Crystal Polymorphism and Spherulites in Poly(butylene adipate) Diluted with Strongly Versus Weakly Interacting Amorphous Polymers

Polymorphism and ring‐banded spherulites in poly(butylene adipate) (PBA) diluted with poly(vinyl acetate) (PVAc) or poly(hydroxyether of bisphenol A) (phenoxy) were studied. For neat PBA, polymorphism and ring‐banded spherulites occur at overlapped T_c = 28–31 °C (4 °C range). By comparison, ring bands of crystallized PBA/PVAc blend remain similar to neat PBA; while for PBA/phenoxy blend, ring bands are completely disrupted (revealed by surface AFM phase images), owing to strong interchain interactions between PBA and phenoxy. The results summarily demonstrate that the T_c range for polymorphism becomes much wider (T_c = 19–32 °C) with the addition of the amorphous polymers and reveals the phenomenon of ring bands in PBA is not correlated or attributed to its α+β polymorphism.