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Articolo in rivista, 2024, ENG, 10.1016/j.polymer.2023.126659

Coexistence of two lamellar populations in poly(ethylene vanillate) reorganized upon heating

Maria Cristina Righetti, Paola Marchese, Dario Cavallo, Annamaria Celli, Carla Marega

CNR-IPCF, National Research Council - Institute for Chemical and Physical Processes, Via Moruzzi 1, 56124, Pisa, Italy Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Via Terracini 28, 40131, Bologna, Italy Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 3, 16146, Genova, Italy Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy

The structural evolution of poly(ethylene vanillate) (PEV) crystals, after isothermal crystallization at Tc = 180 oC, was explored by synchrotron wide-angle and small-angle X-ray scattering (WAXS and SAXS) measurements. The WAXS/SAXS analyses proved that an additional more perfect crystal population starts to grow exactly in correspondence of the exotherm displayed by the specific heat capacity curve. The study ascertained that two different reorganization/recrystallization mechanisms occur upon heating: the more perfect crystals originate from a recrystallization process, whereas the original crystals undergo small and progressive perfection maybe without previous complete fusion. Deconvolution of the double Lorentz-corrected SAXS profiles was performed to calculate the temperature evolution of the lamellar thickness for the original and additional crystal populations. The two crystal populations appear to differ substantially in the temperature evolution of the lamellar and amorphous thicknesses. Hypotheses on the relative location of the two different crystal stacks as well as on the possible thermodynamic reason that triggers the formation of the more perfect crystal population have been formulated.

Polymer (Guildford) 293 , pp. 126659–?