Anna University Preparation of Textiles for Colouration Exam Paper



IV Semester Textile Chemistry

Preparation of Textiles for colouration

Time : Three hours                                                                                                                                                                                           Maximum : 100 marks

Answer ALL questions.

PART A — (10 ´ 2 = 20 marks)

1. State the various defects that are looked into in the inspection of grey goods.

2. Comment on the techno–economics of the following processes.

             (a)     Yarn singeing followed by knitting the fabric.

             (b)     knitting the fabric followed by singeing it.

3. Comment on need and extent of gum removal from silk materials.

4. State the reasons for use of alkali hydroxides rather than alkali carbonates in mercerisation.

5. What are the various degradations than can occur during cotton scouring?

6. State the differences between copper number and fluidity tests used in the efficiency estimation of scouring process.

7. State the reasons for yellowing of bleached fabrics.

8. Give your views on measurement of whiteness index in bleached fabrics containing optical brighteners.

9. Give the action of sodium bromite in desizing.

10. Write a note on cold scouring operation.

PART B — (5 ´ 16 = 80 marks)

11. Make a comparative discussion on mercerisation and liquid ammonia treatment.

12. (a)     (i)      State the importance of shearing and cropping operations.         (6)

                       (ii)    Give the constructional features and working of a shearing machine.                                (10)


             (b)     Compare in detail the construction and working of openwidth and tubular fabric singeing machines.

13. (a)     Give details about the nature of various impurities present in cotton and the effect of scouring process on these impurities.


             (b)     Discuss about the continuous and discontinuous methods of scouring.

14. (a)     (i)      Compare between bleaching of cotton using various agents.      (12)

                       (ii)    Distinguish between action of whitening and blueing agents.     (4)


             (b)     Discuss on continuous scouring and bleaching ranges used for cotton goods in rope and open width form.

15. (a)     Write short notes on the following :

                       (i)      Swelling of cellulosic fibres in alkaline solutions.

                       (ii)    Enzymes and its uses in textile preparatory operations.


             (b)     Write short notes on the following :

                       (i)      Solubility of cotton and regenerated cellulosic fibres in alkaline solutions.

                       (ii)    combined preparatory operations.


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