Experimental determination of the fiber orientation parameters and the Raman tensor of the 1614 cm(-1) band of poly(ethylene terephthalate)

Polarized Raman spectroscopic measurements were performed on uniaxially ori ented fibers of poly(ethylene terephthalate). The diagonal Raman tensor for the 1614 cm(-1) band along with the second- and fourth-order coefficients of the orientation distribution function are determined from the Raman scat tering intensities as a function of spin-speed. The development of an orien ted-amorphous material within the fiber is explained. The elements of the R aman tensor appear to vary as a function of spinning speed. This observatio n calls into question the use of isotropic values for the Raman tensor when determining the orientation. (C) 2000 Elsevier Science B.V. All rights res erved.