Brown cupra (also known as cupro or Bemberg) fabric made of rayonLab demonstration of the process. When a solution of cellulose in cuprammonium hydroxide comes into contact with sulfuric acid, the cellulose begins to precipitate from the solution. The sulfuric acid reacts with a complex compound of copper and dissolves it. Thin blue fibers of rayon are formed. After some time, sulfuric acid reacts with the complex compound and washes out the copper salts from the fibers. The fibers become colorless
It is produced by making cellulose a soluble compound by combining it with copper and ammonia with caustic soda. The solution is passed through a spinneret and the cellulose is regenerated in hardening baths that remove the copper and ammonia and neutralize the caustic soda. Cuprammonium rayon is usually made in fine filaments that are used in lightweight summer dresses and blouses, sometimes in combination with cotton to make textured fabrics with slubbed, uneven surfaces.[3]
The fabric is commonly known by the trade name "Bemberg", owned by the J.P. Bemberg company. The fabric may also be known as "cupro" or "cupra". It is also known as "ammonia silk" on Chinese fashion retail websites.
It has a soft, silk-like handle (i.e., tactile feel)[9]
It has similar properties to cotton. It is different in that the average degree of polymerization is lower and a larger part of this fiber is occupied by amorphous regions, causing cuprammonium rayon to swell[9]
It burns rapidly and chars at 180°C[9]
On ignition, it leaves behind ash containing copper[9]
It can be used to create fabric that is sheer and lightweight and has desirable draping properties[4]
Production
Cellulose is dissolved in a [Cu(NH3)4](OH)2 solution and then regenerates as rayon when extruded into sulfuric acid.
References
^"cuprammonium rayon". Retrieved December 1, 2011.
^Burchard, Walther; Habermann, Norbert; Klüfers, Peter; Seger, Bernd; Wilhelm, Ulf (1994). "Cellulose in Schweizer's Reagent: A Stable, Polymeric Metal Complex with High Chain Stiffness". Angewandte Chemie International Edition in English. 33 (8): 884–887. doi:10.1002/anie.199408841.
^"Rayon Fiber". Archived from the original on April 6, 2008. Retrieved December 1, 2011.
^ a bDavidson, Michael W. "Cuprammonium Rayon Fibers". Polarized Light Microscopy Digital Image Gallery. The Florida State University. Retrieved 2 July 2020.
^Over 100 years old and still going strong From Glanzstoff (artificial silk) factory to industry park. industriepark-oberbruch.de
^Verinigte Glanstoff Fabriken merged with the Nederlandse Kunstzijdefabrieken in 1929 to form the Algemene Kunstzijde Unie, AkzoNobel's predecessor.[citation needed]
^Krässig, Hans; Schurz, Josef; Steadman, Robert G.; Schliefer, Karl; Albrecht, Wilhelm; Mohring, Marc; Schlosser, Harald (2002). "Cellulose". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_375.pub2. ISBN 978-3527306732.