Interface-induced coarsening process in polymer blends

The coarsening process of the droplets in a two-phase polymer blend (PP/EVAc) was studied under two-dimensional and three-dimensional conditions using a phase contrast microscope and computer image analyzer. The results showed that under three-dimensional conditions the growth of the droplet's radius with time follows r(3) similar to t(1.01), corresponding to the evaporation-condensation theory of Lifshitz-Slyozov, r(3) similar to t, while under two-dimensional conditions the growth law is r(3) similar to t(1.31). The growth rate of the droplets under two-dimensional conditions is faster than that under three-dimensional conditions. This difference is caused by an interfacial interaction (wetting effects) between the substrates and polymer blend. The existence of the interface promoted the coarsening process of the polymer blend under two-dimensional conditions. (C) 2001 Academic Press.