| Abstract: | Differential scanning calorimetry (DSC) and thermally stimulated current (TSC) were used to characterize human‐bone collagen. DSC glass‐transition and denaturation temperatures of the collagen in a dehydrated state were 90 and 215 °C, respectively. By TSC, the main relaxation mode, labeled α and located around 90 °C, could be attributed to the dielectric manifestation of the glass transition. The corresponding molecular movements are cooperative with a compensation temperature close to the denaturation temperature. At low temperatures and in a hydrated state, a second mode labeled β2 was observed at ?110 °C. Dehydration shifted this mode to higher temperatures, revealing a weak mode labeled γ at ?150 °C. This γ mode was attributed to motions of aliphatic side chains. An analysis of low‐temperature elementary spectra allowed us to assign the β2 mode to structural water movements and revealed an additional compensation phenomenon in the temperature range (?80 to ?50 °C). Because the compensation temperature of this mode was close to the collagen glass‐transition temperature, the corresponding mode β1 was attributed to polar side‐chain motions, precursors of a collagen glass transition. Finally, around ambient temperature, three sharp peaks were attributed to hydrogen bonds breaking. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 987–992, 2000 |
