Moving Towards Reality From Order to Disorder

9 Moving Towards Reality From Order to Disorder 

In reality, polymeric materials never possess the perfect chemical stereochemical and conformational regularity which were assumed at the beginning of Section 3.5. 

In polymer material science it is essential to know the detailed independent structural characteristics (and the relative concentrations) of the crystalline and amorphous (or irregular) fractions of a polymer sample. All mechanical, viscoelastic or, in general, tlie physical properties of real polymeric materials depend on the relative fraction of crystalline versus non crystalline material. 

Since the spectroscopic manifestations of molecular disorder are many and very characteristic, the vibrational spectrum has become a useful probe for molecular order-disorder which can be described at the level of a few Angstroms. 

Spectroscopists are asked to find ways to account for the new spectral features associated to disorder, thus making vibrational spectra useful for the practical structural characterization of a real polymer material. Obviously, the theories presented in the previous sections of this chapter must be adapted or re-worked in order to understand the spectra of disordered organic polymers. 

---