Thermal bonded cocoon laminates via simple hot-press treatment

The thin silkworm cocoon is potential for producing lightweight and tough engineering applications. In this paper, cocoon laminates were prepared by a simple hot pressing method, which are thermally bonded by its own sericin. After being hot pressed at 130 degrees C for 30 s, cocoon pieces get tightly compressed with a high fiber volume fraction of 64.4%, leading to tensile strength of the cocoon pieces enhancing from 32 to 111 MPa. Besides, mechanical properties of the cocoon laminate are improved for strong sericin bonding between cocoon pieces by increasing hot pressing time from 30 to 90 s. The resulting cocoon laminate exhibits the maximum stress of 70 MPa at 11.3% strain. The failure ascribes to the debonding rather than the fracture of cocoon overlaps. Importantly, the tensile toughness is better than that of the high-volume-fraction silk fabric-reinforced epoxy composite. Our study may show a bright prospect in developing lightweight and tough cocoon laminates for natural precursor materials.