Chemistry Reference
In-Depth Information
Section 2.6
1. What are the two stages of dissolution when a polymer dissolves in a solvent?
2. What is the heat of mixing of binary systems? Write equation.
3. What is the radius of gyration? Write equation
4. Define unperturbed dimensions and expansion factor
Section 2.6.1
1. What is the change in entropy of mixing, according to the Flory-Huggins theory? Explain and
write the equation.
2. What is the change in the free energy of mixing according to the Flory-Huggings theory? Write
equation.
3. What is the Flory temperature? write equation and explain what happens to a solution of a polymer
below this temperature
Section 2.7
1. Define the degree of polymerization
2. What is the DP of polystyrene with molecular weight of 104,000 and poly(vinyl chloride) with
molecular weight of 63,000?
3. What are the important features of chain-growth and step-growth polymerizations? Can you
explain the difference between the two? Can you suggest an analytical procedure to determine by
what mechanism a particular polymerization reaction takes place?
4. What is the DP of polystyrene with molecular weight of 104,000 and poly(vinyl chloride) with
molecular weight of 630,000?
5. Explain the differences between thermosetting and thermoplastic polymers and define gel point.
6. Give the definitions of oligomer, telomer, and telechelic polymers
7. Why must statistical averages be used to express molecular weights of polymers?
8. What is number average molecular weight? What is the equation for number average molecular
weight?
9. What is a weight average molecular weight? What is the equation for the weight average
molecular weight?
10. In a mixture of two kinds of molecules there are ten of each in kind. The molecular weight of
molecules A is 10,000 and the molecular weight of molecules B is 100,000. What is the number
average molecular weight of the mixture and the weight average molecular weight?
11. What is the viscosity average molecular weight and how does it differ from the weight average
molecular weight?
12. What is a molecular weight distribution? What is a monodisperse polymer and a polydisperse
polymer?
13. What is the Mark-Houwink-Sakurada equation? Can you suggest a way to determine
K
and
a
constants experimentally for a given polymer?
14. Give the definitions and formulas for the relative viscosity, specific viscosity, reduced viscosity,
inherent viscosity, and intrinsic viscosity.
15. Why is it necessary to extrapolate to zero (explain how this is done) in order to obtain intrinsic
viscosity.
16. Discuss the various methods of molecular weight determination explain why a particular method
yields a number of a weight average molecular weight, or, as in case of GPC, both.
