Wood mechanical properties and their correlation with microstructure in Chinese fir clones

IAWA Journal ◽  
2021 ◽  
pp. 1-10
Author(s):  
Yurong Wang ◽  
Ru Jia ◽  
Haiyan Sun ◽  
Yamei Liu ◽  
Jianxiong Lyu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Linear Regression Analysis ◽  
Microfibril Angle ◽  
Chinese Fir ◽  
Modulus Of Rupture ◽  
X Ray Diffraction ◽  
Average Cell ◽  
X Ray ◽  
Two Factors

Abstract Mechanical testing, microscopic image analysis, and X-ray diffraction were used to study the mechanical properties and their correlation with microstructure in three 20-year-old Chinese fir clones (Kailin 24, Kaihua 13, and Kaihua 3). The Chinese fir clones featured a modulus of rupture (MOR) of 52–59 MPa, a modulus of elasticity (MOE) of 10–11 GPa, and a compressive strength parallel to the grain of 31–34 MPa. Kaihua 13 and Kailin 24 had similar mechanical properties and were superior to Kaihua 3 among the tree clones. Radial variation indicated that their outerwood (rings 9–18) had better mechanical properties than their corewood (rings 3–7). Kaihua 13 with better mechanical properties had a larger ratio of cell wall to lumen than Kaihua 3 and Kailin 24. Outerwood with better mechanical properties also had a larger ratio of cell wall to lumen and a smaller microfibril angle compared to corewood with poor mechanical properties. Linear regression analysis also shows that for various clones and different radial positions in the same clone, anatomical structure parameters such as average cell wall thickness and the ratio of cell wall to lumen were positively correlated to their mechanical properties, while the microfibril angle was negatively correlated to mechanical properties. The two factors synergistically influence the mechanical properties of wood.

scholarly journals Water in Pinus Radiata Wood Secondary Cell Walls: An Investigation Using Nuclear Magnetic Resonance and Synchrotron X-Ray Diffraction

2021 ◽  
Author(s):  
◽  
Stefan James Hill
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Wood Cell Wall ◽  
Chemical Components ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
Green State ◽  
Nmr Study ◽  
Cellulose Crystals

<p>The mechanical properties of wood allow it to be used for numerous purposes. For most purposes, drying of the wood material from the green state, sawn from the log, is first required. This drying step significantly improves the strength properties of wood. It is therefore clear that moisture in wood plays an important role in determining the bulk mechanical properties. Over the last century, many studies have been carried out to investigate the way in which the water content wood affects the bulk mechanical properties. More recent studies have focused to the individual chemical components that make up wood to understand the observed changes in bulk mechanical properties. Models of the nanostructure of wood contained; cellulose, hemicellulose, and lignin, and the arrangement and location of these components in terms of their mechanical properties was interpreted through what was described as the 'slip-stick' mechanism, by which wood, in its green state, maintained its molecular and mechanical properties under external stresses. This model, while insightful, failed to account for the presence and the role of water in the nanostructure of wood. In this work, synchrotron based X-ray diffraction and NMR studies, have been used to develop a new model, in which water plays a vital role in the determination of the mechanical properties of wood in its green, part-dried, and rewet states. X-ray diffraction showed that changes occur to the molecular packing of cellulose crystallites with change in moisture content, and that these changes begin to occur under mild drying conditions, i.e. drying in air at ambient temperatures. These changes depend on the severity of drying, whether ambient or forced oven drying, and are to some extent reversible. A spin-diffusion model was constructed using dimensions obtained from Xray diffraction, comparisons between predictions and experimental data from an NMR study showed that the location of water was dependent on the moisture history of wood. In the green state, at least some of the water in the wood cell wall forms a layer, between the cellulose crystals and the hemicellulose and lignin matrix. If dried and then rewet, this water associated with the cellulose crystals was not present to the same degree as in the green state, allowing a closer association of the hemicellulose with the cellulose. The effect of this change in water distribution in the wood cell wall on the bulk mechanical wood properties was shown in mechanical testing. The nanostructure of the wood cell wall therefore should be considered to contain cellulose, hemicellulose, lignin and water, where each component contributes, according to its molecular properties, dynamic mechanical properties which are reflected in the bulk material properties.</p>

