ON SPINODAL DECOMPOSITION OF BINARY POLYMER BLENDS UNDER SHEAR FLOWS

A continuum model describing the spinodal decomposition of polymer ble nds under externally applied shear has been developed. Numerical simul ations were conducted for two-dimensional Couette flow. The morphology of the resulting polymer blend was established by competition between diffusion, forced convection and the internally driven flows which ar ise from concentration gradients. Diffusion and the internal flows ten ded to give compact and particulate morphologies. Externally imposed s hear tended to give elongated structures, but a dynamic equilibrium wa s sometimes established. If flow was stopped, the elongated structures were comparatively stable when subjected only to diffusion (Ostwald r ipening) but were unstable when subjected to the internally driven flo ws. These results represent a first attempt at understanding the struc tures of polymer blends prepared in melt processing equipment. Copyrig ht (C) 1997 Elsevier Science Ltd.