The Heat of the Phase Transformation in Wool Keratin Under Various Conditions

Abstract

Measurements were made of the heat of the phase transformation in wool. The measured heat varies with variation in the amount of water sealed with the sample and with variation in the heating rate. For instance, an increase in heating rate by a factor of four (approx. 0.5°C/min to 2°C/min) caused an increase in the measured heat of transformation from 3.9 cal/g to 7.3 cal/g. Parallel x-ray diffraction studies indicated that a lower rate of heating favored a crystal-crystal change (an α → β trans formation), and a higher rate favored a crystalline → noncrystalline change. In agree ment with others, our calculations indicate that the fraction of crystalline material in wool is approximately 0.25-0.30.