Fractionated crystallization, polymorphic crystalline structure, and spherulite morphology of poly(butylene adipate) in its miscible blend with poly(butylene succinate)

It has been investigated the effects of poly(butylene succinate) (PBS) component on the fractionated crystallization, crystalline structure, and spherulite morphology of polymorphic poly(butylene adipate) (PBA) with melting temperature lower than that of PBS in their miscible binary blends. Fractionated crystallization of the PBA component occurs upon blending with PBS depending on the content and crystallization temperature of the PBS component. It is probably related to the distribution of PBA in the PBS matrix. The PBS component suppresses the crystallization of PBA, due to the physical confinement effect of PBS on the PBA component. PBS is favorable for the formation of the PBA α-crystal in the PBS/PBA blends with C_PBS ≤ 70%, suggesting that the polymorphism of PBA can be regulated by PBS. The morphology observation reveals that the spherulite growth direction of PBA is controlled by that of PBS. Furthermore, the morphology of PBA is also manipulated by that of PBS rather than the crystallization temperature. The possible mechanism of morphology generation of PBA controlled by PBS has been proposed. The PBS/PBA blend system is an ideal system to study not only on the polymorphism regulation but also on morphology control of biodegradable polymorphic material by polymer blending without losing the biodegradability.