Changes in the cell wall volume of a number of wood species due to reaction with acetic anhydride

Kwon, Jin Kyung; Hill, Callum A. S.; Ormondroyd, Graham; Karim, Siti Fatma Abd

doi:10.1515/hf.2007.025

Cited by 19 publications

(10 citation statements)

References 6 publications

(10 reference statements)

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“…Acetylation therefore should not be capable of filling cavities significantly larger than the acetyl group themselves, but only form a layer on part of the walls of the cavity. The size of an acetyl group is influenced by its nearby environment (Kwon et al 2007). However, computer simulations of acetylated galactopyranose by Thibodeaux et al (2002) can give an idea of the size.…”

Section: Water In Modified Woodmentioning

confidence: 99%

Water sorption in wood and modified wood at high values of relative humidity. Part I: Results for untreated, acetylated, and furfurylated Norway spruce

Engelund²,

2010

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Desorption isotherms at 208C for untreated, acetylated, and furfurylated Norway spruce wPicea abies (L.) Karst.x sapwood were established in the 91.9-99.9% relative humidity (RH) range. Three methods were employed to secure various constant RH levels: saturated salt solutions, climate chambers, and the pressure plate technique. The curve form for the untreated samples did not show an upward bend, except perhaps above 99.5% RH, indicating that -contrary to what has hitherto been assumed -capillary condensation does not play a significant role for water sorption in wood below fiber saturation. Three additional results corroborate this conclusion: (1) calculation of the theoretical contribution of capillary condensation to the moisture content (MC) in wood based on idealized microstructural geometries by means of the Kelvin and Laplace equations resulted in very small contributions to the equilibrium moisture content (EMC), i.e., below 0.35% moisture at 99.9% RH. (2) The ratio between the EMC of acetylated and untreated samples did not show an increasing trend for increasing RH, as would have been the case if capillary condensation had taken place in both untreated and acetylated wood. (3) Low field time domain nuclear magnetic resonance results showed that only the relaxation curves from the furfurylated samples were affected systematically by freezing, indicating that neither untreated nor acetylated wood contained significant amounts of capillary condensed water.

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Section: Water In Modified Woodmentioning

confidence: 99%

Water sorption in wood and modified wood at high values of relative humidity. Part I: Results for untreated, acetylated, and furfurylated Norway spruce

Engelund²,

2010

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“…Mapping and visualization of these structural changes increase the understanding of the mechanism of chemical modification and facilitate the optimization of the modification parameters. Sander et al (2003), Kwon et al (2007) and Wålinder et al (2009) studied microstructural changes induced by chemical modification of wood. For instance, acetylation was observed by electron microscopy (EM), and no evidence was found for cell wall damages or significant change in the microstructure (Sander et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Microstructure of chemically modified wood using X-ray computed tomography in relation to wetting properties

et al. 2016

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X-ray computed tomography (XCT) was utilized to visualize and quantify the 2D and 3D microstructure of acetylated southern yellow pine (pine) and maple, as well as furfurylated pine samples. The total porosity and the porosity of different cell types, as well as cell wall thickness and maximum opening of tracheid lumens were evaluated. The wetting properties (swelling and capillary uptake) were related to these microstructural characteristics. The data show significant changes in the wood structure for furfurylated pine sapwood samples, including a change in tracheid shape and filling of tracheids by furan polymer. In contrast, no such changes were noted for the acetylated pine samples at the high resolution of 0.8 μm. The XCT images obtained for the furfurylated maple samples demonstrated that all ray cells and some vessel elements were filled with furan polymer while the fibers largely remained unchanged. Furfurylation significantly decreased the total porosity of both the maple and pine samples. Furthermore, this was observed in both earlywood (EW) and latewood (LW) regions in the pine samples. In contrast, the total porosity of pine samples was hardly affected by acetylation. These findings are in line with wetting results demonstrating that furfurylation reduces both swelling and capillary uptake in contrast to acetylation which reduces mostly swelling. Furfurylation significantly increased the cell wall thickness of both the maple and pine samples, especially at higher levels of furfurylation.

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“…However, wood, especially low-quality wood like poplar wood, may also have some undesirable properties, for example dimension changes (swelling and shrinking) under changing humid conditions (Hill 2008). Hydroxyl groups of the macromolecules within the cell wall are mainly responsible for water absorption and swelling (Obataya et al 2001;Kwon et al 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Thus a combined two-step treatment with multifunctional monomers should be developed. In the first step, maleic anhydride (MAN) was expected to penetrate and swell the cell wall matrix and to reduce the number of hydroxyl groups (Kwon et al 2007). In the second step, glycidyl methacrylate (GMA) as a coupling agent combined with methyl methacrylate (MMA) should then be applied to copolymerize in the cell lumens to further reduce hydroxyl groups.…”

Section: Introductionmentioning

confidence: 99%

Improvement of dimensional stability of wood via combination treatment: swelling with maleic anhydride and grafting with glycidyl methacrylate and methyl methacrylate

et al. 2012

Holzforschung

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A novel two-step combined treatment of poplar wood was developed to improve its dimensional stability. Maleic anhydride (MAN) was first employed to swell and bond to the wood cell wall, and then mixed monomers of glycidyl methacrylate/methyl methacrylate (GMA/MMA) were grafted to the cell wall through the chemical reaction with MAN within the wood cell lumen. The results of scanning electron microscopy and energy dispersive X-ray apparatus (SEM-EDX) and Fourier transform infrared spectroscopy (FTIR) analyses indicate that MAN penetrated and chemically bonded to the cell wall causing 9% volume swelling, and the copolymer from GMA/MMA monomers was grafted onto the wood cell wall, resulting in the improved interfacial compatibility between the polymer and wood matrix. The dimensional stability of poplar wood modified by the combined two-step treatment was remarkably improved compared with that of untreated poplar wood. The combination treatment of wood employed in this study proved to be more effective for improving the dimensional stability than treatment with PEG-1000 aqueous solution with 30% concentration.

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Changes in the cell wall volume of a number of wood species due to reaction with acetic anhydride

Cited by 19 publications

References 6 publications

Water sorption in wood and modified wood at high values of relative humidity. Part I: Results for untreated, acetylated, and furfurylated Norway spruce

Water sorption in wood and modified wood at high values of relative humidity. Part I: Results for untreated, acetylated, and furfurylated Norway spruce

Microstructure of chemically modified wood using X-ray computed tomography in relation to wetting properties

Improvement of dimensional stability of wood via combination treatment: swelling with maleic anhydride and grafting with glycidyl methacrylate and methyl methacrylate

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