWM rayon) in the 1950s .
Major fiber properties
Rayon is a very versatile fiber and has the same comfort properties as other natural fibers and can imitate the feel and texture of silk, wool, cotton and linen. Recommended care for regular rayon is dry-cleaning only, HWM Rayon can also be machine washed .
Gallery of textures
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A sample of rayon from a skirt, photographed with a macro lens. |
Physical structure of rayon
Regular rayon has lengthwise lines called striations and its cross-section is an indented circular shape. Rayon fibers are naturally very bright, but the addition of delustering pigments cuts down on this natural brightness .
Production method
Regular rayon (or viscose) is the most widely produced form of rayon. The process is as follows:
CELLULOSE: Production begins with processed cellulose IMMERSION: The cellulose is dissolved in caustic soda PRESSING: The solution is then pressed between rollers to remove excess liquid WHITE CRUMB: The pressed sheets are crumbled or shredded to produce what is known as "white crumb" AGING: The "white crumb" aged through exposure to oxygen XANTHATION: The aged "white crumb" is mixed with carbon disulfide in a process known as Xanthation YELLOW CRUMB: Xanthation changes the chemical makeup of the cellulose mixture and the resulting product is now called "yellow crumb" VISCOSE: The "yellow crumb" is dissolved in a caustic solution to form viscose RIPENING: The viscose is set to stand for a period of time, allowing it to ripen FILTERING: After ripening, the viscose is filtered to remove any undissolved particles DEGASSING: Any bubbles of air are pressed from the viscose in a degassing process EXTRUDING: The viscose solution is extruded through a spinneret, which resembles a shower head with many small holes ACID BATH: As the viscose exits the spinneret, it lands in a bath of sulfuric acid resulting in the formation of rayon filaments DRAWING: The rayon filaments are stretched, known as drawing, to straighten out the fibers WASHING: The fibers are then washed to remove any residual chemicals CUTTING: If filament fibers are desired the process ends here.High Wet Modulus rayon (HWM) is a modified version of viscose that has a greater strength when wet. Due to the environmental effects of this production method, cupramonium rayon is no longer produced in the United States .
Producers
Trade names are used within the rayon industry to determine the type of rayon used.
Bemberg, for example, is a trade name for cupramonium rayon that is only produced in Italy due to EPA regulations in the US .
MODAL is a widely used form of rayon produced by Lenzing Fibers Corp.
Galaxy, Danufil, and Viloft are rayon brands produced by Kelheim Fibres, a German manufacturer.
North American Rayon Corp of Tennessee produced viscose rayon until its closure in the year 2000.
Grasim of India is the largest producer of rayon in the world (claiming 24% market share).
Uses of rayon
Some major rayon fiber uses include apparel (e.g.
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