JNTU B.Tech II Semester Examinations, POLYMERIC MATERIALS, Apr/May 2008
(Metallurgy & Material Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. Write short notes on the following:
(a) Ring-opening polymerization
(b) Step polymerization. [8+8]
2. Critically discuss on the classification of microstructures of the polymers with examples. 
3. (a) How the resin be plasticised in blow molding process? Explain different types of methods.
(b) What part of the calendaring machine actually produces the shape of the finished item in calendaring process? [12+4]
4. (a) What are filler materials? Explain the effect of fillers in polymers.
(b) Why lubricants are added to polymeric materials? [8+8]
5. Discuss the various methods of preparation and properties of polystyrene. Also give the important applications of polysterene. 
6. (a) How much of formaldehyde is required to completely cross link 10 kg of phenol to produce a thermosetting polymer? How much by product is produced?(Assume any required data)
(b) Discuss about carothers equation.
(c) What is the difference between the number average molecular weight and weight average molecular weight? [8+4+4]
7. (a) What are polyesters? Distinguish between unsaturated and saturated polyesters.
(b) What is PETP? How is it manufactured? What are the raw materials used? Give the properties and uses of PETP. [8+8]
8. (a) Mention some of the important synthetic rubbers and give their applications.
(b) Why is sulphur added to the rubber during vulcanization process? Explain.
(c) How can oxygen atoms cross-link the rubber molecules? How can the crosslinking of rubber molecules by oxygen atoms be retarded. [7+4+5]