Dynamics and Stability of Double Bubble Tubular Film Extrusion
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H. J. Kang
Abstract
A basic study of the kinematics and dynamics of the double bubble tubular film process as applied to polyethylene terephthalate (PET), poly p phenylene sulfide (PPS), polycarbonate (PC) and low density polyethylene (LDPE) is presented. The stability of the four resins was investigated for both a single bubble tubular film and a second bubble of a double bubble process. For the single bubble the LDPE is very stable and the PET, PPS and PC have more limited regions of stability with periodic axisymmetric instabilities near blowup ratios of unity and helical instabilities at higher blowup ratios. It is found that in the first bubble the PC vitrifies to a glass, PET and PPS crystallize to 4 to 9% levels and LDPE to nearly 50%. In the second bubble it is found possible to operate in a stable manner with a heated air ring and stable bubble for PET and PPS but not PC and LDPE. In the second bubble PET and PPS show substantial levels of increase of crystallinity. This is not the case for PC and LDPE. It appears that a strain hardening process such as crystallization is necessary for stability of the second bubble. Stress fields in the second bubble are computed using membrane theory.
© 1992, Carl Hanser Verlag, Munich
Articles in the same Issue
- Contents
- Contents
- Internal and Continuous Mixers
- Model Development for an Internal Mixer
- Simulation of Flow in a Farrel Continuous Mixer
- Extrusion
- Influence of Process Data on the Throughput of Large Extruders within the Range of 600 to 6 000 kg/h
- Conveying and Melting in Screw Extruders with Axial Screw Movement
- Thermo-viscous Effects in Extrusion of Planar Jets with Solidification
- Film
- Dynamics and Stability of Double Bubble Tubular Film Extrusion
- Melt Strength Behavior of Polyethylene Blends**
- Optical Properties and Orientation Development in Uniaxially Stretched Syndiotactic Polystyrene from Amorphous Precursors
- Molding
- Thermoviscoelastic Calculation of Residual Stresses and Residual Shapes of Injection Molded Parts**
- Analysis and Simulation of Structural Reaction Injection Molding (SRIM)
- Crystal Orientation in Injection Moldings of Flaky Filler-Filled Polypropylenes
- Erratum
- Molecular Orientation in Injection-molded Polypropylene Copolymers with Ethylene
Articles in the same Issue
- Contents
- Contents
- Internal and Continuous Mixers
- Model Development for an Internal Mixer
- Simulation of Flow in a Farrel Continuous Mixer
- Extrusion
- Influence of Process Data on the Throughput of Large Extruders within the Range of 600 to 6 000 kg/h
- Conveying and Melting in Screw Extruders with Axial Screw Movement
- Thermo-viscous Effects in Extrusion of Planar Jets with Solidification
- Film
- Dynamics and Stability of Double Bubble Tubular Film Extrusion
- Melt Strength Behavior of Polyethylene Blends**
- Optical Properties and Orientation Development in Uniaxially Stretched Syndiotactic Polystyrene from Amorphous Precursors
- Molding
- Thermoviscoelastic Calculation of Residual Stresses and Residual Shapes of Injection Molded Parts**
- Analysis and Simulation of Structural Reaction Injection Molding (SRIM)
- Crystal Orientation in Injection Moldings of Flaky Filler-Filled Polypropylenes
- Erratum
- Molecular Orientation in Injection-molded Polypropylene Copolymers with Ethylene
