Flory-Huggins Parameter

• is also called the heat of mixing [Sperling-74]
  
  
• is the Enthalpy of Mixing
  
  
• k is the Boltzmann constant and T is the temperature.
• is a count of the number of polymer molecules in the solution [Sperling-72]
  
  
• is the volume fraction of solvent [Sperling-74]
  
  
• is sometimes called "the lattice constant of entropic origin" [Sperling-75]
  
  
• R is the real gas constant and T is temperature.
  
  
• is the molar volume of the solvent [Sperling-75]
  
  
• and are solubility parameters
  
  
• [Hiementz-523] calls the "Flory-Huggins Interaction Parameter" and states that it is:
  
  
  1. zero for athermal mixtures
  2. positive for endothermic mixing
  3. negative for exothermic mixing
• [Allcock-418] The Flory-Huggins interaction parameter, is treated as if it were a constant by some equations, but it has been shown to change with polymer concentration (usually an increase.)
  
  Sperling (p. 254) mentions that the interaction parameter and the solubility parameters can be used for calculations involving plasticizers and gives the equation below: