  The miscibility in several polymer blend mixtures
(polymethylmethacrylate/polystyrene, (1,4-cis) polyisoprene/polystyrene, and
polymethylmethacrylate/polyoxyethylene) has been investigated using Molecular
Dynamics simulations for atomistic representations of the polymer chains. The
trajectories obtained from simulation boxes representing the mixtures have been
analyzed in terms of the collective scattering structure function. The
Flory-Huggins parameter is determined from fits of the simulation results for
this function to the random phase approximation expression. The numerical
values of this parameter and its variation with temperature obtained with this
procedure show a general qualitative and quantitative agreement with existing
experimental data for the different systems. These results together with those
previously obtained for the polyvylmethylether/polystyrene blends with the same
method are compared with data yielded by other computational simpler
approaches.
