Homework answers / question archive / onsider the phase separation of two molecular liquids A and B that are known to follow reasonably well the Flory-Huggins theory of mixing, as discussed in class and in the textbook

onsider the phase separation of two molecular liquids A and B that are known to follow reasonably well the Flory-Huggins theory of mixing, as discussed in class and in the textbook

Unrecognized

Share With

onsider the phase separation of two molecular liquids A and B that are known to follow reasonably well the Flory-Huggins theory of mixing, as discussed in class and in the textbook. The molecular weights and densities of A and B are such that NA= 5, and NB = 1. The temperature dependent value of ? has been estimated as ? = 195/T – 0.45, where T is the absolute temperature (in Kelvin). Experiments have also shown that for this blend ? is not a strong function of either composition or pressure. 1. What is the critical value of the volume fraction of component A ??A,c)? 2. What is the critical value of ? (?c)? 3. What is the critical value of T (Tc)? 4. Calculate and plot the values of the expected order parameter S = (?A’-?A’’) as a function of T near the critical temperature Tc for a blend with critical volume fraction ?A,c. 5. Consider an off-critical blend with ?A= 0.8. At what temperature To is phase separation expected for this blend? 6. Calculate and plot the values of the expected order parameter S as a function of T near To for an off-critical blend with ?A= 0.8. 7. Estimate the parameters a, w, and u for the critical blend using Landau theory: f = ½ a (T-Tc) S2 – w S3 + u S4 8. Estimate the parameters a, w, u, and Tc for the off-critical blend with ?A= 0.8 using Landau theory.