6533b86ffe1ef96bd12cdb17

RESEARCH PRODUCT

Interfacial tension and interaction parameters

subject

description

In view of various contradictory theoretical equations relating the interfacial tension σ between phase-separated polymer solutions to the Flory-Huggins interaction parameter of the system, the idea that σ 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 σ( 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’ ɛ 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 σ = E ɛ F where F is close to 0.5 for all systems, in contrast to E which varies within a larger interval. Furthermore, ɛ is related to τ, the relative distance to the critical temperature, by ɛ = A τ B ; 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 σ( T ) from the sole knowledge of the critical temperature of the system.