Effects of Sodium Salt on Hot Mechanical Properties and Microstructure of MgO-Al-C Bricks

2013 ◽  
Vol 690-693 ◽  
pp. 662-665
Author(s):  
Jun Cong Wei ◽  
Xiu Mei Ji ◽  
Jian Kun Huang ◽  
Chun Hui Gao ◽  
Jun Bo Tu
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Electron Microscope ◽  
Silicon Powder ◽  
Modulus Of Rupture ◽  
Graphite Flake ◽  
X Ray Diffraction ◽  
X Ray ◽  
Al Powder ◽  
Scanning Electron

The effects of addition of silicon powder (1 wt. %) and Na2CO3 (converting to additional 0.5%, 1% Na2O) on the hot modulus of rupture (HMOR) of MgO-Al-C bricks were investigated. MgO-Al-C refractories were prepared by using fused magnesia and graphite flake as main starting materials, and Si, Na2CO3 or both as additives. Its phase composition and microstructure were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and EDS. The results showed that the HMOR of MgO-Al-C bricks increased slightly with addition of Si powder. However, the HMOR decreased when adding Na2CO3 and Si powder together. Moreover, the HMOR deduced with the increase of Na2CO3 content. The mechanism is that Al powder reacted to form fibrous Al4C3 and AlN, which could improve the HMOR. When silicon was added, β-SiC and M2S were formed, which could fill the passages and pores. So the densification and strength were improved. The addition of Na2CO3 could promote the oxidation of Al powder to form Al2O3, and inhibit the formation of Al4C3 and AlN. Hence the strength of MgO-Al-C deduced.

scholarly journals Comparative studies on the mechanical properties and microstructures of outerwood and corewood in Pinus radiata D. Don

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Ming-yue Li ◽  
Hai-qing Ren ◽  
Yu-rong Wang ◽  
Ying-chun Gong ◽  
Yong-dong Zhou
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cell Wall ◽  
Crystallite Size ◽  
Wall Thickness ◽  
Pinus Radiata ◽  
Microfibril Angle ◽  
Cell Wall Thickness ◽  
Modulus Of Rupture ◽  
Relative Crystallinity

AbstractTwenty-year-old Pinus radiata trees imported from New Zealand were investigated, and a comparison was made between the outerwood (rings 16–20) and corewood (rings 4–6) in terms of mechanical properties, anatomical characteristics, microfibril angle (MFA), relative crystallinity, crystallite size and lignin content to determine the relationship between their mechanical properties and microstructures. The results demonstrated that the mechanical properties of the Pinus radiata outerwood were significantly better than those of the corewood. The outerwood had a modulus of rupture (MOR) of 106 MPa, a modulus of elasticity (MOE) of 11.4 GPa, and compressive strength parallel to the grain of 38.7 MPa, and the MOR, MOE and compressive strength parallel to the grain of the corewood were 78.9 MPa, 7.12 GPa and 29.3 MPa, respectively. The observed microstructures of the Pinus radiata outerwood and corewood were different, mainly due to differences in cell wall thickness, MFA, and relative crystallinity. The double wall thickness of the tracheid cells of the corewood and outerwood were 3.65 and 5.02 µm, respectively. The MFA data indicated that the average MFA of the outerwood was 14.0°, which was smaller than that of the corewood (22.3°). With X-ray diffraction, the relative crystallinity of the corewood was determined to be 35.7%, while that of the outerwood was 40.2%. However, the crystallite size of the outerwood cell wall shows no obvious difference from that of the corewood. Imaging FTIR spectroscopy showed a slightly higher relative content of lignin in the cell wall of the outerwood. The correlation between the microstructures and mechanical properties showed that the corewood with a thin cell wall, large MFA and low relative crystallinity had poor mechanical properties, while the outerwood with a thicker tracheid, smaller MFA and higher relative crystallinity had better mechanical properties. This means that the MFA, relative crystallinity and cell wall thickness synergically affect the mechanical properties of Pinus radiata in different radial locations.

