Flat silk cocoons: A candidate material for fabricating lightweight and impact-resistant composites

Area of Science:

• Materials Science
• Composite Materials
• Biomaterials

Background:

• Normal silk cocoons (NSC) have limited applications in composites due to size and shape constraints.
• Flat silk cocoons (FSC) offer a solution with controllable size and similar structure.
• Developing advanced composites from natural materials is a key research area.

Purpose of the Study:

• To prepare and characterize flat silk cocoons (FSC).
• To fabricate and evaluate a novel silk fibroin fiber reinforced sericin matrix composite (HPFSC) using FSC.
• To assess the potential of FSC-based composites as lightweight, impact-resistant materials.

Main Methods:

• Systematic characterization of FSC and NSC (microstructure, morphology, composition, thermal, mechanical properties).
• Fabrication of HPFSC using a hot pressing method.
• Analysis of HPFSC: microstructure evolution, mechanical properties, failure modes, and theoretical modeling.

Main Results:

• FSC were successfully prepared and characterized, showing comparable properties to NSC but with controllable dimensions.
• HPFSC exhibited outstanding mechanical properties, including high hardness, modulus, and strength.
• HPFSC demonstrated a low density (~1.3 g/cm³) and exceptional impact energy absorption (up to 11.1 J/mm).

Conclusions:

• Flat silk cocoons (FSC) are a viable precursor for advanced composites.
• The novel HPFSC composite offers superior impact resistance and lightweight properties compared to many engineering materials.
• This research provides a pathway for utilizing FSC in lightweight, impact-resistant composite applications.