  In this paper, we report dynamic Monte Carlo simulation results on the
crystallization of crystalline/crystalline (A/B) symmetric binary polymer
blend, wherein the melting temperature of A-polymer is higher than B-polymer.
Crystallization of A-polymer precedes the crystallization of B-polymer upon
cooling from a homogeneous melt. The morphological development is controlled by
the interplay between crystallization and macrophase separation. With
increasing segregation strength, smaller and thinner crystals form with lesser
crystallinity. During the process, A-polymer crystallizes first followed by the
crystallization of B-polymer in the presence of already crystalline domains
A-polymer. Thus, crystallization of B-polymer slows down influencing overall
crystal morphology. With increasing segregation strength between two polymers,
we observe a decreasing trend in mean square radius of gyration, reflecting the
increased repulsive interaction between them. As a consequence, a large number
of smaller size crystals form with lesser crystallinity. Isothermal
crystallization reveals that the transition pathways strongly depend on
segregation strength. We also observe a path-dependent crystallization behavior
in isothermal crystallization: two-step (sequential) isothermal crystallization
yields superior crystalline structure in both A- and B-polymers than one-step
(coincident).
