The contribution of water to the specific heat change at the glass-to-rubber transition of the ternary system BSA-water-NaCl

Inoue, C.; Ishikawa, M.

The contribution of water to the specific heat change at the glass-to-rubber transition of the ternary system BSA-water-NaCl

2000

Inoue, C. | Ishikawa, M.

We studied the glass-to-rubber transition of a BSA-water-NaCl system using DSC. The T(g) was 178-187 K and decreased with increasing NaCl content from 1:9 to 6:4 NaCl:BSA. The specific heat change (deltaC(p)*, J/((g BSA)K)) at T(g) increased as the weight ratio increased from 1:9 to 5:5 NaCl:BSA, as did the change in calculated unfrozen water (UFW). The UFW was also correlated with the amount of NaCl in the glassy region with a correlation coefficient of approx. 6 (mol H2O)/(mol NaCl), which is comparable to the hydration number of Na(+). These results suggest that UFW could contribute to the deltaC(p) at T(g) of the BSA-water system.

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