scholarly journals Mechanical properties of the fiber cell wall in Bambusa pervariabilis bamboo and analyses of their influencing factors

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 5316-5327
Author(s):  
Bo Zhang ◽  
Yihan Guo ◽  
Xing'e Liu ◽  
Huiyu Chen ◽  
Shumin Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Microfibril Angle ◽  
Fiber Cell ◽  
X Ray Diffraction ◽  
Important Indicator ◽  
Different Ages ◽  
Bamboo Fibers ◽  
Fiber Cell Wall ◽  
Cell Wall Mechanics

The cell wall mechanical properties are an important indicator for evaluating the overall mechanical properties of natural bamboo fibers. Using the nanoindentation technique, the variation of the mechanical properties of the fiber cell wall of Bambusa pervariabilis culms with different ages and different positions (both radial and longitudinal) was studied. Moreover, x-ray diffraction (XRD) was employed to measure the microfibril angle (MFA), and the correlation between the MFA and the mechanical properties of the fiber cell wall. The results showed that there was a remarkable difference in the fiber cell wall mechanical properties at different ages and at different radial and longitudinal positions. However, at different ages and at different positions, the absolute value of variation of MFA was less than 1° and was very minor. Furthermore, there was no significant correlation between the fiber cell wall mechanics and MFA, indicating that the mechanical property of the fiber cell walls might be synergistically affected by many factors.

scholarly journals Water in Pinus Radiata Wood Secondary Cell Walls: An Investigation Using Nuclear Magnetic Resonance and Synchrotron X-Ray Diffraction

2021 ◽  
Author(s):  
◽  
Stefan James Hill
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Wood Cell Wall ◽  
Chemical Components ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
Green State ◽  
Nmr Study ◽  
Cellulose Crystals

<p>The mechanical properties of wood allow it to be used for numerous purposes. For most purposes, drying of the wood material from the green state, sawn from the log, is first required. This drying step significantly improves the strength properties of wood. It is therefore clear that moisture in wood plays an important role in determining the bulk mechanical properties. Over the last century, many studies have been carried out to investigate the way in which the water content wood affects the bulk mechanical properties. More recent studies have focused to the individual chemical components that make up wood to understand the observed changes in bulk mechanical properties. Models of the nanostructure of wood contained; cellulose, hemicellulose, and lignin, and the arrangement and location of these components in terms of their mechanical properties was interpreted through what was described as the 'slip-stick' mechanism, by which wood, in its green state, maintained its molecular and mechanical properties under external stresses. This model, while insightful, failed to account for the presence and the role of water in the nanostructure of wood. In this work, synchrotron based X-ray diffraction and NMR studies, have been used to develop a new model, in which water plays a vital role in the determination of the mechanical properties of wood in its green, part-dried, and rewet states. X-ray diffraction showed that changes occur to the molecular packing of cellulose crystallites with change in moisture content, and that these changes begin to occur under mild drying conditions, i.e. drying in air at ambient temperatures. These changes depend on the severity of drying, whether ambient or forced oven drying, and are to some extent reversible. A spin-diffusion model was constructed using dimensions obtained from Xray diffraction, comparisons between predictions and experimental data from an NMR study showed that the location of water was dependent on the moisture history of wood. In the green state, at least some of the water in the wood cell wall forms a layer, between the cellulose crystals and the hemicellulose and lignin matrix. If dried and then rewet, this water associated with the cellulose crystals was not present to the same degree as in the green state, allowing a closer association of the hemicellulose with the cellulose. The effect of this change in water distribution in the wood cell wall on the bulk mechanical wood properties was shown in mechanical testing. The nanostructure of the wood cell wall therefore should be considered to contain cellulose, hemicellulose, lignin and water, where each component contributes, according to its molecular properties, dynamic mechanical properties which are reflected in the bulk material properties.</p>

