Preparation of silk resins by hot pressing Bombyx mori and Eri silk powders

We investigate the mechanical properties and structure of silk resins as potential alternatives to tortoiseshell for producing eyeglass frames and various ornaments. Silk powders are obtained from Bombyx mori and Eri silk waste fibers before the degumming process. The powders are fabricated into resins via simple hot pressing under a pressure of 31.2 MPa at temperatures in the range 150-180 °C. The results indicate that the B. mori resins have higher micro-Vickers hardness, three-point bending strength, and elastic modulus (66 Hv, 122 MPa, and 8.7 GPa, respectively) compared to the Eri silk resins (58 Hv, 95 MPa, and 8.2 GPa, respectively). The better mechanical properties of the fibroin resins are related directly to longer drying times. The optimum drying conditions are found to be at a temperature of 100 °C under a-vacuum of -0.1 MPa for a time of 7 d. ATR-FTIR and XRD results show how the fibroin structure changes after resinification and drying. The morphology and the distribution size of particle of the silk powders and the fractured surfaces of the resins are analyzed from SEM micrographs. The present findings demonstrate that silk resins are suitable materials for developing useful applications because of their favorable mechanical properties.