Thermal behavior of regenerated Antheraea pernyi silk fibroin film treated with aqueous methanol

Abstract

The regenerated Antheraea pernyi silk fibroin films prepared from calcium nitrate solution were treated with 80% aqueous methanol. The thermal and dynamic thermomechanical behaviors of the films were investigated through TGA, DSC and DMTA. IR spectroscopy was used for the conformational changes with methanol treatments. The treatment time of aqueous methanol highly influenced the thermal behavior of regenerated films. As the methanol treatment time increased up to 60min, the thermal decomposition behavior did not differ significantly compared with untreated films while the endo/exo transition was gradually decreased, with the exotherm finally disappearing. The dynamic mechanical thermal behavior was also affected by the treatment time of aqueous methanol. The onset temperature of storage modulus drop or damping peak shifted to a higher temperature due to the increase in crystallinity induced by the methanol treatment. The thermal transition was strongly dependent on the formation of β-sheet crystal conformation of the regenerated films upon methanol treatment.