Small-angle neutron scattering study of interdiffusion in polymer blends

Earlier investigations on the theory of scattering from diffusing polymer blends are generalized to apply to non-ideal blends which are homogeneous at thermodynamic equilibrium. A significant difference between the procedure used here and that of previous authors is the emphasis on the different time dependence of the intramolecular and intermolecular contributions to the scattering. The generalized results include the original results and the Cook-Binder equation as limiting cases. The importance of the theory is its applicability to extract very small diffusion coefficients of the order of 10;Binary polymer blends prepared in nonequilibrium states were allowed to interdiffuse. The general features of the resulting scattering curves taken at different annealing times followed the predictions from the theory. At low q, the scattering intensity decreases with increasing annealing time while at high q the scattering intensity increases with annealing time. The crossover region was clearly observed.;For blends of polystyrenes with mismatched molecular weights, interdiffusion coefficients of the order of 10;Interdiffusion between polystyrene and poly(xylenyl ether) at temperatures 20...