Impact of hydration on the mechanical properties and damage mechanisms of natural silk fibre reinforced composites

• Published in: Composites. Part A, Applied science and manufacturing Applied science and manufacturing, 2021-08, Vol.147, p.106458, Article 106458
• Main Authors: Tian, Wenhan, Yang, Kang, Wu, Sujun, Yang, Jiping, Luo, Hongyun, Guan, Juan, Ritchie, Robert O.
• Format: Article
• Language: English
• Subjects: Acoustic emission; Dynamic mechanical thermal analysis; Interface; Natural fibers
• ISSN: 1359-835X; 1878-5840
• DOI: 10.1016/j.compositesa.2021.106458

•Silk-epoxy resin composites softened but maintained a tensile modulus of >1.5 GPa and almost invariable breaking energy after hydration treatment for 10 days.•Residual shear stresses may be created at the interface of SFRPs after hydration due to the water-induced glass transition in silk fibres.•Interfacial damage was the earliest and the dominant damage mode upon loading of hydrated SFRPs. Silk fibres exhibit good biodegradability, biocompatibility and balanced strength and toughness, which are useful for toughness/impact-critical composites in the biomedical field. However, the impact of hydration has not been studied for silk fibre-reinforced polymers (SFRPs). In this work, SFRPs fabricated vacuum-assisted resin infusion (VARI) were treated under three hydration conditions. A hydration condition of 40 °C at 89% relative humidity (RH) was sufficient to induce a reduction in the tensile and flexural modulus and yield strength of SFRPs. Acoustic emission (AE) analysis showed that interface failure played a key role in the damage modes of SFRPs. Although mild hydration treatment appeared not to affect SFRPs, high hydration led to more susceptible interfacial failure. This work is intended to reveal the structural mechanisms of SRPPs under hydration, and to provide a useful reference for potential biomedical applications.