Laurie Shrage
- Published in print:
- 2003
- Published Online:
- November 2003
- ISBN:
- 9780195153095
- eISBN:
- 9780199870615
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/019515309X.003.0003
- Subject:
- Philosophy, Moral Philosophy
Evaluates “pro‐life” and “pro‐choice” media campaigns, featuring fetuses and coat hangers respectively, and shows how both reflect individualistic ideologies about responsibility and freedom. Rather ...
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Evaluates “pro‐life” and “pro‐choice” media campaigns, featuring fetuses and coat hangers respectively, and shows how both reflect individualistic ideologies about responsibility and freedom. Rather than participate in public discourses that construe individual responsibility and liberty as simple moral alternatives, considers feminist political art that raises questions about our collective responsibilities to support others. Also considers visual and performance artwork that draws attention to the way that pregnancy and persons are culturally constructed. Urges reproductive rights activists to jettison the coat hanger image in favor of images that would promote constructive public dialog on access to contraception, child and family support, the duties of all citizens to provide life‐saving help, the positive aspects of enabling women to control their fertility, and the dangers of religious extremism.Less
Evaluates “pro‐life” and “pro‐choice” media campaigns, featuring fetuses and coat hangers respectively, and shows how both reflect individualistic ideologies about responsibility and freedom. Rather than participate in public discourses that construe individual responsibility and liberty as simple moral alternatives, considers feminist political art that raises questions about our collective responsibilities to support others. Also considers visual and performance artwork that draws attention to the way that pregnancy and persons are culturally constructed. Urges reproductive rights activists to jettison the coat hanger image in favor of images that would promote constructive public dialog on access to contraception, child and family support, the duties of all citizens to provide life‐saving help, the positive aspects of enabling women to control their fertility, and the dangers of religious extremism.
Chang Dae Han
- Published in print:
- 2006
- Published Online:
- November 2020
- ISBN:
- 9780195187830
- eISBN:
- 9780197562369
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780195187830.003.0006
- Subject:
- Chemistry, Physical Chemistry
The flow geometry encountered in many polymer processing operations of industrial importance is often far more complex than that in cylindrical or slit dies. As will be shown in the following ...
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The flow geometry encountered in many polymer processing operations of industrial importance is often far more complex than that in cylindrical or slit dies. As will be shown in the following chapters, the industry manufactures polymeric products using very complex flow geometries. For instance, the fiber industry produces “shaped fibers,” which have cross sections that are noncircular. What is most intriguing in the production of shaped fibers is that a desired fiber shape is often produced by spinneret holes whose cross-sectional shape is quite different from that of the final fiber produced. Hence, an important question may be raised as to how one can determine, from a sound theoretical basis, the cross-sectional shape of spinneret holes that will produce a fiber with a desired cross-sectional shape. In extrusion and injection molding, a polymeric liquid invariably passes through a large cross section before entering into a small cross section, and such a flow is referred to as “entrance flow.” The entrance flow of polymeric liquids, due to their viscoelastic nature, is quite different from that of Newtonian liquids. Similarly, the flow behavior of viscoelastic polymeric liquids near the exit of a die, commonly referred to as “exit flow,” is quite different from that of Newtonian liquids. A better understanding of the unique characteristics of both entrance and exit flows of viscoelastic polymeric fluids is essential for successful design of extrusion dies and molds, as well as to solve difficult technical problems related to a particular processing operation. Before presenting specific polymer processing operations in following chapters, in this chapter we consider the flow of polymeric liquids through complex geometry: (1) fully developed flow through a rectangular channel with uniform channel depth; (2) fully developed flow through a rectangular channel with a moving channel wall; (3) flow through a rectangular channel with varying channel depth; (4) flow in the entrance region of a rectangular die having constant cross section; (5) flow through a tapered die; (6) flow in the exit region of a cylindrical or slit die; (7) flow through a slit die having side holes; and (8) flow through a coat-hanger die.
Less
The flow geometry encountered in many polymer processing operations of industrial importance is often far more complex than that in cylindrical or slit dies. As will be shown in the following chapters, the industry manufactures polymeric products using very complex flow geometries. For instance, the fiber industry produces “shaped fibers,” which have cross sections that are noncircular. What is most intriguing in the production of shaped fibers is that a desired fiber shape is often produced by spinneret holes whose cross-sectional shape is quite different from that of the final fiber produced. Hence, an important question may be raised as to how one can determine, from a sound theoretical basis, the cross-sectional shape of spinneret holes that will produce a fiber with a desired cross-sectional shape. In extrusion and injection molding, a polymeric liquid invariably passes through a large cross section before entering into a small cross section, and such a flow is referred to as “entrance flow.” The entrance flow of polymeric liquids, due to their viscoelastic nature, is quite different from that of Newtonian liquids. Similarly, the flow behavior of viscoelastic polymeric liquids near the exit of a die, commonly referred to as “exit flow,” is quite different from that of Newtonian liquids. A better understanding of the unique characteristics of both entrance and exit flows of viscoelastic polymeric fluids is essential for successful design of extrusion dies and molds, as well as to solve difficult technical problems related to a particular processing operation. Before presenting specific polymer processing operations in following chapters, in this chapter we consider the flow of polymeric liquids through complex geometry: (1) fully developed flow through a rectangular channel with uniform channel depth; (2) fully developed flow through a rectangular channel with a moving channel wall; (3) flow through a rectangular channel with varying channel depth; (4) flow in the entrance region of a rectangular die having constant cross section; (5) flow through a tapered die; (6) flow in the exit region of a cylindrical or slit die; (7) flow through a slit die having side holes; and (8) flow through a coat-hanger die.