  Polymer blends offer an exciting material for various potential applications
due to their tunable properties by varying constituting components and their
relative composition. Our simulation results unravel an intrinsic relationship
between the phase behavior and crystallization characteristics with the
relative composition of A- and B-polymer in the system. We report simulation
results for non-isothermal and isothermal crystallization with weak and strong
segregation strength to elucidate the composition dependent crystallization
behavior. With increasing composition of low melting B-polymer, macrophase
separation and crystallization temperature changes non-monotonically, which is
attributed to the change in diffusivity of both the polymers with increasing
composition of B-polymer. In weak segregation strength, however, at high enough
composition of B-polymer, A-polymer yields relatively thicker crystals, which
is attributed to the dilution effect exhibited by B-polymer. When B-polymer
composition is high enough, it acts like a solvent while A-polymer
crystallizes. Under this situation, A-polymer segments become more mobile and
less facile to crystallize. As a result, A-polymer crystallizes at a relative
low temperature with the formation of thicker crystals. At strong segregation
strength, dilution effect is accompanied with the strong A-B repulsive
interaction, which is reflected in non-monotonic trend of mean square radius of
gyration with increasing composition of B-polymer. Isothermal crystallization
reveals a strong relationship between composition and crystallization behavior.
Two-step (viz., sequential crystallization) yields better crystals than
one-step (viz., coincident crystallization) for both the polymers.
