Abstract

FT-IR spectra of collagen films set in a vacuum chamber have been measured as a function of time for evacuation at 35 and 75 °C. From the difference in the spectra before and after evacuation, three distinct peaks were found at 3080, 3240, and 3480 cm ^-1. The latter two peaks have been assigned to two types of water molecules bound in the collagen films from comparison with frequencies of solid and liquid water. The intensity change of these peaks with the evacuation time, therefore, indicates progress of the desorption of water from the collagen film. The first peak, its frequency being too low to be assigned to water, may be assigned to some functional groups of collagen which bind tightly to the water molecules. This suggestion is supported by the fact that the rate of intensity change during evacuation is approximately the same for the 3080- and 3240-cm ^-1 peaks. On the other hand, the intensity of the 3480-cm ^-1 peak changes faster, which means that the water molecules assigned to this peak are more loosely bound in the collagen film than are those assigned to the 3240-cm ^-1 peak. It has been found that the rate coefficients of water desorption decrease with the evacuation time. This result is probably due to the effect of the diffusion of water through the collagen film.

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