The Effects of Lignin and Hemicellulose on Thermal-Softening Properties of Water-Swollen Wood

Furuta, Yuzo; Nakajima, Masamitsu; Nakanii, Eri; Ohkoshi, Makoto

doi:10.2488/jwrs.56.132

Cited by 41 publications

(30 citation statements)

References 11 publications

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“…Lignin is known to be responsible for the main thermal-softening transition in watersaturated wood, which has notably been studied by DMA (dynamic mechanical analysis) (Salmén 1984;Furuta et al 1997Furuta et al , 2000Furuta et al , 2008Furuta et al , 2010. Dynamic IR spectroscopy (in dry conditions) also indicates that lignin exhibits a much more viscoelastic behaviour than carbohydrates do (Akerholm and Salmén 2003).…”

Section: Role Of Variations In Matrix Chemistry On Viscoelastic Propementioning

confidence: 99%

Changes in viscoelastic vibrational properties between compression and normal wood: roles of microfibril angle and of lignin

Brémaud¹,

Ruelle

Thibaut³

et al. 2012

Holzforschung

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This study aims at better understanding the respective influences of specific gravity (1), microfibril angle (MFA), and cell-wall matrix polymers on viscoelastic vibrational properties of wood in axial direction. The wide variations of properties between normal wood (NW) and compression wood (CW) are in focus. Three young bent trees (Picea abies, Pinus sylvestris and Pinus pinaster) that recovered verticality were sampled. Several observed differences between NW and CW were highly significant in terms of anatomical, physical (1, shrinkage, CIELab colorimetry), mechanical (compressive strength), and vibrational properties. Specific dynamic modulus of elasticity (E'/1) decreases with increasing MFA, and Young's modulus (E') can be satisfactorily explained by 1 and MFA. Apparently, the type of the cell wall polymer matrix is not influential in this regard. The damping coefficient (tan2) does not depend solely on MFA of NW and CW. The tan2 -E'/1 relationship evidences that, at equivalent E'/1, the tan2 of CW is approx. 34% lower than that of NW. This observation is ascribed to the more condensed nature of CW lignins, and this is discussed in the context of previous findings in other hygrothermal and time/frequency domains. It is proposed that the lignin structure and the amount and type of extractives, which are both different in various species, are partly responsible for taxonomy-related damping characteristics.

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Section: Role Of Variations In Matrix Chemistry On Viscoelastic Propementioning

confidence: 99%

Changes in viscoelastic vibrational properties between compression and normal wood: roles of microfibril angle and of lignin

Brémaud¹,

Ruelle

Thibaut³

et al. 2012

Holzforschung

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show abstract

“…[10] It was reported that the thermal-softening property of the water-swollen wood was more greatly affected by changes in quantity and quality of lignin than by that of hemicellulose. [14] However, the effect of hemicellulose softening was rather important during the water-loss process due to the decrease of MC. [9] The softening of hemicellulose and/or lignin occurred at higher temperatures or higher MCs with shorter heating times.…”

Section: Introductionmentioning

confidence: 99%

The Viscoelastic Properties of Chinese Fir During Water-Loss Process Under Hydrothermal Conditions

Zhan

Jiang

2015

Drying Technology

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In this paper, the viscoelastic properties of water-swollen Chinese fir during water-loss process under different hydrothermal conditions (30 -90 °C, 40 -80 % RH) were investigated. After the 300min hydrothermal process at 70 or 90 °C, the moisture contents (MCs) of the specimens were well below the MC value at the fiber saturation point (FSP).During the hydrothermal process, normalized E′ increased at first, and then leveled off at temperatures above 50°C. The wood specimens were softened due to the hydrothermal effect. The glass transition of hemicellulose appeared at 50 °C. The lignin transition was observed at 70 and 90 °C. Superposition of transitions of lignin and hemicellulose moved to low storage modulus E′ with the increasing temperature and RH level. † These authors contributed equally to this work

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“…However, wood cannot be compressed at large amplitudes without an effective softening process. Hydrothermal treatment is considered to be one of the most effective softening methods for wood modification (Furuta et al 2010;Hamdan et al 2000;Kutnar et al 2009;Tjeerdsma and Militz 2005). Alkaline modification also reportedly induces swelling in the noncrystalline regions and deformation between microfibers.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Analysis on the Longitudinal Compression Characteristics of Juvenile and Mature Northeast Chinese Ash (Fraxinus mandshurica Rupr.) Subjected to Alkaline Treatment

Zhang

Song

2013

BioResources

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Longitudinal compression can help wood form some folds on the wood cell walls after a suitable softening procedure. These folds can enhance the one-and multi-dimensional bending performances of wood. The longitudinal compression properties of alkali-treated juvenile and mature northeast Chinese ash (Fraxinus mandshurica Rupr.) were analyzed. Elastic and elastic-plastic stages were inferred from the longitudinal compression curves. Scanning electron microscopy images showed that some folds formed in the wood cell wall vessels and fibers. X-ray microdensitometer test results showed a decrease in the fluctuation of the wood cell wall density of the specimens. The swelling and degradation or extraction of hemicellulose, lignin, and extractive occurred after alkaline treatment. Slippage between cellulose chains and curving within a cellulose chain were inferred during longitudinal compression. Juvenile wood specimens had higher modulus of elasticity and larger variability than mature wood after alkaline treatment. This finding can be attributed to the higher extent of degradation or extraction of hemicelluloses, lignin, and extractive, as well as the smaller microfibril angle and the similar cellulose crystallinity of treated juvenile wood compared to those of mature wood specimens after alkaline treatment.

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The Effects of Lignin and Hemicellulose on Thermal-Softening Properties of Water-Swollen Wood

Cited by 41 publications

References 11 publications

Changes in viscoelastic vibrational properties between compression and normal wood: roles of microfibril angle and of lignin

Changes in viscoelastic vibrational properties between compression and normal wood: roles of microfibril angle and of lignin

The Viscoelastic Properties of Chinese Fir During Water-Loss Process Under Hydrothermal Conditions

A Comparative Analysis on the Longitudinal Compression Characteristics of Juvenile and Mature Northeast Chinese Ash (Fraxinus mandshurica Rupr.) Subjected to Alkaline Treatment

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