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

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 693
Author(s):  
Elin Xiang ◽  
Rongfeng Huang ◽  
Shumin Yang
Keyword(s):  
Elastic Modulus ◽  
Creep Resistance ◽  
Cell Walls ◽  
Superheated Steam ◽  
Untreated Wood ◽  
Fiber Cell ◽  
Steam Treatment ◽  
Densified Wood ◽  
Relative Crystallinity ◽  
Fiber Cell Wall

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.

scholarly journals Determination of the Effects of Superheated Steam on Microstructure and Micromechanical Properties of Bamboo Cell Walls Using Quasi-Static Nanoindentation

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1742
Author(s):  
Tiancheng Yuan ◽  
Xiaorong Liu ◽  
Youming Dong ◽  
Xinzhou Wang ◽  
Yanjun Li
Keyword(s):  
Elastic Modulus ◽  
Cell Walls ◽  
Superheated Steam ◽  
Lignin Content ◽  
Crystallinity Index ◽  
X Ray Diffraction ◽  
Untreated Sample ◽  
X Ray ◽  
Micromechanical Properties

In this paper, quasi-static nanoindentation was applied for investigating the influence of superheated steam on microstructure and micromechanical properties of Moso bamboo cell walls. The changes of mico-morphology, chemical composition, cellulose crystallinity index, micro-mechanical properties of bamboo were analyzed via scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and nanoindentation. As expected, the content of hemicellulose and cellulose showed a downward trend, whereas the relative lignin content increased. Elastic modulus and hardness of the cell wall increased compared with that of the untreated sample. The elastic modulus and hardness of bamboo increased from 11.5 GPa to 19.5 GPa and from 0.35 GPa to 0.59 GPa. Furthermore, results showed that the creep resistance positively correlated to treatment severity.

scholarly journals Involvement of CesA4, CesA7-A/B and CesA8-A/B in secondary wall formation in Populus trichocarpa wood

2019 ◽  
Vol 40 (1) ◽  
pp. 73-89 ◽  
Author(s):  
Manzar Abbas ◽  
Ilona Peszlen ◽  
Rui Shi ◽  
Hoon Kim ◽  
Rui Katahira ◽  
...  
Keyword(s):  
Solid State ◽  
Mechanical Strength ◽  
Cell Walls ◽  
Secondary Wall ◽  
Populus Trichocarpa ◽  
Wood Formation ◽  
Fiber Cell ◽  
Modulus Of Rupture ◽  
Cellulose Content ◽  
Wall Formation

Abstract Cellulose synthase A genes (CesAs) are responsible for cellulose biosynthesis in plant cell walls. In this study, functions of secondary wall cellulose synthases PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B were characterized during wood formation in Populus trichocarpa (Torr. & Gray). CesA RNAi knockdown transgenic plants exhibited stunted growth, narrow leaves, early necrosis, reduced stature, collapsed vessels, thinner fiber cell walls and extended fiber lumen diameters. In the RNAi knockdown transgenics, stems exhibited reduced mechanical strength, with reduced modulus of rupture (MOR) and modulus of elasticity (MOE). The reduced mechanical strength may be due to thinner fiber cell walls. Vessels in the xylem of the transgenics were collapsed, indicating that water transport in xylem may be affected and thus causing early necrosis in leaves. A dramatic decrease in cellulose content was observed in the RNAi knockdown transgenics. Compared with wildtype, the cellulose content was significantly decreased in the PtrCesA4, PtrCesA7 and PtrCesA8 RNAi knockdown transgenics. As a result, lignin and xylem contents were proportionally increased. The wood composition changes were confirmed by solid-state NMR, two-dimensional solution-state NMR and sum-frequency-generation vibration (SFG) analyses. Both solid-state nuclear magnetic resonance (NMR) and SFG analyses demonstrated that knockdown of PtrCesAs did not affect cellulose crystallinity index. Our results provided the evidence for the involvement of PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B in secondary cell wall formation in wood and demonstrated the pleiotropic effects of their perturbations on wood formation.

Effects of superheated steam treatment on moisture adsorption and mechanical properties of pre-dried rubberwood

2018 ◽  
Vol 37 (13) ◽  
pp. 1647-1655
Author(s):  
Anatta Patcharawijit ◽  
Nuttaporn Choodum ◽  
Ram Yamsaengsung
Keyword(s):  
Mechanical Properties ◽  
Superheated Steam ◽  
Steam Treatment ◽  
Moisture Adsorption

The Improvement of Durability of Marine Wood with Polymer and its Mechanism

2009 ◽  
Vol 79-82 ◽  
pp. 1021-1024 ◽  
Author(s):  
Yong Feng Li ◽  
Yi Xing Liu ◽  
Xiang Ming Wang ◽  
Xiu Rong Li
Keyword(s):  
Porous Structure ◽  
Dimensional Stability ◽  
Cell Walls ◽  
Treated Wood ◽  
Untreated Wood ◽  
Decay Resistance ◽  
Hydroxyl Group ◽  
Alkali Resistance ◽  
Hydroxyl Groups ◽  
Marine Corrosion

