Effects of accelerated weathering test on the properties of larch wood

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7400-7415
Author(s):  
Liting Cheng ◽  
Yajing Di ◽  
Peng Zhao ◽  
Jian Dai ◽  
Zhiguo Yang ◽  
...  
Keyword(s):  
Modulus Of Elasticity ◽  
Wood Properties ◽  
Sem Analysis ◽  
Accelerated Weathering ◽  
Electron Microscopic ◽  
Larch Wood ◽  
Light Yellow ◽  
Accelerated Weathering Test ◽  
Preset Time ◽  
The Relationship

To investigate the changes of larch wood properties under the influence of long-standing exposure to the environment, the QUV accelerated weathering tester (fluorescent UV and condensation testers) was used to accelerate the weathering of wood within a given preset time, and the changes were studied by analogue simulation. The wood color changed noticeably under different weathering time, and it gradually darkened from light yellow to deep reddish brown. Scanning electron microscopic (SEM) analysis revealed that as the weathering time increased, the cell wall was broken, the pits were cracked, and the tracheids were damaged. The results of the energy spectrum analysis (O/C (oxygen/carbon)) showed an increasing trend in the ratio, indicating that the wood underwent an oxidation reaction induced by light. From the values of the two testing indexes and their change patterns with weathering time, the same trend was observed, with the values of modulus of elasticity (MOE) in static bending being greater than that in dynamic bending Ed (the dynamic modulus of elasticity). However, the variability of MOE was greater than that of Ed. A comparative analysis of the two detection indicators was performed. The relationship between the proposed combined correction Ed and weathering time was: y = 0.0000001017 t2 – 0.0006 t + 9.77.

scholarly journals Evaluation of Bent Trees in Juvenile Teak (Tectona grandis L.f.) Plantations in Costa Rica: Effects on Tree Morphology and Wood Properties

2017 ◽  
Author(s):  
Nancy Guzmán ◽  
Róger Moya ◽  
Olmán Murillo
Keyword(s):  
Costa Rica ◽  
Modulus Of Elasticity ◽  
Morphological Characteristics ◽  
Tectona Grandis ◽  
Wood Properties ◽  
Early Years ◽  
Chemical Compositions ◽  
Variable Diameter ◽  
Morphological Variables ◽  
The Relationship

Bent trees have been observed during the early years in juvenile plantations (less than 5 years-old) of Tectona grandis in Costa Rica. The relationship between bending and the morphological characteristics of the trees was explored. An evaluation of bent trees was conducted in six juvenile plantations (8, 17, 27, 28, 31, and 54 months old) of Tectona grandis. Site 1 with 8-month-old plantations did not display any relationship with any tree morphological variable (diameter, height, and crown weight of tree), whereas for the sites 2, 3, and 4 with 17-, 27-, and 28-month-old plantations, respectively, all the tree morphological variables were statistically correlated with the bent trees. A multiple regression analysis showed that the most influential variables were height to crown base, crown weight, diameter, and total height of the tree. An evaluation of the bending risk factor (RF) was correlated with the height to crown base, crown weight, and form factor. The modulus of elasticity and chemical compositions of bent trees differed from those of straight trees. The causes of tree bending are complex, involving, among other factors, the morphology of the trees, plantation conditions, and other factors specific to the xylem, such as the specific gravity, modulus of elasticity, and presence of calcium and magnesium in the wood.

Effect of Defect Characteristics on the Color of BaTiO3-Based PTC Ceramic

2016 ◽  
Vol 697 ◽  
pp. 243-247 ◽  
Author(s):  
Ai Mei Yang ◽  
Jian Ming Deng ◽  
Cong Xue Su ◽  
Wen Hao Jia ◽  
Lai Jun Liu
Keyword(s):  
Sem Analysis ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Electron Probe Micro Analyzer ◽  
Scanning Electron Microscopic ◽  
Temperature Measurement System ◽  
The Relationship ◽  
Structure And Microstructure ◽  
Similar Elements

The barium titanium based PTC ceramic with two kind of colors, light blue and yellow, were obtained by changing sintering processing. In order to reveal the relationship between color and electrical properties of the ceramics. The phase structure and microstructure of as synthesized samples were investigated by powder X-ray diffraction (XRD) and scanning electron microscopic (SEM) analysis. The micro area elements were characterized by electron probe micro-analyzer (EPMA) and x-ray photoelectron spectrometer (XPS). The thermo-sensitive properties were studied by resistance-temperature measurement system. The results reveal that two kinds of PTC ceramics have the same structure, similar elements, but different microstructure and valence concentration of titanium. It is suggested that difference of color of the PTC ceramics are originated from the defect concentration of titanium.

