Physical properties and structure of silk. V. Thermal behavior of silk fibroin in the random‐coil conformation

Abstract

Abstract The thermal behavior of films of amorphous silk fibroin in the random‐coil conformation has been investigated in the temperature range 25–220°C by differential scanning calorimetry (DSC), thermal expansion, dynamic mechanical measurements, x‐ray diffraction, and infrared spectroscopy. As the temperature is raised, water is lost up to about 100°C. Intramolecular and intermolecular hydrogen bonds are broken between 150 and 180°C. The glass transition is observed at 173°C by DSC. The random‐coil→β‐form transition accompanied by reformation of hydrogen bonds takes place above 180°C. Thermally induced crystallization to the β‐form crystals starts at about 190°C.