Crystallization of silk fibroin from solution

X-ray diffraction and differential scanning calorimetry (DSC) were carried out to clarify the crystallization mechanism of silk fibroin from liquid si lk (native silk fibroin solution), In the course of the evaporation of wate r from liquid silk, silk fibroin crystallizes when weight loss of water rea ches 40% at the temperatures below 120 degrees C, The crystallization occur s 20 min after the specimens are put at above 100 degrees C and 1-3 h at be low 100 degrees C, . In the DSC curve of liquid silk of domestic silk Bombyx mori, the alpha-bet a transition occurs at 51 degrees C. The crystallization temperatures of wi ld silk Antheraea yamamai, Antheraea pernyi and Dictyoploa japonica are 59, 67 and 62.5 degrees C, respectively. The exothermic DSC peaks at these tem peratures are attributed to the conformational change to the beta-form. (C) 2000 Elsevier Science B.V. All rights reserved.