Chapter 12: study Guide and Self Assessment
This chapter considers why some things mix and some things don’t. Of course, our principal concern is polymer solutions and mixtures of different polymers, usually referred to as blends, but the principles are quite general. This is obviously important in terms of understanding why a polymer will dissolve in certain solvents or which polymers are most likely to form miscible blends. As in some other sections, you will need to recall some elementary thermodynamics if you are to understand what is going on. If the mention of free energy makes you suddenly weak at the knees, go and review thermodynamics at the start of Chapter 11 before starting this chapter!
Objectives
Upon successfully completing this chapter you should:
- Understand regular solution theory and how to obtain simple expressions for the entropy and enthalpy of mixing.
- Know the Flory-Huggins equation and the relationship between the 𝜒 parameter and solubility parameters.
- Be able to derive an expression for the chemical potential.
- Be able to derive the conditions for obtaining a single-phase system and obtain expressions for the binodal and spinodal from the Flory-Huggins equation.
- Be able to understand the limitations of the Flory-Huggins equation.
- Be able to describe qualitatively the excluded volume effect in dilute solutions.
Self-Assessment Questions