scholarly journals Prediction of Maritime Pine Boards Modulus of Elasticity by Means of Sonic Testing on Green Timber

2021 ◽  
Vol 11 (4) ◽  
pp. 1748
Author(s):  
Giovanna Concu
Keyword(s):  
Modulus Of Elasticity ◽  
Structural Timber ◽  
Maritime Pine ◽  
Manufacturing Costs ◽  
Sonic Waves ◽  
Wet Condition ◽  
Structural Grade ◽  
The Relationship ◽  
Grade Yield

Timber buildings are experiencing a rapid diffusion due to their good performance and their sustainability; however, some steps of structural timber production process, such as drying, are energy-intensive and environmentally impactful, and many wood species are also affected by low yield. Therefore, it would be important to determine the quality of the green material, that is, in wet condition, before undergoing the most impactful and expensive production steps. This paper describes a research aimed at quantifying the variation of the dynamic modulus of elasticity MoEdyn, which is commonly used for structural timber mechanical grading, from wet to dry condition in Sardinian maritime pine boards to be used for the production of laminated timber, and to examine the relationship between wet and dry MoEdyn. The MoEdyn was determined from measurements of the velocity of sonic waves propagating through the boards. The results show that the dry MoEdyn can be estimated starting from boards sonic testing in the wet condition, so providing a basis for implementing Sardinian maritime pine pre-grading in order to obtain the reduction of manufacturing costs, the abatement of environmental impact, and the increase of structural grade yield.

scholarly journals Preparation and characterization of corn starch/PVA/glycerol composite films incorporated with ε-polylysine as a novel antimicrobial packaging material

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 154-161 ◽  
Author(s):  
Gao Yurong ◽  
Li Dapeng
Keyword(s):  
Water Solubility ◽  
Corn Starch ◽  
Composite Films ◽  
Antimicrobial Properties ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Packaging Material ◽  
Hydroxyl Group ◽  
Electron Microscopic ◽  
Antimicrobial Packaging

AbstractCorn starch/polyvinyl alcohol (PVA)/glycerol composite films incorporated with ε-polylysine were prepared, and their properties were investigated. The Fourier-transform infrared (FTIR) spectroscopy indicated that the interactions happened between the amino group of ε-polylysine and hydroxyl group starch/PVA composite films. X-ray diffraction (XRD) analysis showed that the addition of ε-polylysine decreased the intensity of all crystal peaks. Thermogravimetric (TGA) analysis suggested that ε-polylysine improved the thermal stability of composite films. Scanning electron microscopic (SEM) analysis showed that the upper surface of composite films incorporated with ε-polylysine presented more compact and flat surface. The antimicrobial activity of the composite film progressively increased with the increasing of ε-polylysine concentration (P < 0.05). The tensile strength, elongation at break and water absorption significantly increased, whereas water solubility decreased with the increasing of ε-polylysine concentration (P < 0.05). Therefore, the corn starch/PVA/glycerol composite films incorporated with ε-polylysine had good mechanical, physical and antimicrobial properties and could have potential application as a novel antimicrobial packaging material.

Some Tree Growth – Wood Property Relationships of Eucalypts

1975 ◽  
Vol 5 (3) ◽  
pp. 424-432 ◽  
Author(s):  
J. E. Nicholson ◽  
W. E. Hillis ◽  
N. Ditchburne
Keyword(s):  
Wood Property ◽  
Basic Density ◽  
Wood Properties ◽  
Reaction Wood ◽  
Growth Strain ◽  
Fiber Structure ◽  
Tree Crown ◽  
Stem Form ◽  
The Relationship ◽  
Longitudinal Growth Strain

The relationship between level of longitudinal growth strain and stress, modulus of elasticity, basic density, volumetric shrinkage, fiber classification, and stem form was investigated with 10 Eucalyptusregnans regrowth trees. Close relationships were observed. It is suggested that variations in these properties within trees are closely controlled, possibly to enable optimum positioning of the tree crown in relation to its immediate environment. The concept of fiber structure varying as a response to environment is supported by the observed variation in wood properties within and between trees of this species. The often-reported association between eccentric radial growth and reaction wood was not substantiated in this study.The data indicate that if economically justifiable, it would be possible to segregate trees that are likely to contain material that is hard to season.

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