| Abstract: | The techniques of polarized infrared spectroscopy and sample tilting are applied to one-way drawn poly(ethylene terephthalate) (PET) films to calculate the trichroic absorption as a function of frequency. Of specific interest in this study is the distribution of vibrational modes in the plane transverse to the draw direction. The rotational isomeric content of the films is found by the method of least squares and compared with a density-method prediction of crystallinity. A two-phase model to describe PET morphology in the oriented state is examined and found to be inadequate. The segmental orientation as a function of strain is followed with five conformationally sensitive infrared modes. High segmental orientation is found in the trans conformers of both amorphous and crystalline phases. Little net segmental orientation in the gauche conformers of the amorphous phase occurs. |
