W. Gabrielse et al., MOLECULAR-ORIENTATION IN DIFFERENTLY PROCESSED POLY(ETHYLENE-TEREPHTHALATE) YARNS AS STUDIED BY C-13 2D CP-MAS NMR, Macromolecules, 29(11), 1996, pp. 4125-4133
The molecular orientation of a series of differently processed industr
ial fibers of poly(ethylene terephthalate) (PET) has been investigated
by C-13 solid-state rotor-synchronized 2D CP-MAS NMR.(1) In addition
to the [P-2] order parameters, higher rank order parameters, [P-4] and
[P-6], could also be determined. Significant differences in the order
parameters were observed as a function of the processing history. The
[P-2] order parameters obtained for the range of PET fibers showed a
linear relationship with the optical birefringence data. By making plo
ts of the [P-4]/[P-2] and [P-6]/[P-2] ratios corresponding with severa
l types of distributions using a Pearson VII function, the orientation
distribution was reconstructed. For the as-spun fibers, relatively hi
gh [P-4]/[P-2] and [P-6]/[P-2] ratios were obtained which points to a
heavily tailed orientation distribution. The order parameters of the d
rawn PET fibers agree quite well with the pseudoaffine deformation mod
el.