Effect Of Hydrogen Bonding Strength On The Morphology And Polymorphism Of Poly( Butylene Adipate)

The morphology and polymorphism of poly(butylene adipate) (PBA) and its blend with poly(vinyl phenol) (PVPh) or phenoxy are studied. It is identified that the hydrogen bond strength of PBA/PVPh is higher than that of PBA/phenoxy. The ring-banded structure disappears for PBA/phenoxy, which shows that the formation of a ring-banded structure cannot directly correlate to the hydrogen bond strength. For the polymorphism of PBA, phenoxy does not influence of the polymorph selection compared to the neat PBA. The crystallization temperature range for the coexistence of alpha and beta crystals of PBA/PVPh is slightly narrowed. The crystallization temperature range for the polymorphism is not consistent with the formation of the ring-banded structure. Consequently, the ring-banded spherulites of PBA cannot be correlated to the coexistence of alpha and beta crystals. By contrast, the beta-to-alpha transition temperature is affected by the incorporation of phenoxy and PVPh. The beta-to-alpha transition temperature increases slightly as blending with phenoxy but significantly as blending with PVPh. This is attributed to the enhanced melting point of beta-PBA due to the formation of thicker lamellae when blending with the amorphous polymer. Thus, the melting of the original beta-PBA and accompanied recrystallization alpha-PBA take place at a higher temperature in the blends than that in neat PBA.