Abstract
Thermal properties of drag lines collected from Nephila clavata, Yaginumia sia and Argiope amoena were studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) at temperatures from 20°C to 600°C. The DSC thermograms obtained for N. clavata showed an endothermic peak at ca. 100°C and exothermic peaks at ca. 300, 340, 500 and 580°C. The former could be ascribed to the desorption of water from the protein constituting drag lines and the latter to decomposition of the protein. Tce spider's silk thread was stable even above 200°C but completely decomposed at ca. 600°C. The thermal properties of drag lines were found to change with season and depended on the sex as well as species of the spider. Such difference in the thermal properties may be ascribed to the differences not only in the physical properties such as the morphology of silks, the molecular weight and density but also in the chemical structure such as the amino acid composition.
