External Calibration in PA12 Tube Extrusion
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A. Carin
Abstract
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.
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© 2006, Hanser Publishers, Munich
Articles in the same Issue
- Contents
- Contents
- Editorial
- Dedication of the Special Issue of International Polymer Processing in Honor of Prof. James Lindsay White, Editor Emeritus and Founding Editor
- Invited Papers
- Melt Compounding of Polymeric Nanocomposites
- Experiments and Analysis of Effect of Calender Gaps on Melting of PVC Powders in an Intermeshing Counter-rotating Twin-screw Extruder
- Quantitative Analysis for Polymer Degradation in the Extrusion Process
- Visualization of Flow Instabilities for High Density Polyethylene
- Heat Transfer through Metal Walls of Finite Thickness
- Simulation and Experimental Verification of Crystallization and Birefringence in Melt Spinning of PET
- Structural Development and Properties of Melt Spun Poly(butylene succinate) and Poly(butylene terephthalate-co-succinate-co-adipate) Biodegradable Fibers
- External Calibration in PA12 Tube Extrusion
- Tubular Film Extrusion Stability of Metallocene Linear Low Density Polyethylene
- Multilayer Barrier Film of Biaxially Oriented PA6/EVOH by Double Bubble Tubular Film Process
- PPS News
- PPS News
- Seikei-Kakou Abstracts
- Seikei-Kakou Abstracts
Articles in the same Issue
- Contents
- Contents
- Editorial
- Dedication of the Special Issue of International Polymer Processing in Honor of Prof. James Lindsay White, Editor Emeritus and Founding Editor
- Invited Papers
- Melt Compounding of Polymeric Nanocomposites
- Experiments and Analysis of Effect of Calender Gaps on Melting of PVC Powders in an Intermeshing Counter-rotating Twin-screw Extruder
- Quantitative Analysis for Polymer Degradation in the Extrusion Process
- Visualization of Flow Instabilities for High Density Polyethylene
- Heat Transfer through Metal Walls of Finite Thickness
- Simulation and Experimental Verification of Crystallization and Birefringence in Melt Spinning of PET
- Structural Development and Properties of Melt Spun Poly(butylene succinate) and Poly(butylene terephthalate-co-succinate-co-adipate) Biodegradable Fibers
- External Calibration in PA12 Tube Extrusion
- Tubular Film Extrusion Stability of Metallocene Linear Low Density Polyethylene
- Multilayer Barrier Film of Biaxially Oriented PA6/EVOH by Double Bubble Tubular Film Process
- PPS News
- PPS News
- Seikei-Kakou Abstracts
- Seikei-Kakou Abstracts
