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© 1977 Society of Cosmetic Chemists
Journal of the Society of Cosmetic Chemists, Vol. 28, No. 11, 695-704


The tensile properties of hair fibers in 1-propanol water mixtures
D. Lu , M. M. Breuer

ABSTRACT

Synopsis

The stress-strain curves of intact hair fibers immersed in aqueous 1-propanol solutions were measured as functions of 1-propanol concentration, pH and temperature. Plots of the tensile forces at given extensions against the propanol concentrations show minima at about 50 per cent propanol; these become more pronounced at low pH values and at higher temperatures.

The experimental results can be interpreted by assuming that two additive molecular processes are responsible for the elasticity of hair: conformational changes of the polypeptide chains and electrostatic interactions between the various ionic side chains. The presence of 1-propanol in low concentrations accentuates the importance of the latter process by diminishing the value of the effective dielectric constant inside the hair structure. At high propanol concentrations, however, the dehydration of the fibers increases the relative contribution of the conformational changes and brings about a strengthening of the hair.

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© 1977 Society of Cosmetic Chemists
Journal of the Society of Cosmetic Chemists