LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – CHEMISTRY
FIFTH SEMESTER – APRIL 2012
CH 5402/5400 – POLYMER CHEMISTRY
Date : 27-04-2012 Dept. No. Max. : 100 Marks
Time : 1:00 – 4:00
Part – A (Answer ALL questions) (10 x 2 = 20 Marks)
- Draw the structures of polyisoprene and polystyrene.
- Define: Cohesive energy.
- Mention the uses of polyamide and bakelite.
- What is Zeigler-Natta catalyst? Mention its use.
- Why anionic polymerization is also called living polymerization?
- Mention the significance of CMC.
- How does benzoyl peroxide initiate polymerization?
- Mention the conditions for chain end degradation.
- Account for the thermal stability of Teflon.
- What are plasticizers? Give an example.
Part – B (Answer any EIGHT only) (8 x 5 =40 Marks)
- How is the number average molecular weight of a polymer estimated?
- Distinguish between homopolymers and copolymers with examples.
- Discuss the importance of hydrogen bonding in polymers.
- Explain the mechanism of preparation of PVC by cationic polymerization.
- Write a note on step growth polymerization with an example.
- Explain interfacial polymerization with a suitable example.
- Mention any two uses of PTFE, Buna-N and Polyester.
- What are known as zipping and unzipping in polymers?
- How are (i) Nylon-6,6 and (ii) Neoprene prepared?
- Articles made up of polypropylene can be steam sterilized – explain.
- Explain the role of polymer additives in polymerization process.
- Write a note on injection moulding.
Part – C (Answer any FOUR only) (4 x 10 =40 Marks)
- Explain the following with suitable examples
- a) plastics and elastomers b) natural and synthetic polymers (5+5)
- Discuss the mechanism of the preparation of stereo-regular polypropylene using Ziegler-Natta catalyst.
- a) Discuss the mechanism of a free radical polymerization. (6)
- b) Explain auto acceleration in bulk polymerization. (4)
- Explain the acid and base catalysed mechanism of the formation of phenol-formaldehyde resin.
- Explain the conductivity of polypyrrole, polysulphur nitriles and polyphenylene with the factor influencing their conductivity.
- Write a note on the following processing techniques of polymer
- a) Calendring b) Die casting (5+5)
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