Entropy Change of Mixing

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Sperling's nomenclature used for this equation
Comparison of Sperlings and Hiementz' nomenclature
Definitions of the variables in the equation

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Here we are using Sperling's solution thermodynamic nomenclature

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Hiementz and Sperling use different notation for solution thermodynamics equations:

1. {Hiementz, ,} corresponds to {Sperling, , }
   
   
2. {Hiementz, , } corresponds to {Sperling, , }
   
   However, they are both consisting in the use of the subscripts, 1=solvent; 2=polymer.
   
   

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Definitions of the variables

• is the change in entropy that occurs from the mixing process
  
  
• k is the Boltzmann constant
  
  
• is the number of solvent molecules
  
  
• is the number of polymer molecules
  
  
• is the volume fraction of solvent: and is the volume fraction of the polymer: (Sperling-74)
  
  
  
  • the variable is used to calculate:
    
    
    1. Enthalpy Change of Mixing
    2. Gibbs Free Energy Change of Mixing
       
       
  • The variable is used in the calculation of the
    
    
    1. Flory-Huggens Parameter
       
    2. Enthalpy Change of Mixing
       
    3. Flory-Rehner Equation
       
• x is the the number of chain segments or "mers" in the polymer molecule. I'm not sure why this wasn't just defined as degree of polymerization.
  
  

if you are dealing with a polymer -polymer "solubility" problem, the formulas are different: see (3.19) and (3.20), [Sperling-74]

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Last Update- September 16, 1995- wld

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