External calibration in PA12 tube extrusion - Part II / A. Carin in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 3 (09/2005)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XX, N° 3 (09/2005) . - p. 305-311 Titre : External calibration in PA12 tube extrusion - Part II : Relations between molecular orientation, tensile properties and polymer drawing during calibration Type de document : texte imprimé Auteurs : A. Carin, Auteur ; Jean-Marc Haudin, Auteur ; M. Vincent, Auteur ; B. Monasse, Auteur ; G. Bellet, Auteur ; N. Amouroux, Auteur Année de publication : 2005 Article en page(s) : p. 305-311 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : 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. DOI : 10.3139/217.1892 En ligne : https://drive.google.com/file/d/1qlXg8n2kY0xo4rRrJc25AfYp6FZFHx1S/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3067 [article]

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External calibration in PA12 tube extrusion / A. Carin in INTERNATIONAL POLYMER PROCESSING, Vol. XXI, N° 1 (03/2006)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXI, N° 1 (03/2006) . - p. 70-80 Titre : External calibration in PA12 tube extrusion : Understand the influence of calibration on microstructure and surface state to improve mechanical properties Type de document : texte imprimé Auteurs : A. Carin, Auteur ; N. Amouroux, Auteur ; G. Bellet, Auteur ; B. Monasse, Auteur ; M. Vincent, Auteur ; Jean-Marc Haudin, Auteur Année de publication : 2006 Article en page(s) : p. 70-80 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : In polyamide 12 (PA12) tube extrusion, calibration is crucial for the major final properties such as elongation at break or burst pressure. In external calibration, the extruded tube is pulled through a cylindrical calibrator located in a water tank under vacuum. A water flow rate is applied at the calibrator inner side, creating a lubricating water layer at the polymer outer surface. A combination of a quenching and a mechanical drawing was highlighted during calibration by on-line measurements. A subsequent high molecular orientation in the outer tube layers was also featured by X-Ray diffraction and birefringence evaluation in light microscopy. Besides, influence of lubrication level in the sizing-sleeve was investigated by an estimate of the lubricating water layer and a characterization of the tube final surface state in different calibration conditions. Firstly, we quantitatively showed that rising the water layer thickness leads to a diminution of the draw ratio in the calibration tank, DrCAL (ratio between line velocity and velocity at the calibrator entrance). Excellent correlation has been found between tube superficial orientation and DrCAL: a reduced elongation of the polymer in the calibrator leads to a lower level of superficial orientation. Secondly, two kinds of surface defects were detected on the tubes by light microscopy and microtopography. At last, several correlations were featured with mechanical properties. Elongation at break was found to strongly depend on the molecular orientation resulting from calibration. Moreover, origin of rupture was investigated during tensile testing in light microscopy. We emphasized that surface defects alignments perpendicular to the extrusion initiate the rupture by creating a significant crack via coalescence of initial defects. Thus, microstructure, surface state and tensile properties can be controlled by fitting the calibration parameters to improve lubrication and reduce the draw ratio in calibrator. DOI : 10.3139/217.0066 En ligne : https://drive.google.com/file/d/1XqUDDzjm2hziXrE2HJSA4RY4NnYR4scR/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2931 [article]

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