Phase behavior, polymorphism and spherulite morphology in Poly(1,4-butylene adipate) interacting with two structurally similar acrylic polymers

Polymorphism and spherulite morphology of poly(1,4-butylene adipate) (PBA) influenced by two structurally similar acrylic polymers: poly(benzyl methacrylate) (PBzMA) and poly(phenyl methacrylate) (PPhMA) were investigated by differential scanning calorimeter (DSC), polarized optical microscopy (POM), and wide-angle X-ray diffraction (WAXD). Characterization first proves that PBA is similarly miscible with PBzMA and PPhMA, respectively, but effects of these two polymers on polymorphism and spherulite morphology of PBA differ dramatically. The depression of PBA growth rate in blends retards the formation of kinetically stable β-form crystal and favors the formation of α-form crystal of PBA. In PBA/PBzMA blend, the spherulite morphology remains all ringless after addition of PBzMA at any Tc, regardless of polymorphism or not. By contrast, the spherulite morphology in PBA/PPhMA blend can change from ringless, ring-banded, to dendritic with respect to Tc. In general, the formation of ring-banded spherulites in either of blends has no relation with the polymorphic crystal cells. Effects of amorphous PBzMA or PPhMA polymers on the polymorphic and ring-banded patterns on PBA differ and were likely controlled by the interaction strength between the two constituents of the blends.