Refractive indices along the three principal directions of uniaxial planar deformed poly(ethylene terephthalate) (PET) films have been used to calculate the second moments of the orientation distribution of the phenyl ring's normal with respect to the three principal directions of the sample. Under our stretching conditions, the phenyl rings show a strong tendency to orient their plane parallel to the plane of the films. The orientation of the chain axis can also be evaluated from the same data. A good correlation is observed between this indirect measurement and direct, but more tedious, techniques such as infra-red dichroism.
Посилання на статтю:
Uniaxial planar deformation of PET films: 2. Characterization of the orientation from measurements of refractive indices / P. Lapersonne and J. F. Tassin* // Polymer. – 1994. – Vol 35. – P. 2192-2196.