A thermomechanical analysis of yarns in a tensile mode is used to characterize wool fibers modified to show the β-crystal form in comparison with native untreated wool retaining the α-crystal form. The TMA curves show that fiber extension causes significant structural modification of the wool samples. In particular, melting of the α-form crystallites in native wool can be detected at around 215°C, with supercontraction prior to effective crystallite melting. But extended wool yarn shows no thermal mechanical event corresponding to melting of the β-form crystallites. Extended wool has a thermal mechanical behavior similar to that of silk yarn.
Get full access to this article
View all access options for this article.
References
1.
1. Annual Book of ASTM Standards, vol. 04.04, pp. 359–367, 1987.
2.
2. Bendit, E. G., Melting of α-Keratin in Vacuo, Textile Res. J.36, 580–581 (1966).
3.
3. Bhoyro, A. Y., Cook, J. R., Hillbrick, L. K., Liddicoat, B. E., O'loughin, G. J., Phillips, D. G., and Robinson, G. A., Modified Wool Fibres for New Apparel Products, in “Proc. 4th Asian Textile Conference,” Taipei, June 24-26, 1997, pp. 999-1005.
4.
4. Cao, J., A Weight Averaged NMR Spin-Spin Relaxation Time Constant and Its Determination, J. Magnet. ResonanceB33, 567–569 (1994).
5.
5. Cao, J., Origin of the Bimodal ‘Melting’ Endotherm of α-form Crystallites in Wool Keratin, J. Appl. Polym. Sci.63, 411–415 (1997).
6.
6. Cao, J., Melting Study of the α-form Crystallites in Human Hair Keratin by DSC, Thermochim. Act.335, 5–9 (1999).
7.
7. Cao, J., and Billows, C. A., Crystallinity Determination of Native and Stretched Wool by X-ray Diffraction, Polym. Int. (in press).
8.
8. Cao, J., Buckley, A. N., and Lynch, L. J., Measurement of an Intrinsic Softening Temperature of Coal-tar Pitch, Carbon32, 493–497 (1994).
9.
9. Cao, J., Chatfield, S. P., and Saxby, J. D., A Thermomechanical Technique for Characterizing Pitch, J. Therm. Anal.44, 281–291 (1995).
10.
10. Cao, J., Joko, K., and Cook, J. R., DSC Studies of the Melting Behavior of α-Form Crystallites in Wool Keratin, Textile Res. J.67, 117–123 (1997).
11.
11. Church, J. S., Corino, G. L., and Woodhead, A. L., The Effects of Stretching on Wool Fibres as Monitored by FT-Raman Spectroscopy, J. Molec. Struct.440, 15–23 (1998).
12.
12. Feughelman, M., and Mitchell, T. W., The Melting of α-Keratin in Water, Textile Res. J.36, 578–579 (1966).
13.
13. Gedde, U. W., “Polymer Physics,” Chapman & Hall, London, 1995.
14.
14. Haly, A. R., and Snaith, J. W., Differential Thermal Analysis of Wool—The Phase Transition Endotherm under Various Conditions, Textile Res. J.37, 898–907 (1967).
15.
15. Magoshi, J., and Nakamura, S., Studies on Physical Properties and Structures of Silk-Glass Transition and Crystallization of Silk Fibrion, J. Appl. Polym. Sci.19, 1013–1015 (1975).
16.
16. Magoshi, J., and Nakamura, S., Structure and Thermal Analysis of Silk, Netsu Sokutei (Thermal Measurements, Japan)14, 58–69 (1987).
17.
17. Mark, J. E., Physical Properties of Polymers, ACS Professional Reference Book, American Chemical Society, Washington, D.C., 1993.
18.
18. Menefee, E., and Yee, G., Thermal-Induced Structural Changes in Wool, Textile Res. J.35, 801–812 (1965).
19.
19. Nakamura, S., and Magoshi, J., Thermal Properties of Silk Proteins in Silkworms, ch. 19 in ACS Symposium Series 544 D. Kaplan et al., Eds., American Chemical Society, Washington, D.C., 1994.
20.
20. Webster, D. S., and Cao, J., A Novel Technique for Characterising Polymeric Materials—Proton Magnetic Resonance Thermal Analysis, Curr. Trends Polym. Sci.1, 147–155 (1996).
21.
21. Wunderlich, B., “Thermal Analysis,” Academic Press Inc., San Diego, CA, 1990.
