This is to certify that  Aakash Narayan,  student of Class XII B, Don Bosco School, Alaknanda has completed the project titled ‘Cuprammonium Rayon Threads from Filter Paper’ during the academic year 2010-2011, towards partial fulfillment of credit for the chemistry practical evaluation of CBSE Board, and submitted a satisfactory report, as compiled in the following pages, under my supervision. This project is absolutely genuine and does not indulge in plagiarism of any kind. The references are taken in making this project have been declared at the end of this report. Ms. Cecilia Manichan Don Bosco School, Alaknanda.“There are times when silence speaks so much more loudly than words of praise to only as good as belittle a person, whose words do not express, but only put a veneer over true feelings, which are of gratitude at this point of time. I would like to express my sincere gratitude to my chemistry teacher  Ms. Cecilia Manichan, for her vital support, guidance and encouragement without which this project would not have come forth.
I would also like to express my gratitude to the staff of the Department of Chemistry at Don Bosco School for their support during the making of this project. I would also like to thank my partner, my friend Gaurab Das Gupta helping me to perform the project. Aakash Narayan XII B, Don Bosco School:

Conical flask (250 ml)
Funnel
Glass rod
Beaker (250 ml)
Water bath
Whatman Filter paper

Rayon is a cellulose-based synthetic fiber . it was originally called ‘artificial silk’ or ‘wood silk’, because, it got Developed in an attempt to chemically produce silk. Rayon is a regenerated fiber. cellulose is converted to a liquid compound and then back to cellulose in the form of fiber. cuprammonium rayon is obtained by dissolving cellulose in an ammoniacal copper sulfate solution. The rayon fibers have special characteristics: They are highly absorbent. Cellulose is nature’s own giant molecule. It is the fibrous material that every plant makes by baking glucose molecules in long chains, from seaweed to the sequoia; the chains are bound together in the fibers that give plants their shape and strength. Wood is the main source of cellulose. it contains 40% to 50% cellulose. the substance must be extracted by ‘pulping’. The logs are flaked, and then simmered in chemicals that dissolve the tarry lignin, resins, and minerals.
The remaining pulp, about 93% cellulose, is dried and rolled into sheets-raw material for paper, rayon, and other products. It can be obtained in two ways:

Viscose Process: Cellulose is soaked in a 30% caustic soda solution for about 3 hrs. The alkali solution is removed and the product is treated with carbon disulfide (CS2). This gives cellulose xanthate, which is dissolved in caustic soda (NaOH) solution to give a viscous solution. This is filtered and forced through a spinneret into a dilute sulphuric acid (H2SO4) solution, both of which harden the gum-like thread into rayon fibers. The process of making viscose was discovered by C. F. Cross and E. J. Bevan in 1891.
Cuprammonium Rayon: Cuprammonium rayon is obtained by dissolving pieces of filter paper in a deep blue solution containing tetra-ammine cupric hydroxide. The latter is obtained from a solution of copper sulfate (CuSO4). To it, ammonia solution (NH4OH) is added to precipitate cupric hydroxide (Cu(OH)2), which is then dissolved in excess of ammonia (NH3. )

Reactions: CuSO4 + 2NH4OH > Cu(OH)2 + (NH4)2SO4 (Pale Blue Precipitate)
Cu(OH) 2 + 4NH4OH > [Cu(NH3) 4](OH) 2 + 4H2O [Cu(NH3) 4](OH) 2 + pieces of filter paper left for 10-15 days give a viscous solution called ‘VISCOSE’.
Preparation of Schweitzer’s Solution:

Weigh 20g of CuSO4. 5H20.
Transfer this to a beaker having 100ml distilled water and add 15ml of dilute H2SO4 to prevent hydrolysis of CuSO4.
Stir it with a glass rod till a clear solution is obtained. Add 11ml of liquor ammonia drop by drop with slow stirring. The precipitate of cupric hydroxide is separated out.
Filter the solution containing cupric hydroxide through a funnel with filter paper.
Wash the precipitate of cupric hydroxide with water until the filtrate fails to give a positive test for sulfate ions with barium chloride solution.
Transfer the precipitate to a beaker that contains 50ml of liquor ammonia or wash it down the funnel. The precipitate when dissolved in liquor ammonia gives a deep blue solution of tetra-ammine cupric hydroxide. This is known as SCHWEITZER’S SOLUTION.

II. Preparation of Cellulose material

After weighing 2g of filter paper divide it into very fine pieces and then transfer these pieces to the tetra-ammine cupric hydroxide solution in the beaker.
Seal the flask and keep for 10 to 15 days, during this period the filter paper is dissolved completely. iii. Formation of Rayon Thread. Take 50ml of distilled water in a glass container. To this add 20ml of conc. Sulphuric acid (H2SO4) drop by drop. Cool the solution under tap water. In a big glass container pour some of the solutions. Fill the syringe with cellulose solution prepared before.
Place the big glass container containing H2SO4 solution produced before in ice (the reaction being spontaneous results in excess release of energy in the form of heat which makes the fibers weak and breaks them).
Immerse the tip of the syringe in the solution and press gently. Notice the fibers getting formed in the acid bath. Continue to move your hand and keep pressing the syringe to extrude more fibers into the bath.
Leave the fibers in the solution until they decolorize and become strong enough.
Filter and wash with distilled water.

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