Answer Happy

Below is shown a figure with the plot of the dominant wavelength of polymer blends that have been experimentally observed undergoing spinodal decomposition. Poly- mer blends have been shown to obey Cahn-Hilliard kinetics. Please explain why the initial wavelengths are observed to be different at the different quench depths. You can base your explanation on the Cahn Hilliard results and on the thermodynamics using a regular solution or Flory-Higgins model for the blend mixture.
140 TUT PMMAD/SCPE55% 120 150°C 100 80 8 8 131°C (wu) V < 60 — 40 20 113°C 0 10 டடா 2 4 6 8 100 2 4 6 8 1000 t(s) Fig. 11. Evolution of the dominant length scale with time for a PMMAD/SCPE blend with 55% SCPE content, and 67.5 w/w% chlorination, for three quench depths at the temperatures indicated. From Flory-Fox, a Tg111°C is estimated for this blend composition, virtually identical to Ts within experimental error. Note how the deeper quenches cross the shallower quench at later times as ripening occurs, as shown in the illustrative calculations of Fig. 5c. Adapted from [73], Copyright 1985.