Interpretation of the structure of poly(ethylene terephthalate) by dynamic FT-IR spectra

Poly(ethylene terephthalate) (PET) was studied by the technique called dynamic infrared spectroscopy with the use of digital signal processing. The dynamic infrared signals of PET were correlated with the reorientation movement of Functional groups and the deformation of internal coordinates, which depend upon the morphology of the sample. With the use of this novel approach, it is demonstrated that the internal coordinate change of the trans C-O bond plays an important role in the macroscopic deformation of oriented PET; the reorientation movement is differentiated in the case of unoriented PET, where the phenyl ring contributes more in such a process.