Crystal lamellae of mutually perpendicular orientations by dissecting onto interiors of poly(ethylene adipate) spherulites crystallized in bulk form

Three-dimensional dissecting onto interior lamellar structures of spherulites in poly(ethylene adipate) (PEA) in bulk forms crystallized at 28 ± 3 °C were studied in correlation with thin-film forms. Interior morphology in bulk PEA samples revealed onion-like alternating shells. Interior spherulites clearly exposes that the lamellae within the shell interior are composed of stacked plate lamellae in radial direction while the shell surface region are arranged by tangential lamellae. Shell interior and surface correspond to the valley and ridge of ring-banded on the top surface, respectively. Morphology characterization on fracturing patterns further evidence that the shells could be cleaved apart along the shell surface, indicating weak physical connection between these two perpendicularly oriented shells. Further thermal analysis and X-ray results also supported existence of highly ordered lamellar packing into two mutually perpendicular chain orientations in the 28 °C-crystallized PEA bulks, which differed significantly from the randomly oriented lamellae in either 2 or 33 °C-crystallized PEA bulks.