Cuprammonium rayon

Merrium-Webster defines Cuprammonium rayon as "a rayon made from cellulose dissolved in cuprammonium solution"^[1]

It is produced by making cellulose a soluble compound by combining it with copper and ammonia. The solution of this material in caustic soda is passed through the spinneret and the cellulose is regenerated in the 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 clubbed, uneven surfaces.^[2]

Properties

There are many properties of cuprammonium rayon ^[3]

Very fine
Produce a soft silk like handle
Has same porperties as cotton except the average DP is lower, and a larger part of this fibre is occupied by amorphous region.
It burns rapidly and chars at 180 deg C.
On ignition, it leaves behind ash containing copper.

Production

The famous polymer cuprammonium rayon is produced using sodium hydroxide, ammonium hydroxide, copper sulfate, and paper. ^[4]

The reaction which are involved are as followed:

NaOH(aq) + CuSO4(aq) ---> Cu(OH)2(s) + Na2SO4(aq)
Cu(OH)2(aq) ---> Cu2+(aq) + 2 OH-(aq)
n Cu2+(aq) + (cellulose)n + 2n OH- ---> (CuC6H8O5)n + 2n H2O

Note: Cellulose is actually dissolved in [Cu(NH3)4](OH)2 solution and then regenerated as rayon when extruded into sulfuric acid.

References

^ "cuprammonium rayon". http://www.merriam-webster.com/dictionary/cuprammonium%20rayon. Retrieved December 01, 2011.
^ "Rayon Fiber". http://www.afma.org/f-tutor/rayon.htm. Retrieved December 01, 2011.
^ "Properties of Cuprammonium Rayon". http://mytextilenotes.blogspot.com/2009/05/properties-of-cuprammonium-rayon.html. Retrieved December 01, 2011.
^ "PRODUCTION OF CUPRAMMONIUM RAYON". http://www.woodrow.org/teachers/ci/1986/exp31.html. Retrieved December 01, 2011.