In order to improve the durability of marine wood against the long-term marine corrosion, the study explores to use two bifunctional reagents, maleic anhydride (Man) and glycidyl methacrylate(GMA), to react with wood by impregnating them into the porous structure of wood and further initiating them to polymerize with an initiator, AIBN, through a heat process. After the above modification, the durability of the marine wood treated with polymer was tested, and its mechanism was further analyzed as well. The testing results of the durability show that the acid resistance, the alkali resistance, the decay resistance against marine borers and the dimensional stability of the treated wood increases by 2.02 times, 12.39 times, 4.96 times and 3 times over untreated wood, respectively; and its Anti Swelling Efficiency (ASE) for dimensional stability reaches 53%, which almost equals the value of the wood treated by PEG-1500 under the same condition, while its leachability resistance is greatly higher than wood treated by PEG-1500. The analysis result with FTIR indicates that Man and GMA both react with wood, and Man reacts with the hydroxyl group of wood cell walls by its anhydride group, and GMA polymerizes in the porous structure of wood. The charactering result with SEM reveals that the resultant polymer fills in wood cell lumina as a solid form, which contacts tightly the wood cell walls without obvious gaps. The greatly reducing amount of hydroxyl groups after the reaction and the heavy jamming channels for water and marine borers approaching to wood cell walls both contribute to the improving durability of the modified wood.

UV Absorption Microspectrophotometry and Histochemistry of Flax and Kenaf

1998 ◽  
Vol 4 (S2) ◽  
pp. 846-847
Author(s):  
D.E. Akin
Keyword(s):  
Microbial Degradation ◽  
Linum Usitatissimum ◽  
Cell Walls ◽  
Industrial Applications ◽  
Hibiscus Cannabinus ◽  
Fiber Cell ◽  
The Other ◽  
Uv Absorption ◽  
Bast Fibers ◽  
Histochemical Tests

Flax (Linum usitatissimum L.) and kenaf (Hibiscus cannabinus L.) are the sources of fibers used for textiles and other industrial applications. Both flax and kenaf produce fibers in the bast region (Fig. 1, 2) which must be separated from other tissues by retting. Although both flax and kenaf are bast fibers, their properties are vastly different. UV absorption microspectrophotometry and histochemistry elucidate their chemistry and structure related to enzymatic retting.Aromatics such as lignins are produced by plants for protection and strength, but their presence inhibits microbial degradation, which is necessary in retting. Histochemical tests indicated variations in the site and type of aromatics within these two plants (1,2). In flax, acid phloroglucinol but not chlorine-sulfite gave positive reactions occasionally in fiber cell walls in the bast. The other cell walls in the bast did not contain aromatics by these tests, although aromatics occurred in the cuticle.

scholarly journals Long-Term Creep Behavior Prediction of Sol-Gel Derived SiO2- and TiO2-Wood Composites Using the Stepped Isostress Method

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1215 ◽  
Author(s):  
Ke-Chang Hung ◽  
Tung-Lin Wu ◽  
Jyh-Horng Wu
Keyword(s):  
Creep Behavior ◽  
Creep Resistance ◽  
Flexural Modulus ◽  
Sol Gel ◽  
Untreated Wood ◽  
Behavior Prediction ◽  
Inorganic Composites ◽  
Sol Gel Process ◽  
Term Creep

In this study, methyltrimethoxysilane (MTMOS), methyltriethoxysilane (MTEOS), tetraethoxysilane (TEOS), and titanium(IV) isopropoxide (TTIP) were used as precursor sols to prepare wood-inorganic composites (WICs) by a sol-gel process, and subsequently, the long-term creep behavior of these composites was estimated by application of the stepped isostress method (SSM). The results revealed that the flexural modulus of wood and WICs were in the range of 9.8–10.5 GPa, and there were no significant differences among them. However, the flexural strength of the WICs (93–103 MPa) was stronger than that of wood (86 MPa). Additionally, based on the SSM processes, smooth master curves were obtained from different SSM testing parameters, and they fit well with the experimental data. These results demonstrated that the SSM was a useful approach to evaluate the long-term creep behavior of wood and WICs. According to the Eyring equation, the activation volume of the WICs prepared from MTMOS (0.825 nm3) and TEOS (0.657 nm3) was less than that of the untreated wood (0.832 nm3). Furthermore, the WICs exhibited better performance on the creep resistance than that of wood, except for the WICMTEOS. The reduction of time-dependent modulus for the WIC prepared from MTMOS was 26% at 50 years, which is the least among all WICs tested. These findings clearly indicate that treatment with suitable metal alkoxides could improve the creep resistance of wood.

Tensile properties of recycled carbon fibers subjected to superheated steam treatment under various conditions

2020 ◽  
Vol 133 ◽  
pp. 105869
Author(s):  
Guangbin Cai ◽  
Masashi Wada ◽  
Isamu Ohsawa ◽  
Satoshi Kitaoka ◽  
Jun Takahashi
Keyword(s):  
Tensile Properties ◽  
Carbon Fibers ◽  
Superheated Steam ◽  
Steam Treatment
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