MORPHOLOGY OF POLY(ETHYLENE NAPHTHALENE-2,6-DICARBOXYLATE) - FIRST STAGES OF CRYSTALLIZATION

The morphology of poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) w ith a wide range of crystallinities has been determined by transmissio n electron microscopy (TEM). PEN thin films undergoing cold crystalliz ation during annealing at temperatures above T-g have been investigate d after selective chemical staining and cutting in an ultramicrotome. Crystallization appears in amorphous areas distributed in a noncrystal lizable matrix by formation of lamellae inside these amorphous areas. For low annealing temperatures (T-c similar to 145 degrees C), the eme rging morphology of PEN is seen prior to the occurrence of crystallini ty in the x-ray diffraction patten. With increasing time and temperatu re of crystallization, the number and thickness of lamellae increase, in accordance with increasing crystallinity and crystalline thickness, as determined by x-ray investigations. Dendritic superstructures are also observed with a rough starting internal structure that becomes fi ner with increasing crystallization time.