Abstract
•We detail how microscale growth layers between nacre resist tension and shear.•We experimentally test the behavior of microscale growth layers using large samples.•Spherulites within growth layers are weak in shear.•Interfaces between spherulites and green matrices are weak in tension.
The microscale growth layers between nacre possess distinctive aragonite structures, including columns, spherulites and organic matrices. High temporal resolution experiments were performed to elucidate the tensile and shear behavior of growth layers under dry and hydrated conditions. For a comparison, pure nacre was tested in corresponding conditions. For both nacre and growth layers, the presence of water enabled larger deformation of hydrated specimens than those of dry specimens. Hydrated growth layers exhibited lower strengths and larger failure strains than hydrated nacre under both shear and tensile loadings. Hydrated growth layers exhibited lower work-to-failure than hydrated nacre under shear, whereas they exhibited higher work-to-failure than hydrated nacre under tension. This work could further our understandings on the interfacial behavior of laminated natural materials, and may help the creation of high performance hierarchical composites.
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