I. Koprinarov et al., SURFACE-ANALYSIS OF DC OXYGEN PLASMA-TREATED OR CHROMIUM EVAPORATED POLY(ETHYLENE-TEREPHTHALATE) FOILS BY SOFT-X-RAY ABSORPTION-SPECTROSCOPY (NEXAFS), Polymer, 38(8), 1997, pp. 2005-2010
Surface modified biaxially stretched poly(ethylene terephthalate) (PET
) foils have been analysed by surface sensitive soft X-ray absorption
(NEXAFS) spectroscopy. Generally, an orientation of polymer chain segm
ents can be detected by a variation of the angle between the linearly
polarized synchrotron light beam and the surface normal of the investi
gated sample (angle resolved NEXAFS spectroscopy). Biaxially stretched
PET foils have been found to be characterized by angle dependent NEXA
FS C and O K-edge spectra. This angle dependence was interpreted to be
a result of a preferential orientation of the PET chain segments at t
he surface wherein the plane defined by the benzene ring is parallel t
o the surface plane. In the course of chromium deposition or low press
ure O-2 DC plasma treatment that preferential orientation is continuou
sly diminished. This is interpreted to be a structural effect of the r
espective treatment. (C) 1997 Elsevier Science Ltd.