THE HYDROTHERMAL CONTRACTION OF COLLAGEN FIBERS AS A METHOD OF ITS STRUCTURE INVESTIGATION
L. V. Kukhareva
Institute of Cytology RAS, St. Petersburg;
e-mail: kochka-0734@mail.ru
The hydrothermal contraction of collagen fibers, that is sharp decrease of the fiber length in the narrow temperature range during their heating in water, is a
typical example of phase transition which is analogous to melting. General thermodynamic consideration of the melting of oriented polymer fibers was carried out
by Gee (1947) and Flory (1956). Flory derived and equilibrium dependence of force on temperature considering the melted polymer as an ideal rubber. We proposed
an experimental method for quantitative investigation of this process including estimation of two critical parameters, which are the critical tension and the critical
temperature. The necessary condition for the critical parameters estimation is the prior cross-linking of the fiber. We studied theoretically and by experiment the
influence of different factors on these critical parameters. We demonstrated the critical tension of hydrothermal collagen contraction to be an important characteristic
making possible the estimation of native collagen structure retaining and molecular orientation's degree. The critical tension value was used do advantage for the
collagen structure characteristic in some mammoth fossils skin, in bovine skin in the process of leather manufacture and in artificial collagen fibers. The initial
temperature of hydrothermal collagen contraction, what is known as shrinkage temperature using widely for the collagen tannage estimation, was shown to be
dependent on the occurrence of non-collagenous sheath on native collagen fibers.
Key words: collagen fibers, rat tail tendons, hydrothermal contraction, stress-temperature dependence, equilibrium melting, critical
parameters and critical tension
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