The bridges of understanding

The objective of this book is to build bridges of understanding between, on one hand, the chemical structure of polymer molecules and, on the other, the macroscopic technological or engineering behaviour of a plastic or rubber material. We have opted to do this by way of consideration of molecular behaviour, and particularly of the molecular movement and the morphology of the material. By understanding how chemical structure determines the characteristics of molecular motion and morphology, and how these in turn influence the bulk properties, we can link chemistry to materials science in a smooth and informative way. 

Molecular structure Structure determination Molecular energies 

Translation, internal rotation Reptation, normal modes 

There are two inter-related ways to build this link. We start by asking, What are the molecules doing The answer, of course, is, The molecules are moving (or not moving). So we foUow that up by asking, Why are they moving How are they moving What controls the movement What are the consequences of the movement  

The second way to construct this link is to consider how the structure of the molecules gives rise to crystalhnity or other two-phase behaviour, then to examine how the dynamic properties of the morphology link to the physical behaviour. The phase behaviour is a reflection of the balance between the inter- and intra-atomic interactions which determine how easily molecules pack together and also how easily they are able to change their shape. 

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In this chapter, the ordered structures that can be found in certain polymer solids are considered. As as presented in Chapter 1, the understanding of the phase morphology of a material is an essential component of the bridges of understanding between chemical structure and physical properties. In addition, the morphology is intimately connected with the various phenomena of molecular motion. Some consequences of this will be developed further in Chapter 9. 

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