In view of various contradictory theoretical equations relating the interfacial tension a between phase-separated polymer solutions to the Flory-Huggins interaction parameter of the system, the idea that a should depend on the extent of the 'hump' in the concentration dependence of the Gibbs energy of mixing was studied. This investigation is based on 12 series of ~r(T) measurements reported in the literature and on additional experiments for the system cyclohexane/polystyrene. To quantify the extent of the 'hump', a reduced 'hump energy' e. was introduced and its value calculated for different temperatures from the measured critical data of the systems. The analysis of the entire experimental material yields a scaling law of the form a= Er, r where F is close to 0.5 for all systems, in contrast to E which varies within a larger interval. Furthermore, e. is related to ~, the relative distance to the critical temperature, by e= AzB; B is approximately 2.4, again relatively independent of the system, in contrast to A. In case of trustworthy values of the scaling parameters, the above relations offer an interesting possibility to estimate a(T) from the sole knowledge of the critical temperature of the system.
Посилання на статтю:
Interfacial tension and interaction parameters / S. Enders, A. Huber and B. A. Wolf // Polymer. – 1994. – Vol 35. – P. 5743-5747.