Sandwich compression of wood: effect of superheated steam treatment on sandwich compression fixation and its mechanisms

Xiang, Elin; Feng, Shanghuan; Yang, Shumin; Huang, Rongfeng

doi:10.1007/s00226-020-01237-7

Cited by 16 publications

(19 citation statements)

References 33 publications

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“…The decreases in SR for A2N p and A6 p were much more significant, which decreased to 31.7% from 7.5%, and 29.8% from 3.8%, respectively ( Figure 4 C). Similarly, Xiang et al [ 18 ] showed that the superheated steam contributed to reducing the SR from 47.1% to 23.9% for surface densified wood. Additionally, M50 p had a shrinkage rate of 7.3%, which could be attributed to the dissolution of hemicelluloses by the hydrolysis of the remaining acid under high temperatures.…”

Section: Resultsmentioning

confidence: 93%

“…Heat treatment has been employed at various temperatures (160–220 °C) and media reactions, such as vacuum, nitrogen, steam, and oil [ 17 ]. High temperature hydrothermally treated wood exhibits enhanced anti-weathering resistance and improved dimensional stability due to the release of the wood’s internal stresses [ 16 ] by means of micro-cracks in the cell wall, the degradation of hemicelluloses, the loss of C=O linkages to the aromatic skeleton in lignin, and the increase in crystallinity [ 18 ]. However, it is unclear if this set recovery is approximately more or less pronounced for the densified wood through delignification occurring with hemicellulose dissolution.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Microstructure, Chemical, and Physical Properties of Delignified and Densified Poplar Wood

Wang

Liu

et al. 2021

Materials

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Wood is an attractive and inherently sustainable alternative to many conventional materials. Recent research on improving wood mechanical strength emphasizes wood densification through the partial removal of lignin and hemicelluloses, therefore the chemical and physical properties of delignified and densified wood require further investigation. In this study, poplar wood samples were subjected to alkali and maleic acid hydrotropic delignification with varying degrees of lignin and hemicellulose removal followed by hot pressing, and the microstructure, chemical properties, and dimensional stability of densified wood through delignification were evaluated. The results showed that the complete wood cell collapse was observed near the surface of all the delignified wood blocks, as well as some micro-cracks in the cell walls. The chemical analysis indicated that delignification occurred mainly near the surface of the wood blocks and enhanced hydrogen bonding among the aligned cellulose fibers. For dimensional stability, the set recovery decreased with the increase in alkali dosage, and the considerable fixation of compressive deformation was obtained by a post-densification hydrothermal treatment at 180 °C. These results have demonstrated that the densified wood with delignification can be easily fabricated using the proposed method, and the densified wood exhibited great potential to be used as a sustainable material.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Characterization of Microstructure, Chemical, and Physical Properties of Delignified and Densified Poplar Wood

Wang

Liu

et al. 2021

Materials

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“…The peak at 1426 cm −1 is assigned to the CH 2 bending deformation in cellulose. According to previous reports, this absorption band is assumed to be essentially unaltered by the heat treatment [40,41]. Thus, the peak intensity at 1426 cm −1 is set as 1 and used for spectrum normalization.…”

Section: Effect Of Oil Heat Treatment On Chemical Functional Groups Of Bamboomentioning

confidence: 99%

The effect of oil heat treatment on biological, mechanical and physical properties of bamboo

