Mode III Tear Resistance of Bombyx mori Silk Cocoons

Content Provider	Europe PMC
Author	Rehman, AteeqUr Koutsos, Vasileios Alam, Parvez
Copyright Year	2024
Description	This paper concerns the tear properties and behavior of Bombyx mori (B. Mori) silk cocoons. The tear resistance of cocoon layers is found to increase progressively from the innermost layer to the outermost layer. Importantly, the increase in tear strength correlates with increased porosity, which itself affects fiber mobility. We propose a microstructural mechanism for tear failure, which begins with fiber stretching and sliding, leading to fiber piling, and eventuating in fiber fracture. The direction of fracture is then deemed to be a function of the orientation of piled fibers, which is influenced by the presence of junctions where fibers cross at different angles and which may then act as nucleating sites for fiber piling. The interfaces between cocoon wall layers in B. mori cocoon walls account for 38% of the total wall tear strength. When comparing the tear energies and densities of B. mori cocoon walls against other materials, we find that the B. mori cocoon walls exhibit a balanced trade-off between tear resistance and lightweightness.
Abstract	This paper concernsthe tear properties and behaviorof Bombyx mori (B. Mori) silk cocoons. The tear resistance of cocoon layers is found toincrease progressively from the innermost layer to the outermost layer.Importantly, the increase in tear strength correlates with increasedporosity, which itself affects fiber mobility. We propose a microstructuralmechanism for tear failure, which begins with fiber stretching andsliding, leading to fiber piling, and eventuating in fiber fracture.The direction of fracture is then deemed to be a function of the orientationof piled fibers, which is influenced by the presence of junctionswhere fibers cross at different angles and which may then act as nucleatingsites for fiber piling. The interfaces between cocoon wall layersin B. mori cocoon walls account for38% of the total wall tear strength. When comparing the tear energiesand densities of B. mori cocoon wallsagainst other materials, we find that the B. mori cocoon walls exhibit a balanced trade-off between tear resistanceand lightweightness.
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Volume Number	4
DOI	10.1021/acsmaterialsau.4c00001
PubMed Central reference number	PMC11240411
Issue Number	4
PubMed reference number	PMC11240411
Journal	ACS Materials Au [ACS Mater Au]
e-ISSN	26942461
Language	English
Publisher	American Chemical Society
Publisher Date	2024-03-28
Access Restriction	Open
Rights License	Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/). © 2024 The Authors. Published by American Chemical Society
Subject Keyword	Bombyx mori silk cocoon tear resistance tear strength mode III failure textiles cocoon damage
Content Type	Text
Resource Type	Article
Subject	Materials Chemistry Biomaterials Polymers and Plastics Electronic, Optical and Magnetic Materials