Depression of the melting temperature by moisture for alpha-form crystallites in human hair keratin.
DSC thermal analysis has been carried out for human hair samples with various moisture contents to investigate the melting temperature depression behavior of alpha-form crystallites in human hair. This is achieved by adopting a novel technique using silicon oil as the thermal medium, which permits hair samples to retain a range of moisture contents in between completely dry and fully saturated. The results show that the melting temperature of the alpha-form crystallites in human hair varies with moisture content from 205 degrees C for dry hair to 155 degrees C for the hair sample with moisture content of 23%. These experimental results are particularly useful for clarification of the conceptual ambiguities associated with the molecular properties of alpha-helices and alpha-form crystallites. Furthermore, the Flory-Huggins theory was employed to determine the water-helix interaction parameter (chi = 4.5) and the alpha-form crystallinity of human hair (22%), a figure consistent with that obtained by the XRD method (21%).
Cao
Jinan
J
Industrial Research Institute Swinburne (IRIS), Swinburne University of Technology, P.O. Box 218, Hawthorn, 533-545 Burwood Road, Hawthorn, Victoria, 3122 Australia.
Leroy
Frédéric
F
D000328:Adult; D002152:Calorimetry, Differential Scanning; D002675:Child, Preschool; D005260:Female; D006197:Hair / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D007633:Keratins / Q000737:chemistry*; D008297:Male; D011489:Protein Denaturation; D013816:Thermodynamics
D007633:Keratins