Page 127 - Carrahers_Polymer_Chemistry,_Eighth_Edition

90 Carraher’s Polymer Chemistry

25. Which will yield the higher apparent molecular weight values in the light-scattering method:
(a) a dust-free system or (b) one in which dust particles are present?
26. Does HPLC need to be calibrated before it can give absolute molecular weights?
27. Which of the following does modern LC allow the calculation of (a) weight average molecular
weight, (b) radius of gyration, (c) number-average molecular weight, (d) MWD, or (e) polydis-
persity index?

28. What is the significance of the virial constant B in osmometry and light-scattering equations?
29. According to Hildebrand, what is a regular solvent?
30. Which of the two steps that occur in the solution process, (a) swelling and (b) dispersion of the
polymer particles, can be accelerated by agitation?
31. Defi ne CED.
32. For solution to occur, the change in Gibbs free energy must be: (a) 0, (b) <0, or (c) >0.
33. Will a polymer swollen by a solvent have higher or lower entropy than the solid polymer?

34. Define the change in entropy in the Gibbs free-energy equation.
35. Is a liquid that has a value of 0.3 for its interaction parameter a good or a poor solvent?
36. What is the value of the Gibbs free energy change at the theta temperature?

37. What term is used to describe the temperature at which a polymer of infinite molecular weight
precipitates from a dilute solution?
38. At which temperature will the polymer coil be larger in a poor solvent: (a) at the theta temper-
ature, (b) below the theta temperature, or (c) above the theta temperature?
39. If the solubility parameter for water is 23.4 H, what is the CED for water?
40. What is the heat of mixing of two solvents having identical solubility parameters?
41. If the density of a polymer is 0.85 g/cc and the molar volume is 1,176,470 cc, what is the molec-
ular weight?
42. Name some steps that occur when a polymer is dissolved.
43. Why is it important to determine polymer chain length?
44. Why do δ values decrease as the molecular weight increases in a homologous series of aliphatic
polar solvents?
45. Which would be a better solvent for polystyrene: (a) n-pentane, (b) benzene, or (c) acetonitrile?
46. Which will have the higher or greater slop when its reduced viscosity or viscosity number is
plotted against concentration: a solution of polystyrene (a) in benzene or (b) in noctane?
47. What are general typical values for a in the viscosity relationship to molecular weight?
48. When is the Flory Equation similar to the Mark–Houwink equation?
49. What is the term used for the cube root of the hydrodynamic volume?
50. Explain why the viscosity of a polymer solution decreases as the temperature increases.
51. Is MALDI MS restricted to use for natural polymers such as proteins and nucleic acids?
52. Which of the following would you expect to be most soluble in water—ethanol, hexane, or
benzene? Why?
53. If entropy is the driving force for mixing and solubility why is there such a focus on enthalpy
through the various approaches with solubility parameters and other similar values?
54. If MALDI MS is of such great use to biopolymer chemists why is it not more widely used by
synthetic polymer chemists?

ADDITIONAL READING

Albertsson, A. (2008): Chromatography for Sustainable Polymeric Materials: Renewable, Degradable, and
Recyclable, Springer, NY.
Brown, W. (1996): Light Scattering Principles and Development, Verlag, NY.
Carraher, C., Sabir, T, Carraher, C. L.(2009): Inorganic and Organometallic Macromolecules, Springer, NY.
Chabra, R., Richardson, J: (2008): Non-Newtonian Flow and Applied Rheology: Engineering Applications,
Elsevier, NY.

9/14/2010 3:38:02 PM
K10478.indb 90 9/14/2010 3:38:02 PM
K10478.indb 90