Light‐scattering studies of phase‐demixing of polystyrene/poly(o‐chlorostyrene) blends

The phase separation of blends of polystyrene and poly(o‐chlorostyrene) has been studied by observing the changing small‐angle light‐scattering profile with time. As a blend is heated to a temperature at which it undergoes phase separation, a light‐scattering maximum is observed which grows in intensity and moves to smaller angles with time. This maximum is associated with a characteristic spacing which increases at a rate which becomes greater at higher temperature or with lower molecular weight. This spacing varies with a power of time as might be expected for domain growth occurring by a viscous flow mechanism. The integrated scattering intensity (invariant) is found to increase initially with time and then remain constant, as is characteristic of phase separation followed by phase ripening.