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Depression of the melting temperature by moisture for α‐form crystallites in human hair keratin
Author(s) -
Cao Jinan,
Leroy Frédéric
Publication year - 2005
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.20186
Subject(s) - crystallite , crystallinity , moisture , melting temperature , chemistry , water content , melting point depression , chemical engineering , materials science , crystallography , composite material , organic chemistry , geology , engineering , geotechnical engineering
DSC thermal analysis has been carried out for human hair samples with various moisture contents to investigate the melting temperature depression behavior of α‐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 α‐form crystallites in human hair varies with moisture content from 205°C for dry hair to 155°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 α‐helices and α‐form crystallites. Furthermore, the Flory–Huggins theory was employed to determine the water–helix interaction parameter (χ = 4.5) and the α‐form crystallinity of human hair (22%), a figure consistent with that obtained by the XRD method (21%). © 2004 Wiley Periodicals, Inc. Biopolymers, 2005