SURFACE ORIENTATION IN THE SHEET OF A LIQUID-CRYSTALLINE POLY(ESTER AMIDE) CHARACTERIZED BY REFLECTION INFRARED-SPECTROSCOPY

Polarized reflection infrared spectroscopy was applied to characterize the surface orientation of extrusion molded sheets of a liquid crystalline poly(ester amide) polymerized from 2-hydroxy-6-naphthoic acid, 4-aminophenol, and terephthalic acid. One of the spectroscopic methods studied in this work is specular reflection infrared spectroscopy, in which the absorption and refractive indices are calculated from the specular reflectance by using the Fresnel equation and the Kramers-Kronig relation. Another technique used for the analysis is polarized ATR spectroscopy, which gives the three-dimensional components of the absorption index. The polarized ATR spectrum is in excellent agreement with the spectrum obtained from the specular reflection measurement in the spectral region where only weak absorption bands exist. Intense absorption bands in the ATR spectrum are, however, influenced by the large refractive index dispersion. At a lower draw-down ratio, the surface orientation function is higher than the bulk orientation function obtained from the azimuthal intensity distribution of wide-angle X-ray diffraction. The bulk orientation function increases with increasing draw-down ratio, and the difference between the surface and bulk orientation functions is smaller at higher draw-down ratio.