Orientation Evolution in Convergent-Divergent Dies
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J. Zhao
Abstract
Solid-state extrusion experiments were carried out through constant area convergent-divergent dies using two crystalline polymers, i.e. ultra high molecular weight polyethylene (UHMWPE) and polytetrafluorethylene (PTFE), with the aim of producing extrudates exhibiting biaxial orientation. The evolution of orientation was examined along the extrusion axis by measuring the off-plane birefringence values at various distances from the entry on specimens removed from the dies. Simple analytical expressions relating orientation factor to draw ratio in the three mutually perpendicular directions were derived for crystalline polymers. These generalised relationships were found applicable for all types of deformations, i.e. monoaxial, biaxial and pure shear. On the basis of the data obtained and the predictions from the theoretical analysis, the deformations taking place in dies with small converging angles, known as fish-tail dies, were found to be close to a state of pure shear deformations, while dies with high converging angles initially, then changing to high divergencies in the second section, known as dual-taper dies, were found to give rise to a state of unbalanced biaxial deformations.
© 1994, Carl Hanser Verlag, Munich
Articles in the same Issue
- Contents
- Contents
- Editorial
- Ninth in a Series: Mitsubishi Heavy Industries: Road to a High Technology Giant
- Internal Mixers
- Two-Dimensional Dynamic Study of the Distributive Mixing in an Internal Mixer
- Screw Extrusion
- Design of Tightly Intermeshing Co-Rotating Twin Screw Extruders
- Devolatilization of Polymer Solutions
- Flow Mechanisms, Material Distributions and Phase Morphology Development in a Modular Intermeshing Counter-Rotating Twin Screw Extruder of Leistritz Design
- 3-D Flow Simulations of a Cavity Transfer Mixer
- Die Extrusion
- Flow and Fiber Orientation Calculations in Reinforced Thermoplastic Extruded Tubes
- Fiber Spinning
- Orientation Evolution in Convergent-Divergent Dies
- Molding
- Unsteady Flow of Semi-Concentrated Fiber Suspensions in Compression Molding
- Equation of State for Pure Polymeric Fluids Theory Based on An Improved Hole and Cell Model
- Residual Stresses in Quenched and Injection Moulded Products
- Image Simulation and Evaluation of Fiber Orientation Distribution
Articles in the same Issue
- Contents
- Contents
- Editorial
- Ninth in a Series: Mitsubishi Heavy Industries: Road to a High Technology Giant
- Internal Mixers
- Two-Dimensional Dynamic Study of the Distributive Mixing in an Internal Mixer
- Screw Extrusion
- Design of Tightly Intermeshing Co-Rotating Twin Screw Extruders
- Devolatilization of Polymer Solutions
- Flow Mechanisms, Material Distributions and Phase Morphology Development in a Modular Intermeshing Counter-Rotating Twin Screw Extruder of Leistritz Design
- 3-D Flow Simulations of a Cavity Transfer Mixer
- Die Extrusion
- Flow and Fiber Orientation Calculations in Reinforced Thermoplastic Extruded Tubes
- Fiber Spinning
- Orientation Evolution in Convergent-Divergent Dies
- Molding
- Unsteady Flow of Semi-Concentrated Fiber Suspensions in Compression Molding
- Equation of State for Pure Polymeric Fluids Theory Based on An Improved Hole and Cell Model
- Residual Stresses in Quenched and Injection Moulded Products
- Image Simulation and Evaluation of Fiber Orientation Distribution
