Angular Characterization of Polymer Surfaces by FTIR ATR Dichroism with aRotatable Truncated Hemispheric Crystal

摘要

An attenuated total reflection attachment with a truncated hemispheric crystal ofKRS-5 and a goniometer sample holder was designed for FT IR instrument to obtain angular profiles of IR absorbances on polymer surfaces. The new optical set-up capable of five internal reflections with well defined incidence angles allows a full 360 deg rotation horizontally as well as some extent of depth profiling. Several polymer samples were used to demonstrate the capability of this attachment. First, films of undrawn, uniaxially drawn and biaxially drawn poly(ethylene terephthalate) (PET) were characterized using three IR bands at 972 cm -1, 899 cm-1 and 793 cm-1 . For uniaxially drawn PET, all the band intensities show peanut shape angular profiles, when plotted on a full 360 deg horizontal plane. The band at 972 cm-1 due to the trans conformer of the ethylene glycol unit exhibited much greater anisotropy along along the draw direction than the bands for the ganche conformer at 899 cm-1. For biaxial PET, the angular profiles of the band intensity become larger circles with increasing draw ratio, with the 972 cm-1 band showing the greatest increase. Independent results from x-ray diffraction Polymer surfaces, Angular absorbance, FT-IR ATR Dichroism, PET, PP, rolltrusion, counter-rotating die extrusion, truncated hemispheric crystal.