Chemical modification of wood by non-formaldehyde cross-linking reagents

Yasuda, Rie; Minato, Kazuya

doi:10.1007/bf00202084

Cited by 12 publications

(6 citation statements)

References 7 publications

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“…A similar pattern, although more pronounced, is known from chemical wood modifications which are based on crosslinking, such as formalization. The enhanced cross-linking caused by formalization has been suggested to result in a stiffening of the cell wall matrix which restrains the expansion of the cell wall nanopores and thus reduces water sorption (Yasuda et al 1994;Himmel and Mai 2015), which is in line with the effect proposed for TM of oven-dry samples.…”

Section: Hygroscopicity Tested On Wood Particlesmentioning

confidence: 60%

Wood moisture content during the thermal modification process affects the improvement in hygroscopicity of Scots pine sapwood

2016

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Elevated wood moisture contents during the thermal modification process have been shown to adversely affect the improvement in dimensional stability and hygroscopicity. This study tested the hypothesis that the effect of elevated wood moisture content is based on the impact of water on chemical reactions which determine the cell wall matrix stiffness. Samples of Scots pine sapwood (Pinus sylvestris L.) were thermally modified in saturated water vapor at different peak temperatures and durations starting either in oven-dry or in water-saturated state. For a given mass loss caused by the modification process, the improvement in maximum swelling and equilibrium moisture content was stronger for oven-dry samples. After removal of water-soluble degradation products, which caused a cell wall bulking effect, the maximum swelling even increased after modification in water-saturated state. Based on dynamic vapor sorption measurements, it was evidenced that the modification in oven-dry state increased the cell wall matrix stiffness which improved dimensional stability and hygroscopicity. Enhanced bond formation in the polymeric network, i.e., via condensation and cross-linking reactions during the treatment of oven-dry wood, is suggested as a cause for this increase in matrix stiffness. In contrast, the modification in water-saturated state enhanced the flexibility of the cell wall matrix, which increased the cell wall swelling and limited the improvement of hygroscopicity to the reduction in OH groups by removal of hemicelluloses. This enhanced matrix flexibility was potentially caused by predominant hydrolytic cleavage of bonds in case of water-

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Section: Hygroscopicity Tested On Wood Particlesmentioning

confidence: 60%

Wood moisture content during the thermal modification process affects the improvement in hygroscopicity of Scots pine sapwood

2016

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“…Several liquid monomers such as styrene2, 12, 13 and methyl methacrylate14, 15 are also incorporated into wood samples by means of chemical impregnation. Crosslinking of wood with chemicals1, 2, 3, 6, 7, 16 provides good dimensional stability to the wood–polymer composite.…”

Section: Introductionmentioning

confidence: 99%

Treatment of Caribbean pine by in situ polymerization of styrene and furfuryl alcohol

Magalhães

Silva²

2003

J of Applied Polymer Sci

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Caribbean pine impregnated by the full cell treatment schedule with styrene, furfuryl alcohol (FFA), and styrene-FFA monomers was cured for 48 h at 100°C. Styrene did not penetrate inside the wood cell wall; instead, it adhered on the cell wall surfaces and fill cell lumens. The volume contraction during the formation of polystyrene causes the volume contraction of the wood sample. The permanent volumetric swelling is attained only for samples treated with FFA, which is caused by cell wall impregnation. The dimensional stability of the treated wood samples is evaluated with the antiswell efficiency coefficient (ASE). The water repellency is expressed as the water-repellent effectiveness (WRE). Treatment with styrene improves the water repellence, whereas a double treatment increases the dimensional stability. Lixiviation slightly affects the ASE and WRE coefficients. The treatments improve the Shore D hardness in comparison to untreated wood.

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“…The absorbance around 1,510 cm -1 was due to benzene ring stretching vibration in lignin (Harrington et al 1964;Michell et al 1965), which was stable for the treatment; thus, it could be used as benchmark. The absorption at 1,160 cm -1 was due to antisymmetric bridge stretching vibration (C-O-C) (Harrington et al 1964;Michell et al 1965;Nakano 1993;Yasuda and Minato 1995). In comparison with the untreated wood, the absorption ratio around 1,160 cm -1 , which is due to ester bond, nearly did not change in treated wood only with glyoxal; however, when glycol was added, the absorbance ratio of 1,160-1,510 cm -1 increased, indicating the formation of ether bond, which may result from the reaction between glyoxal and glycol or glyoxal with wood cell wall components.…”

Section: Ir Analysismentioning

confidence: 97%

“…Glycol, which has two alcoholic hydroxyl groups and can react with glyoxal, was added to reduce the yellowing effects and stabilize the bond between glyoxal and wood (Welch 1984;Yasuda and Minato 1995). Different amounts of glycol were added, and the results of its effects are presented in Fig.…”

Section: Glycol-to-glyoxal Molar Ratiomentioning

confidence: 99%

“…Treatment of wood with glyoxal using sulfur dioxide (SO 2 ) as a catalyst was reported and compared with formaldehyde treatment in terms of dimensional stability, acoustic properties and mechanical strength (Yasuda et al 1994a). The moisture adsorption and creep properties were further studied (Yasuda et al 1994b). Although a number of references on use of glyoxal in wood modification are available in the literature, only scarce work has been done about the effect of various parameters on properties of modified wood.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of reaction parameters and characterization of glyoxal-treated poplar sapwood

Yan

Dong

et al. 2014

Wood Sci Technol

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Glyoxal as a non-formaldehyde cross-linking agent was employed with ammonium persulfate as a novel catalyst to improve the dimensional stability and water resistance of poplar sapwood. The effects of various cross-linking parameters (e.g., glyoxal concentration, curing temperature, glycol-to-glyoxal molar ratio and catalyst concentration) on the properties of wood were investigated, and the parameters were optimized. In comparison with the unmodified wood, the glyoxalmodified wood exhibited improved dimensional stability and reduced water uptake. Moreover, the addition of glycol further strengthened the dimensional stability and anti-leaching ability. Modified wood was characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM) and contact angle instrument. IR indicated that the network structure was formed between the agent itself or cross-linking between wood components and glyoxal. SEM revealed the precipitation and filling effect of the cured glyoxal in the cell wall. Contact angle measurement further confirmed the improved hydrophobicity of wood after modification. All the results suggested that the improved dimensional stability and water resistance of the treated wood could attribute to both bulking effect and cross-linking reaction or network structure formed. However, it is not clear whether network structure by glyoxal itself or the cross-linking between the glyoxal and wood components is formed in wood.Y. Yan and Y. Dong have contributed equally to this work.

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Chemical modification of wood by non-formaldehyde cross-linking reagents

Cited by 12 publications

References 7 publications

Wood moisture content during the thermal modification process affects the improvement in hygroscopicity of Scots pine sapwood

Wood moisture content during the thermal modification process affects the improvement in hygroscopicity of Scots pine sapwood

Treatment of Caribbean pine by in situ polymerization of styrene and furfuryl alcohol

Optimization of reaction parameters and characterization of glyoxal-treated poplar sapwood

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