External calibration in PA12 tube extrusion - Part II: Relations between molecular orientation, tensile properties and polymer drawing during calibration

Abstract : Elongation at break is one of the major end-use properties of polyamide 12 extruded tubes. It is strongly affected by the tube microstructure and the molecular orientation resulting from extrusion conditions. Molecular orientation was characterized by X-ray diffraction and birefringence evaluation in light microscopy. Measurements were carried out on (r z) sections obtained by polishing and microtoming. On the other hand, polymer drawing was measured on line by tracer techniques. Calibration stage was determined as the key step of the process that generates orientation in tubes: as the tube is drawn through a cylindrical calibrator under vacuum and cooled from its outside surface, calibration leads to a highly oriented zone in the twenty external microns. Calibration conditions and elongation at break have been connected through orientation level in this region. Molecular orientation was found to strongly depend on the draw ratio in the calibration tank. Finally, birefringence of the tube external layers and elongation at break were successfully correlated. Elongation at break can be enhanced by reducing orientation resulting from calibration conditions.
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https://hal-mines-paristech.archives-ouvertes.fr/hal-00574707
Contributeur : Magalie Prudon <>
Soumis le : mardi 8 mars 2011 - 16:12:20
Dernière modification le : jeudi 28 mars 2019 - 17:08:01

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  • HAL Id : hal-00574707, version 1

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Aurélien Carin, Jean-Marc Haudin, Michel Vincent, Bernard Monasse, Gaëlle Bellet, et al.. External calibration in PA12 tube extrusion - Part II: Relations between molecular orientation, tensile properties and polymer drawing during calibration. International Polymer Processing, 2005, 20 (3), pp.Pages 305-311. ⟨hal-00574707⟩

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