Temperature dependence of morphology of supermolecular structures growing in the thin layer melt of fractions of poly(ethylene oxide)

Poly(ethylene oxide) fractions with molecular weights in the range from 1.55 × 10³ to 1.5 × 10⁵ were studied. The optical microscopic observations of the morphology of supermolecular structures grown isothermally from the melt were used to determine the dependance of structural-morphological changes on temperature. Two morphological transitions were established: (1) a high temperature transition at 49 Ptilde] 3° C from hedritic structures to positive spherulitoids and (2) a low temperature transition at 38 Ptilde] 2° C from positive spherulitoids to negative spherulites. It is supposed that the transition from hedrites to positive spherulitoids proceeds through a transition from b-axis-oriented lamellae with tilted chains to 401] lamellae with chains perpendicular to the lamellar surface.