Hao

Wang

Wang³

et al. 2021

J Wood Sci

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Bamboo is now widely used in construction, papermaking, textile, furniture and other fields because of its renewable, fast-growing, high-strength, high-yield and easy processing. However, compared with wood, bamboo and bamboo products are more vulnerable to damage by fungi and pests. An effective and eco-friendly method is urgently needed to improve their physical and chemical properties, decay resistance and anti-mildew properties, and hydrophobic properties. Here, bamboo was heated with methyl silicone oil. The effect of different temperatures (140 °C–200 °C) and different times (2 h–6 h) on the properties of bamboo was studied systematically, including chemical composition, physical and mechanical properties, surface wettability, decay resistance and anti-mildew property. No starch granules were observed inside the parenchymal cell lumen of bamboo specimen heat treated at 200 °C for 6 h. And with the increase of heat treatment temperature and time, the content of cellulose and hemicellulose decreases gradually while relative content of lignin increases due to its better thermal stability. Accordingly, the surface wettability decreases due to the changes of the surface functional groups and micro-morphologies. Under the condition of oil heat treatment at 160 °C for 2 h, the compressive strength parallel to grain of bamboo samples reach the maximum of 109.52 MPa. With further increase of heating temperature, the corresponding compressive strength decreases. The resulted bending strength and MOE both display similar changing trend. However, the optimal parameter is at 180 °C for 2 h, with the highest bending strength and MOE values of 142.42 MPa and 12,373.00 MPa, respectively. Finally, the decay resistance and anti-mildew property are dramatically enhanced with increased heat treatment temperature and time. All the corresponding changing mechanisms are investigated in depth and in detail. Our results provide comprehensive process parameters and micro-mechanism for the performance of oil heat treatment of bamboo, which can be used to guide the actual production.

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“…However, densified wood without any post-treatment has poor dimensional stability and returns to its initial raw shape and size when exposed to liquid water or even high humidity environments [4,7,8]. Some attempts have been made to overcome this issue, including synthetic resin impregnation [9,10], cross-linking reaction [11,12], heat treatment [13,14], saturated steam treatment [15,16], and superheated steam treatment [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

“…Among the various modification methods, superheated steam treatment has distinct superiority in the aspects of simple operation, low pressure-resistant requirements for equipment, cost-effectiveness, and lack of chemical additives. The compressive deformation of surface densified wood can be effectively stabilized under specific combinations of superheated steam treatment process parameters, even upon repeated exposure to moisture [17,18]. Surfaced densified wood treated with superheated steam can be used for non-structural applications, such as tabletops, solid wood flooring, and furniture, due to its excellent performance in surface hardness and dimensional stability [17].…”

Section: Introductionmentioning

confidence: 99%

Change in Micromechanical Behavior of Surface Densified Wood Cell Walls in Response to Superheated Steam Treatment

Xiang

Huang

Yang

2021

Forests

Self Cite

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The combination of surface densification and superheated steam treatment is an effective method to improve the mechanical properties and dimensional stability of low-density wood. The objective of the current work is to evaluate the effects of superheated steam treatment on the micromechanical behavior of surface densified wood. The microstructure, chemical composition, cellulose crystalline structure, and micromechanical behavior of surface densified wood under different superheated steam pressures were investigated. Results indicated that both 0.1 MPa and 0.3 MPa superheated steam treatments increased the elastic modulus and hardness of fiber cell walls in surface densified wood. However, the average creep ratio and maximum creep compliance J(50) of surface densified wood under 0.3 MPa decreased by 41.59% and 6.76%, respectively, compared with untreated wood. The improvement of elastic modulus, hardness and creep resistance of surface densified wood treated with superheated steam was associated with the increase of relative crystallinity (CrI) and crystalline size. In addition, 0.3 MPa superheated steam treatment displayed a better effect on the enhancement of the elastic modulus, hardness, and creep resistance of the fiber cell wall than 0.1 MPa superheated steam treatment.

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Sandwich compression of wood: effect of superheated steam treatment on sandwich compression fixation and its mechanisms

Cited by 16 publications

References 33 publications

Characterization of Microstructure, Chemical, and Physical Properties of Delignified and Densified Poplar Wood

Characterization of Microstructure, Chemical, and Physical Properties of Delignified and Densified Poplar Wood

The effect of oil heat treatment on biological, mechanical and physical properties of bamboo

Change in Micromechanical Behavior of Surface Densified Wood Cell Walls in Response to Superheated Steam Treatment

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