SCATTERING STUDIES OF SELF-ASSEMBLING PROCESSES OF POLYMER BLENDS IN SPINODAL DECOMPOSITION .2. TEMPERATURE-DEPENDENCE

Our previous work on time evolution of the interfacial structure for a near critical mixture of polybutadiene and polyisoprene undergoing the spinodal decomposition (SD) [T. Hashimoto, M. Takenaka, and H. Jinnai, J. Appl. Crystallogr. 24, 457 (1991)] was extended to explore the behavior as a function of temperature T, again using the time-resolved light scattering method. The study involved the investigation of the time evolutions of various characteristic parameters such as the wave number q(m) (t;T) of the dominant mode of the concentration fluctuations, the maximum scattered intensity I(m) (t;T), the scaled structure factor F(x;T), the interfacial area density SIGMA(t;T), and the characteristic interfacial thickness t(I)(t;T) from the early-to-late stage SD, where t refers to time after the onset of SD and x refers to the reduced scattering vector defined by x = q/q(m)(t;T); q is the magnitude of the scattering vector. The results confirm the model previously proposed at a given T over a wider temperature range corresponding to the quench depth DELTA-T = T - T(s) = 5.5-34.5 K, or epsilon(T) = (chi - chi(s))/chi(s) = 4.50 x 10(-2) to 2.79 x 10(-1), where T(s) is the spinodal temperature, and chi and chi(s) are the Flory interaction parameters at T and T(s), respectively. This blend is noted to have a phase diagram of the lower critical solution temperature type.