Mechanisms of Multiple Types of Lamellae and Spherulites in Poly( l ‐lactic acid) Interacting with Poly(4‐vinyl phenol)

Multiple types of crystalline morphology are present in low‐molecular‐weight poly( l ‐lactic acid) (LMw‐PLLA) upon blending with poly(vinyl phenol) (PVPh) with 70/30 composition. In such a mixture, three different types of spherulite co‐exist at the same crystallization temperature ( T c = 120 °C), code‐named as Type‐1, Type‐2, and Type‐3, as distinguished from their shape, birefringence, and optical signs. The PLLA molecular weights, the presence of amorphous PVPh, and T c , etc., are factors for the formation of three uniquely different types of spherulite in PLLA. On increasing T c from 120 to 130 °C, only hexagonal crystals (Type‐1), can be observed. Spherical‐shape lamellar plates at T c = 120 °C undergo transformation to stretched‐lamellae plates, T c = 130 °C, due to the increasing growth rate with increasing T c .