Small-angle X-ray scattering studies of semidilute polystyrene-cyclohexane solutions

✍ Scribed by Yonglin Xie; Karl F. Ludwig Jr.; Rama Bansil; Patrick D. Gallagher; Xingxiang Cao; Guarionex Morales

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 677 KB
• Volume: 232
• Category: Article
• ISSN: 0378-4371
• DOI: 10.1016/0378-4371(96)00218-x

✦ Synopsis

Small-angle X-ray scattering was used to study semidilute polystyrene-cyclohexane solutions at temperatures from below the coexistence curve to above the O point. Deviations from O point concentration scaling were observed as the coexistence line was approached. A new scaling form is suggested which combines the concentration scaling near the O point with the temperature scaling near a spinodal; it collapses the experimental data. This approach assumes that the "bare" correlation length 30 scales as c -1. The observed low-angle "excess scattering" is best described by the Debye-Bueche random heterogeneity model, rather than the attractive potential model of Medjahdi and co-workers. The "excess scattering" is virtually independent of temperature, suggesting that the inhomogeneities which cause it are not affected by the approaching phase transformation.