The thermally induced phase separation of poly(p-phenylene benzobisthiazole)/ Nylon 66 molecular composites was followed by small-angle light scattering which showed the development of a scattering ring. The intensity increased and the ring moved towards the main beam as a function of time.
The scattering vector qm and intensity maxima Im scaled as qm~t−∝ and Im~tβ with ∝~ 0.33 and β = 0.91-0.95, in close agreement with the cluster dynamics prediction of Binder. However, at longer times, the increase in both qm and Im slowed down dramatically indicating a different mechanism. The structure function S(x) was used to test the validity of universal scaling for a rigid-rod/flexible coil polymer blend. At large x, S(x) scaled to the power of −2.4 in x, which is in between values predicted for systems with one and two-dimensional diffusion.