화학공학소재연구정보센터
Macromolecules, Vol.32, No.14, 4647-4657, 1999
NMR investigations of orientational and structural changes in polyamide-6 yarns by drawing
The effect of drawing on the structure and molecular orientation of polyamide-g fibers has been investigated by C-13 solid-state NMR. The molecular orientation in the fibers is determined using a two-dimensional rotor synchronized magic-angle spinning ((MAS) experiment. For the highly oriented fibers order parameters up to (Ps) are determined. By using a 13C Tip filter, the orientation in the rigid (crystalline + rigid amorphous) and mobile (amorphous) regions are separately determined. The orientation in the rigid phase increases rapidly at low draw ratios up to A = 3.5 and levels off at higher draw ratios ([P-2])approximate to 0.75). The mobile amorphous phase remains disordered for low draw ratios but orients rapidly for draw ratios above A = 3.5. By using a 13C TI filter, 13C MAS spectra of the crystalline phase are obtained, from which the relative amounts of the alpha- and gamma-phase can be quantitatively determined using spectral deconvolution. It appears that upon drawing the alpha/gamma ratio changes from 60/40 for an undrawn fiber to almost completely a for a fully drawn fiber. The NMR results are qualitatively supported by wide-angle X-ray spectroscopy (WAXS) photos.