Investigatory Project on Preparation of Rayon Thread from Filter Paper

 

INVESTIGATORY PROJECT ON PREPARATION OF RAYON THREAD FROM FILTER PAPER USING CUPRAMMONIUM PROCESS

 

Rayon is the name given to the synthetic fibre made from cellulose, Rayon is one of the first synthetic fibrous materials, made by man, It is also known as ‘artificial silk’ and is used commercially for the manufacture of fabrics like stockings, blouses etc. Rayon is made from cellulose available as cotton, paper, wood etc. Depending on the method of chemical treatment of cellulose, different forms of rayon are known. The process involves the following two stages.

i. Dissolution of cellulose material into a suitable solvant to get a viscous liquid called 'viscose'.

ii. Conversion into threads.

 

AIM OF THE INVESTIGATORY PROJECT

 

To prepare a sample of cuprammonium rayon thread from the filter paper.

 

APPARATUS

 

Conical flask, glass rod, a pair of scissors, glass bath (wide beaker), syringe etc.

 

CHEMICALS

 

Copper sulphate, aqueous solution of NaOH, liquor ammonia, dilute H₂SO₄ and filter paper.

 

PRINCIPLE

 

Cuprammonium rayon is obtained by dissolving the cellulose material in deep blue solution of cuprammonium hydroxide. Cuprammonium hydroxide is prepared by adding liquor ammonia to a saturated solution of CuSO₄ until precipitates first formed redissolve to form a deep blue solution of cuprammonium hydroxide.

 

CuSO₄ + 2NH₄OH → Cu(OH)₂ + (NH₄)₂SO₄

Cu(OH)₂ + 4NH₄OH → [Cu(NH₃)₄](OH)₂ + 4H₂O

[Cu(NH₃)₄](OH)₂ + filter paper → A viscous solution (viscose)

 

Viscous deep blue solution obtained is forced through fine orifices into a bath containing dil. H₂SO₄ to form threads. The threads thus formed are left in the acid solution for 24 hours or until the fibres have acquired required tensil strength.

 

PROCEDURE

 

About 10g of copper sulphate crystals are dissolved in water in a conical flask. Now add 5 ml of liquor ammonia solution dropwise and with constant stirring till the precipitates of copper hydroxide separate out. The precipitate is collected by filtration. After washing thoroughly with distilled water to make it free from sulphate ions, it is dissolved in the minimum quantity of 1 : 1 ammonia solution. The resulting solution is deep blue in colour.

1g of filter paper is cut into small pieces and add to the solvent prepared as above. After stirring the mixture allow it to stand for 3-4 days until the paper has completely dissolved and a clear viscous solution called viscose is obtained.

 

Take the viscose solution in a syringe and place the nozzle of the syringe in a beaker containing dilute sulphuric acid. Squeeze out the viscose into the acid while rapidly moving the nozzle in the acid. Long filaments of rayon appear, which is kept undisturbed for about 24 hours until the bluish colour of the rayon changes to white. Rayon thread is then carefully removed from the glass bath, washed with water and dried by keeping it over filter paper.

RESULT

 

Weight of the filter paper taken = ______g

Weight of Rayon thread formed = ______g

 

Model Viva Voce Questions and Answers

 

1. What is rayon?

Ans: Rayon is the synthetic fibre made from cellulose. It is regenerated cellulose

 

2. What is Schweitzer's solution?

Ans: A solution of tetraammonium cupric hydroxide is called Schweitzer's solution.

 

3. What is the difference between viscose rayon and cuprammonium rayon?

Ans: Viscose rayon is sodium cellulose xanthate whereas cuprammonium rayon is a complex of cellulose and tetrammine cupric hydroxide.

 

4. What are the main sources of cellulose?

Ans: Cotton, linen, wood.

 

5. What is cellulose made of ?

Ans: Cellulose is a natural polymer made of glucose units.

 

4. What is Schweitzer's reagent ?

Ans: Cuprammonium complex, [Cu(NH₃)₄](OH)₂ is called Schweitzer's reagent

 

5. Which form of cellulose is most suitable for fibre formation ?

Ans: Pure cellulose with 96-98% α-cellulose is best suited for fibre formation.

 

6. How can the presence of α - cellulose be detected ?

Ans: α - cellulose is insoluble in 18% NaOH solution at 25°C.

 

7. What is paper made of?

Ans: Paper is made of cellulose (wood pulp).

 

8. Name a few products of cellulose.

Ans: Rayon, acetate rayon, viscose rayon, cupra silk.

 

9. What is artificial silk or art silk?

Ans: Rayon is called art silk.

 

10. Mention the commercial use of rayon.

Ans: To manufacture fabrics like shirts, stockings, net etc.