Schreiber, R.; Veeman, W.s.; Gabrieelse, W.; Arnauts, J.:

NMR Investigations of Orientational and Structural Changes in Polyamide-6 Yarns by Drawing.

In: Macromolecules (Macromolecules), Jg. 32 (1999) ; Nr. 14, S. 4647-4657
ISSN: 0024-9297
Zeitschriftenaufsatz / Fach: Chemie
Abstract:
The effect of drawing on the structure and mol. orientation of polyamide-6 fibers has been investigated by 13C solid-state NMR. The mol. orientation in the fibers is detd. using a two-dimensional rotor synchronized magic-angle spinning (MAS) expt. For the highly oriented fibers order parameters up to {P6} are detd. By using a 13C T1r filter, the orientation in the rigid (cryst. + rigid amorphous) and mobile (amorphous) regions are sep. detd. The orientation in the rigid phase increases rapidly at low draw ratios up to l = 3.5 and levels off at higher draw ratios ({P2} ~ 0.75). The mobile amorphous phase remains disordered for low draw ratios but orients rapidly for draw ratios above l = 3.5. By using a 13C T1 filter, 13C MAS spectra of the cryst. phase are obtained, from which the relative amts. of the a- and g-phase can be quant. detd. using spectral deconvolution. It appears that upon drawing, the a/g ratio changes from 60/40 for an undrawn fiber to almost completely a for a fully drawn fiber. The NMR results are qual. supported by wide-angle X-ray spectroscopy (WAXS) photos.