Jun Xu - Stabilization of nuclei of lamellar polymer crystals: Insights from a comparison of the Hoffman−Weeks line with the crystallization line.

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      Publication Details (including relevant citation   information):

      Macromolecules, 2016, 49 (6), pp 2206–2215
      DOI: 10.1021/acs.macromol.5b02123
      Publication Date (Web): March 10, 2016

      Abstract:

      We have studied melting of poly(butylene succinate), isothermally   crystallized over a wide temperature range, employing a   combination of the Hoffman–Weeks plot and the Gibbs–Thomson   crystallization line, determined by small-angle X-ray scattering   measurements. A change in the slope α  of the Hoffman–Weeks (H–W) line, accompanied by a change of the   slope of the crystallization line, was observed for   crystallization temperatures higher than 110 °C.   α was reaching a value of 1, implying   that no intersection point between the H–W line and the   Tm = Tc line could be obtained. (Tm is   the measured melting temperature and Tc is the   temperature at which the sample was crystallized). This   observation was corroborated by the crystallization line, which   was found to be parallel to the melting line for Tc >   110 °C. We relate these changes in slope to different   stabilization mechanisms of the secondary nuclei at the growth   front of polymer lamellar crystals. For Tc > 110 °C,   secondary nuclei are proposed to be stabilized by coalescence of   neighboring nuclei, all having a small width. By contrast, for   Tc > 110 °C, the number density of secondary nuclei   is low and thus their coalescence is rare. Accordingly, nuclei   are stabilized by growing in size, mainly increasing their width.

      Address (URL): pubs.acs.org/doi/abs/10.1021/acs.macromol.5b02123