In-situ SAXS/WAXS investigations of the mechanically-induced phase transitions in semi-crystalline polyamides

Abstract : The structural evolution under uniaxial tension of both Polyamide-11 (PA11) and Polyamide-6 (PA6) crystallized under various crystal forms has been investigated as a function of draw temperature with respect to the Brill transition. The use of in-situ synchrotron two-dimensional wide-angle X-ray diffraction and small-angle X-ray scattering allows to discriminate thermal from mechanical effects, leading to a revisited scheme of the strain-induced phase transitions in polyamides. It is demonstrated that only the H-bonded sheet-like structures transform mechanically into a pseudo-hexagonal form with a random distribution of H bonds around the chain axis. This order-disorder transition occurs during the fibrillar transformation and seems systematically preceded by a twinning mechanism at low deformation. By contrast, the mesophases and the High Temperature forms are mechanically stable, the latter transforming thermally into the H-bonded sheet-like structures as soon as samples are cooled down below the Brill transition temperature.
Type de document :
Article dans une revue
Liste complète des métadonnées

https://hal.univ-lille.fr/hal-02448905
Contributeur : Lilloa Université de Lille <>
Soumis le : mercredi 22 janvier 2020 - 15:27:07
Dernière modification le : mercredi 19 février 2020 - 14:43:23

Identifiants

Collections

Citation

Julie Pepin, Valérie Gaucher, Cyrille Rochas, Jean-Marc Lefebvre. In-situ SAXS/WAXS investigations of the mechanically-induced phase transitions in semi-crystalline polyamides. Polymer, Elsevier, 2019, Polymer, pp.87-98. ⟨10.1016/j.polymer.2019.04.073⟩. ⟨hal-02448905⟩

Partager

Métriques

Consultations de la notice

8