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 (Tc = 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 Tc, etc., are factors for the formation of three uniquely different types of spherulite in PLLA. On increasing Tc from 120 to 130 °C, only hexagonal crystals (Type‐1), can be observed. Spherical‐shape lamellar plates at Tc = 120 °C undergo transformation to stretched‐lamellae plates, Tc = 130 °C, due to the increasing growth rate with increasing Tc.