FINITE IMPURITY SIZE EFFECTS ON HETEROGENEOUS NUCLEATION OCCURRING INDIBLOCK COPOLYMERS

The role played by heterogeneous nucleation in phase transformations o ccurring in asymmetric, diblock styrene-butadiene is examined using th e experimental technique of time-resolved small-angle x-ray scattering . Transient nucleation effects are clearly identifiable through compar ison of the early time transformation kinetics seen with samples conta ining varying impurity sizes. These results are interpreted in the con text of a simple model of transient nucleation rate incorporated into classical theories of isothermal transformation kinetics.