Page 258 - Carrahers_Polymer_Chemistry,_Eighth_Edition

Free Radical Chain Polymerization 221

23. What monomer is used to produce PVA?
24. Name one advantage and one disadvantage for the bulk-batch polymerization of PS.
25. Does k increase or decrease when the average DP for a single growing chain goes from 10
p
4
to 10 ?
26. Why is ethylene more readily polymerized by free radical chain polymerization than
isobutylene?
27. What is the termination mechanism in free radical polymerization is the average DP = ν ?
28. The value of ν increases as the polymerization temperature of a specific monomer is increased.

What does this tell you about the termination process?
29. In general, what is the activation energy of termination?
30. Why would not you recommend the use of poly-α-methylstyrene for the handle of a cooking
utensil?
31. Why is polyfluoroethylene generally known by the public as Tefl on?

32. Which would you expect to have the higher chain-transfer constant: (a) carbon tetrafl uoride or
(b) carbon tetrachloride?
33. While the addition of dodecyl mercaptan to styrene causes a reduction in DP, the rate of polym-
erization is essentially unchanged. Explain.
34. Would it be safe to polymerize styrene by bulk polymerization in a 55-gal drum?
35. How does the kinetics of polymerization differ in the bulk and suspension polymerization
methods?
36. Since the monomers are carcinogenic, should the polymerization of styrene, acrylonitrile, and
vinyl chloride be banned?
37. What are some unusual properties of polyfl uoroethylene?
38. Why does not polymerization take place in the droplets instead of in the micelles in emulsion
polymerization?
39. Why doesn’t initiation occur in the micelles in emulsion polymerization?
40. What would happen if one added a small amount of an inhibitor to styrene before bulk
polymerization?
41. Name several places you might “run across” PS daily.
42. Why is the T of PTFE higher than that of FEP?
g
43. Why does an increase in soap concentration increase the average DP and R in emulsion
p
polymerizations?
44. Which will have the higher specific gravity (density): (a) PVC or (b) PVDC?

45. By bulk, why are vinyl-derived polymers used in greater amounts than synthetic condensation
polymers?
46. How might the kinetics change in an initiator if an E of 30 kJ/mol were employed?
a
47. Why were free radical polymerizations studied so well?

48. What is an engineering plastic and is Teflon an engineering plastic?
49. Describe how a plastisol is made.
50. How is PAN made so it can be colored?
51. Compare the properties of PMMA and glass.
52. Why is there a concern over the use of certain plasticizers?

ADDITIONAL READING

Bamford, C. H., Barb, W. G., Jenkins, A. D., Onyon, P. E. (1958): Kinetics of Vinyl Polymerization by Radical
Mechanism, Butterworths, London.
Bhowmick, A., Stephens, H. (2000): Handbook of Elastomers, Dekker, NY.
Buback, M., van Herk, A. (2007): Radical Polymerization: Kinetics and Mechanism, Wiley, Hoboken, NJ.
Cazacu, M. (2008): Advances in Functional Heterochain Polymers, Nova, Hauppauge, NY.
Chern, C. (2008): Principles and Applications of Emulsion Polymerization, Wiley, Hoboken, NJ.

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