Explanation of Longitudinal Shrinkage of Wood Based on Interconnected Chain-Molecule Concept of Cell-Wall Structure

Cockrell, Robert A.

doi:10.1115/1.4017598

Cited by 5 publications

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“…Several explanations have been put forward as to the causes of nonlinearity in the longitudinal shrinking process. [7][8][9][10] For example, Sadoh and Kingston 10 concluded that nonlinearity is due to decreased slipping of the chain molecules against one another, and that this decrease is caused, in turn, by increasing interchain molecular bonding with reduced moisture content. On the other hand, according to Meylan, 7 it was assumed that the only cause of nonlinearity is a change in the elastic constants as the moisture content changes.…”

Section: Introductionmentioning

confidence: 99%

Behavior of the cellulose microfibril in shrinking woods

Abe

Yamamoto

2006

J Wood Sci

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We measured the longitudinal and tangential shrinking processes in wood specimens from Chamaecyparis obtuse Endl. with different microfibril angles (MFAs). The shape of the shrinking curve was compared with the MFA. Only the longitudinal shrinking process of specimens with a small MFA clearly showed nonlinearity, and the degree of nonlinearity increased as the MFA decreased. In contrast, the tangential shrinking process and the longitudinal shrinking process of compressio n wood with a large MFA were linear. The nonlinearity is probably caused by the longitudinal shrinkage of the noncrystalline region of the cellulose microfibril (CMF) in regions of low moisture content during water desorption. When the moisture content is high, the matrix substance in the cell wall begins to dry; however, the shrinkage in the chain direction is restrained by the rigid CMF. As the wood dries further, the noncrystalline region of the CMF embedded in the matrix substance begins to shrink. Because the longitudinal mechanical behavior of wood with a small MFA is greatly affected by a rigid CMF, longitudinal shrinkage increases suddenly at about 10% moisture content; as a result, the shrinking process shows nonlinearity.

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