DYNAMICS OF GLASS-FORMING POLYMERS - HOMOGENEOUS VERSUS HETEROGENEOUSSCENARIO

The question of whether the primary alpha relaxation in glass-forming systems is homogeneous or heterogeneous in nature is investigated by i ncoherent neutron scattering techniques in glass-forming polymers. It is shown that the momentum transfer dependence of the Kohlrausch-Willi ams-Watts relaxation time allows one to discriminate between these two limiting scenarios. From the results obtained we can conclude that th e apparent stretching of the alpha-relaxation function relates dominan tly to sublinear diffusion and is not a result of heterogeneities in t he material.