Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 1 Introduction
- 2 Some physical techniques for studying polymers
- 3 Molecular sizes and shapes and ordered structures
- 4 Regular chains and crystallinity
- 5 Morphology and motion
- 6 Mechanical properties I – time-independent elasticity
- 7 Mechanical properties II – linear viscoelasticity
- 8 Yield and fracture of polymers
- 9 Electrical and optical properties
- 10 Oriented polymers I – production and characterisation
- 11 Oriented polymers II – models and properties
- 12 Polymer blends, copolymers and liquid-crystal polymers
- Appendix: Cartesian tensors
- Solutions to problems
- Index
11 - Oriented polymers II – models and properties
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 1 Introduction
- 2 Some physical techniques for studying polymers
- 3 Molecular sizes and shapes and ordered structures
- 4 Regular chains and crystallinity
- 5 Morphology and motion
- 6 Mechanical properties I – time-independent elasticity
- 7 Mechanical properties II – linear viscoelasticity
- 8 Yield and fracture of polymers
- 9 Electrical and optical properties
- 10 Oriented polymers I – production and characterisation
- 11 Oriented polymers II – models and properties
- 12 Polymer blends, copolymers and liquid-crystal polymers
- Appendix: Cartesian tensors
- Solutions to problems
- Index
Summary
Introduction
In this chapter an attempt to answer the following questions is made.
(i) What kind of theoretical models, or deformation schemes can be envisaged for predicting the distribution of molecular orientations in a drawn polymer?
(ii) How do the predictions of these models agree with experimental results for the orientation averages such as 〈P2(cos θ)〉?
(iii) How can experimental or theoretical values of the orientation averages be used to predict the properties of the drawn polymer and with how much success?
These questions form the topics of discussion for sections 11.2, 11.3 and 11.4, respectively. In extremely highly drawn material, a great deal of modification of the original structure of the polymer must have taken place and most of the chains are essentially parallel to the draw direction, so that 〈cos2 θ〉 and 〈P2(cos θ)〉 are both close to 1. It is difficult to describe theoretically and in detail how molecular orientation takes place under these circumstances and thus to predict the small departures from unity for such materials. Discussion of the prediction and use of orientation averages is therefore limited to materials of moderate draw ratios. Models used for interpreting the properties of highly oriented polymers are discussed in sections 11.5 and 11.6.
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- Chapter
- Information
- An Introduction to Polymer Physics , pp. 321 - 342Publisher: Cambridge University PressPrint publication year: 2002