Crystallite orientation in wool fibers

Abstract

The main features of the wide angle X-ray patterns in wool are': meridional a-arc associated with group of reflections at about 0.51 nm (28 = 17.8"), the equatorial spot at 0.465 nm (28 = 19" ) associated with @-form, and the equatorial spot at 0.98 nm (28 = 9") common to both a-and @-forms. The various reflections observed in the X-ray patterns indicate good crystallite orientation in the direction of fiber axis.Wools of different biological origin are known to show differences in their properties, which, in turn, are related to differences in the structure and morph~logy.~-~ The birefringence values of three different wools, namely Merino, Chokla, and Lincoln, have been shown to correlate well with their morphology and various physical pr0perties.3.~ Birefringence in wool arises predominantly from its crystallites, and their orientation is therefore of considerable interest. However, there is hardly any reported study on the changes in crystallite orientation as related to such differences. In the present work, the X-ray diffraction

Self-assembly behavior of the keratose proteins extracted from oxidized Ovis aries wool fibers

“…However, acid hydrolysis of a wool sample using 4 N HCl at high temperature yielded amorphous structure [20]. The peak at 20°corresponds to β-sheet structure whereas the other peak at 9°represents both α-helical and β-sheet conformations of the proteins [38,39]. No significant difference was observed between relative intensities of these two peaks for the oxidized wool and the keratose indicating that no detectable conformational changes occurred during the extraction of the keratoses from the oxidized wool.…”

“…The first endotherm observed at ~75 ± 3 °C corresponded to removal of moisture and volatile materials which constitutes ~6.5-7% of the total weight of the samples. The second endotherm was obtained between 200 °C and 400 °C mainly indicating the degradation of the side chains of the proteins [39,44,47]. In this region, the corresponding weight losses were 36%, 37%, and 45% for the defatted wool, the oxidized wool and the keratose respectively.…”

Highly efficient extraction of large molecular-weight keratin from wool in a water/ethanol co-solvent

“…Generally, the a-helix structure and b-sheet structure are indexed to peaks at 9 and 17.8 , and 9 and 19 respectively. 14,36 The XRD pattern of extracted keratin showed movement to a low angle region of peaks at both 8.6 and 19.6 when compared with natural wool (9.8 and 20.9 ). 37 The a-helical structure is tightly connected with a large number of disulfide bonds.…”

Green process to regenerate keratin from feathers with an aqueous deep eutectic solvent

“…The diffraction spot at 5.1Å (2q ¼ 17.8 ) is associated with a-helix, the spot at 4.65Å (2q ¼ 19 ) with b-sheet, and the spot at 9.8Å (2q ¼ 9 ) with both ahelix and b-sheet. 35,56 Due to the tight overlapping of a-helix and b-sheet, their unambiguous assignment to individual components is not possible. However, deconvolution of crystalline and amorphous intensity proles could be carried out in order to determine the portion of crystallinity in the samples (Fig.…”