Relationship of Stresses in Blown-film Processes
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S. J. Kurtz
Abstract
Fabrication conditions and material rheology control the process of film blowing and limit the possible shapes the bubble may take as well as the ranges and ratios of stresses within the bubble. In order to understand bounds on the stresses during the blowing process, we explore the constraints imposed by force balances, the thin shell approximation, and thermodynamics. We show that the ratio of axial stress to hoop stress is independent of the explicit terms for film thickness, velocity, heat transfer, and the rheology of the material. In addition, we demonstrate that the ratio of the axial stress to the hoop stress can be calculated at any point in the blown-film requiring only values for the pressure drop across the bubble, the shape of the bubble, and the force pulling up the bubble. Experimental results, as well as certain theoretical evidence, strongly indicate that the ratio of axial to hoop stress is everywhere greater than 1 in the standard blown-film process. If this is generally true, then the stress relations we derived can be employed to test the applicability of various theoretical models of the blown-film process.
© 1995, Carl Hanser Verlag, Munich
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- Fourteenth in a Series: Pomini SpA: Dynamic International Machinery Manufacturer
- Internal Mixers
- Non-isothermal Dispersive Flow of a Rubber Mixture Inside an Internal Rotor Mixer
- Screw Extrusion/Continuous Mixing
- Solids Conveying and Melting in a Starve Fed Self-wiping Co-rotating Twin Screw Extruder
- Modeling the Residence Time Distribution of a Non-Intermeshing Twin Screw Extruder
- Mixing Ring
- Morphology in Blends of a Thermotropic Liquid Crystalline Polymer and Polypropylene
- Die Extrusion
- Mechanical Effects in Extrusion: Slit Dies
- Fibers and Films
- Relationship of Stresses in Blown-film Processes
- Molding
- Modelling and Experiments of Squeezing Flow of Polymer Melts
- Crystallization Behavior of Carbon Fiber Reinforced Polyamides (I) Dynamic and Isothermal Crystallization
- Structures and Properties of Injection Moldings of β-Crystal Nucleator-Added Polypropylenes
- Forging
- Numerical Simulation of Polymer Forging
- Rapid Communication of Recent Advances
- Unstable Gas Penetrations in Symmetrical Rib Channels During Gas-assisted Injection Molding
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- Fourteenth in a Series: Pomini SpA: Dynamic International Machinery Manufacturer
- Internal Mixers
- Non-isothermal Dispersive Flow of a Rubber Mixture Inside an Internal Rotor Mixer
- Screw Extrusion/Continuous Mixing
- Solids Conveying and Melting in a Starve Fed Self-wiping Co-rotating Twin Screw Extruder
- Modeling the Residence Time Distribution of a Non-Intermeshing Twin Screw Extruder
- Mixing Ring
- Morphology in Blends of a Thermotropic Liquid Crystalline Polymer and Polypropylene
- Die Extrusion
- Mechanical Effects in Extrusion: Slit Dies
- Fibers and Films
- Relationship of Stresses in Blown-film Processes
- Molding
- Modelling and Experiments of Squeezing Flow of Polymer Melts
- Crystallization Behavior of Carbon Fiber Reinforced Polyamides (I) Dynamic and Isothermal Crystallization
- Structures and Properties of Injection Moldings of β-Crystal Nucleator-Added Polypropylenes
- Forging
- Numerical Simulation of Polymer Forging
- Rapid Communication of Recent Advances
- Unstable Gas Penetrations in Symmetrical Rib Channels During Gas-assisted Injection Molding
