화학공학소재연구정보센터
Thermochimica Acta, Vol.615, 8-14, 2015
Using flash DSC for determining the liquid state heat capacity of silk fibroin
In this technical note, we report a study of the heat capacity of amorphous silk fibroin protein evaluated using the Flash DSC1 for fast scanning calorimetry. Nineteen amorphous thin films were obtained either after casting directly from water solutions, or after melting of previously crystalline films. Fibroin films were mounted onto Flash DSC1 sensors, dried free of bound water, relaxed just above the glass transition, T-g, then scanned in heating and cooling at 2000 K/s. The heat flow rate data were analyzed by finding the symmetry line between the heating and cooling scans, and by subtraction of the empty sensor heat flow rate, similarly corrected for its symmetry line. To evaluate the sample mass, two approaches were compared. First, the mass was obtained from known solid state heat capacity, C-p(solid)(T), at a temperature below Tg. Second, the mass was obtained from the known heat capacity increment at the glass transition, Delta C-p(T-g). The C-p(solid)(T) and Delta C-p(Tg) had been obtained previously from slow scanning differential scanning calorimetry. The use of either method for mass determination necessitated additional corrections to the heat capacity data to bring them into agreement with the literature values. After these corrections, the heat capacity of silk fibroin in the liquid state was evaluated over a wide temperature range above Tg. We find C-p(liquid)(T) = (1.98 +/- 0.06) J/g K+ T.(6.82 +/- 1.4) x 10(-4) J/g K-2 in the temperature interval from 510 to 570K with an uncertainty of about +/-5%. (C) 2015 Elsevier B.V. All rights reserved.