Observation of pseudo 10-fold symmetry in the ordered iron-zinc delta phase

1992 ◽  
Vol 50 (1) ◽  
pp. 36-37
Author(s):  
L. A. Giannuzzi ◽  
A. S. Ramani ◽  
P. R. Howell ◽  
H. W. Pickering ◽  
W. R. Bitler
Keyword(s):  
Single Phase ◽  
X Ray Diffraction ◽  
Rich Region ◽  
Average Cell ◽  
X Ray ◽  
Delta Phase ◽  
Cell Dimensions ◽  
Δ Phase ◽  
Morphological Differences ◽  
Concentration Discontinuity

The δ phase is a Zn-rich intermetallic, having a composition range of ∼ 86.5 - 92.0 atomic percent Zn, and is stable up to 665°C. The stoichiometry of the δ phase has been reported as FeZn7 and FeZn10 The deviation in stoichiometry can be attributed to variations in alloy composition used by each investigator. The structure of the δ phase, as determined by powder x-ray diffraction, is hexagonal (P63mc or P63/mmc) with cell dimensions a = 1.28 nm, c = 5.76 nm, and 555±8 atoms per unit cell. Later work suggested that the layer produced by hot-dip galvanizing should be considered as two distinct phases which are characterized by their morphological differences, namely: the iron-rich region with a compact appearance (δk) and the zinc-rich region with a columnar or palisade microstructure (δp). The sub-division of the δ phase was also based on differences in diffusion behavior, and a concentration discontinuity across the δp/δk boundary. However, work utilizing Weisenberg photographs on δ single crystals reported that the variation in lattice parameters with composition was small and hence, structurally, the δk phase and the δp phase were the same and should be thought of as a single phase, δ. Bastin et al. determined the average cell dimensions to be a = 1.28 nm and c = 5.71 nm, and suggested that perhaps some kind of ordering process, which would not be observed by x-ray diffraction, may be responsible for the morphological differences within the δ phase.

Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials

2019 ◽  
Vol 107 (2) ◽  
pp. 207 ◽  
Author(s):  
Jaroslav Čech ◽  
Petr Haušild ◽  
Miroslav Karlík ◽  
Veronika Kadlecová ◽  
Jiří Čapek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Young’S Modulus ◽  
Milling Time ◽  
Young's Modulus ◽  
Element Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Particles ◽  
Complete Homogenization

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.

scholarly journals Enhancement of Chloroprene/Natural/Butadiene Rubber Nanocomposite Properties Using Organoclays and Their Combination with Carbon Black as Fillers

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1085
Author(s):  
Patricia Castaño-Rivera ◽  
Isabel Calle-Holguín ◽  
Johanna Castaño ◽  
Gustavo Cabrera-Barjas ◽  
Karen Galvez-Garrido ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
High Performance ◽  
Rubber Matrix ◽  
Butadiene Rubber ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rubber Blends ◽  
Ft Ir ◽  
Chloroprene Rubber

Organoclay nanoparticles (Cloisite® C10A, Cloisite® C15) and their combination with carbon black (N330) were studied as fillers in chloroprene/natural/butadiene rubber blends to prepare nanocomposites. The effect of filler type and load on the physical mechanical properties of nanocomposites was determined and correlated with its structure, compatibility and cure properties using Fourier Transformed Infrared (FT-IR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and rheometric analysis. Physical mechanical properties were improved by organoclays at 5–7 phr. Nanocomposites with organoclays exhibited a remarkable increase up to 46% in abrasion resistance. The improvement in properties was attributed to good organoclay dispersion in the rubber matrix and to the compatibility between them and the chloroprene rubber. Carbon black at a 40 phr load was not the optimal concentration to interact with organoclays. The present study confirmed that organoclays can be a reinforcing filler for high performance applications in rubber nanocomposites.

