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The Structural Origins of Wood Cell Wall Toughness
Author(s) -
Maaß MonaChristin,
Saleh Salimeh,
Militz Holger,
Volkert Cynthia A.
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201907693
Subject(s) - materials science , toughness , microfibril , composite material , cellulose , fracture toughness , toughening , cell wall , stiffness , lignin , chemical engineering , biochemistry , chemistry , organic chemistry , engineering
The remarkable mechanical stability of wood is primarily attributed to the hierarchical fibrous arrangement of the polymeric components. While the mechanisms by which fibrous cell structure and cellulose microfibril arrangements lend stiffness and strength to wood have been intensively studied, the structural origins of the relatively high splitting fracture toughness remain unclear. This study relates cellulose microfibril arrangements to splitting fracture toughness in pine wood cell walls using in situ electron microscopy and reveals a previously unknown toughening mechanism: the specific arrangement of cellulose microfibrils in the cell wall deflects cracks from the S2 layer to the S1/S2 interface, and, once there, causes the crack to be repetitively arrested and shunted along the interface in a zig‐zag path. It is suggested that this natural adaptation of wood to achieve tough interfaces and then deflect and trap cracks at them can be generalized to provide design guidelines to improve toughness of high‐performance and renewable engineering materials.