Short Wave Length Fluctuations in Phase Separation Process of Polystyrene/Poly(2-chlorostyrene) Blends.

Abstract

Phase separation process of polystyrene (PS)/poly (2-chlorostyrene) (P2-ClS) blends was investigated by time resolved small angle X-ray scattering measurements utilizing synchrotron radiation. Scattered intensity increased initially, and then decreased with the progression of phase separation. The time period in which the scattered intensity increased depended on the wave number and temperature, and became long with the wave number decreased. Because of the wave number dependence of the time period, some wave number region where the intensity decreased from the biggining of phase separation existed in higher wave number region. In the time period in which the intensity increased, the time evolutions of the scattered intensity could be successfully described by the linearized theory of Cahn-Hilliard-Cook except the later time region, indicating that the bigining of phase separation corresponded to the early stage of phase separation. Wave number dependence of the time period in which the scattered intensity increased showed that the time period of the early stage of phase separation became short, and the contribution of the non-linear term in the diffusion equation, which described the time evolution of phase separation, became important with increasing wave number.