A thermo-conductive approach to explain the origin of lamellar twisting in banded spherulites
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Thermo-conductive and morphological considerations have led to the conclusion that ribbon-like crystals developed in the presence of thermal gradients behave in the same manner of macroscopic cantilevers, whose deformation in a non uniform temperature field is a deeply examined issue in the continuum mechanics. Therefore, the well known concepts and principles of this science have been applied to a lower scale (Pitteri M, Zanzotto G (2002) Continuum models for phase transitions and twinning in crystals, CRC Press, London) to explain the origin of lamellar twisting during the growth of optically banded spherulites in polymer samples squashed between glass surfaces. The developed model considers that the torsional motion of the lamellae is caused by the presence of thermal gradients across the thickness of the samples and accounts for both morphological and optical characteristics of polymer spherulites.
KeywordsCrystallization Temperature Thermal Gradient Isotactic Polypropylene Torsion Moment Lamellar Thickness
The author would like to thank eng. B. Pascucci for the useful discussion on the mechanics of deformation of beam and for critical review of the manuscript.
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