scholarly journals The Potential for Natural Stones from Northeastern Brazil to Be Used in Civil Construction

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 440
Author(s):  
Fabiana Pereira da Costa ◽  
Jucielle Veras Fernandes ◽  
Luiz Ronaldo Lisboa de Melo ◽  
Alisson Mendes Rodrigues ◽  
Romualdo Rodrigues Menezes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Chemical Resistance ◽  
Mechanical Analysis ◽  
Northeastern Brazil ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Agents ◽  
Natural Stones

Natural stones (limestones, granites, and marble) from mines located in northeastern Brazil were investigated to discover their potential for use in civil construction. The natural stones were characterized by chemical analysis, X-ray diffraction, differential thermal analysis, and optical microscopy. The physical-mechanical properties (apparent density, porosity, water absorption, compressive and flexural strength, impact, and abrasion) and chemical resistance properties were also evaluated. The results of the physical-mechanical analysis indicated that the natural stones investigated have the potential to be used in different environments (interior, exterior), taking into account factors such as people’s circulation and exposure to chemical agents.

scholarly journals Functional Bionanocomposite Fibers of Chitosan Filled with Cellulose Nanofibers Obtained by Gel Spinning

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1563
Author(s):  
Sofia Marquez-Bravo ◽  
Ingo Doench ◽  
Pamela Molina ◽  
Flor Estefany Bentley ◽  
Arnaud Kamdem Tamo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Cellulose Nanofibers ◽  
Microstructural Characterization ◽  
Fiber Formation ◽  
Fiber Direction ◽  
Composite Fibers ◽  
X Ray Diffraction ◽  
Gel Spinning ◽  
X Ray

Extremely high mechanical performance spun bionanocomposite fibers of chitosan (CHI), and cellulose nanofibers (CNFs) were successfully achieved by gel spinning of CHI aqueous viscous formulations filled with CNFs. The microstructural characterization of the fibers by X-ray diffraction revealed the crystallization of the CHI polymer chains into anhydrous chitosan allomorph. The spinning process combining acidic–basic–neutralization–stretching–drying steps allowed obtaining CHI/CNF composite fibers of high crystallinity, with enhanced effect at incorporating the CNFs. Chitosan crystallization seems to be promoted by the presence of cellulose nanofibers, serving as nucleation sites for the growing of CHI crystals. Moreover, the preferential orientation of both CNFs and CHI crystals along the spun fiber direction was revealed in the two-dimensional X-ray diffraction patterns. By increasing the CNF amount up to the optimum concentration of 0.4 wt % in the viscous CHI/CNF collodion, Young’s modulus of the spun fibers significantly increased up to 8 GPa. Similarly, the stress at break and the yield stress drastically increased from 115 to 163 MPa, and from 67 to 119 MPa, respectively, by adding only 0.4 wt % of CNFs into a collodion solution containing 4 wt % of chitosan. The toughness of the CHI-based fibers thereby increased from 5 to 9 MJ.m−3. For higher CNFs contents like 0.5 wt %, the high mechanical performance of the CHI/CNF composite fibers was still observed, but with a slight worsening of the mechanical parameters, which may be related to a minor disruption of the CHI matrix hydrogel network constituting the collodion and gel fiber, as precursor state for the dry fiber formation. Finally, the rheological behavior observed for the different CHI/CNF viscous collodions and the obtained structural, thermal and mechanical properties results revealed an optimum matrix/filler compatibility and interface when adding 0.4 wt % of nanofibrillated cellulose (CNF) into 4 wt % CHI formulations, yielding functional bionanocomposite fibers of outstanding mechanical properties.

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