JNTU Polymeric Materials Exam Paper Apr-May 2008

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

SET-I

1. (a) Differentiate between ionic polymerization and coordination polmerisation.

(b) What are Ziegler-Natta catalysts? Explain the mechanism of coordination polymerization in presence of these catalysts. [8+8]

 

2. (a) What is glass transition temperature? Explain the change of state with temperature in polymeric materials.

(b) Explain the concept of various transitions of states associated with low molecular weight compounds and polymeric materials. [8+8]

 

3. (a) With a neat sketch explain Hand Lay-up technique for producing FRPs.

(b) Explain the principle, advantages and disadvantages of Filament-winding technique. [8+8]

 

4. (a) What are photo degradients? Explain its role in polymers.

(b) Explain about colorants in polymeric technology. [10+6]

 

5. (a) Explain the mechanism of the polymerization of ethylene by ziegler process.

(b) What is the trade name of polytetrafluroethylene? Sketch and explain its mer structures. Explain its physical and chemical properties. Also give its applications. [8+8]

 

6. (a) Why phenol formaldehyde or bakelite resin is soluble in alchohol or caustic

alkali? Explain.

(b) Distinguish between cold setting thermo sets and hot setting thermosets.

(c) Why are the thermosets can’t be reheated, remelted or reused like thermoplastics? Discuss. What are the disadvantages of such a phenomenon? Explain. [4+6+6]

 

7. Describe the preparation, properties and uses of polyesters. [16]

 

8. (a) Write short notes on coagulation of rubber.

(b) You want to extrude a complex component from an elastomer. Should you vulcanize the rubber before or after the extrusion operation? Explain.

(c) Explain the physical properties crude natural rubber. [6+5+5]

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