scholarly journals Mechanical properties and water resistance of Vietnamese acacia and rubberwood after thermo-hygro-mechanical modification

2020 ◽  
Vol 78 (5) ◽  
pp. 841-848
Author(s):  
Rulong Cao ◽  
Juhani Marttila ◽  
Veikko Möttönen ◽  
Henrik Heräjärvi ◽  
Pekka Ritvanen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Compression Strength ◽  
Mechanical Performance ◽  
Brinell Hardness ◽  
Water Immersion ◽  
Dry Density ◽  
Fast Growing ◽  
Subsequent Thermal Treatment ◽  
Reference Specimens

Abstract Low density and poor mechanical performance often limit utilisation of sawn wood from fast-growing plantation forests. Thermo-hygro-mechanical modification (THM) of timber is one innovation for improving the properties of light-weight wood species. The objective of this study was to determine the effects of THM and subsequent thermal treatment on dry density, modulus of elasticity (MOE), compression strength, Brinell hardness, and swelling behaviour in immersion tests on two fast-growing Vietnamese species, acacia (Acacia mangium) and rubberwood (Hevea brasiliensis). Test boards were modified in an industrial kiln, in which a tangential thickness compression of 14% and 12% were aimed for acacia and rubberwood, respectively, either with or without subsequent thermal treatment at 210 °C. Dry density, MOE, Brinell hardness, compression strength, and dimensional changes in water immersion tests of specimens were measured from the modified and unmodified reference materials, the latter ones being kiln dried at 50 °C. The results showed that the responses of the mechanical properties were more evident for rubberwood than for acacia. In rubberwood, the MOE and compression strength of wood thermo-hygro-mechanically modified with or without thermal treatment were higher than those of kiln-dried reference specimens throughout the thickness profile. In case of acacia, similar differences between the modified and reference specimens were observed only in the surface layer. Density and Brinell hardness of thermo-hygro-mechanically modified rubberwood were higher than those of reference specimens, but after thermal treatment they did not differ from (acacia) or were lower (rubberwood) than those of THM specimens. Post-compression thermal treatment increased the hydrophobicity of THM specimens.

scholarly journals Effects of thermal modification on physical and mechanical properties of Mozambican Brachystegia spiciformis and Julbernardia globiflora wood

2020 ◽  
Vol 78 (5) ◽  
pp. 871-878
Author(s):  
Feliz Nhacila ◽  
Eunice Sitoe ◽  
Ernesto Uetimane ◽  
Alberto Manhica ◽  
Andrade Egas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Mass Loss ◽  
Compression Strength ◽  
Tree Species ◽  
Wood Properties ◽  
Thermal Modification ◽  
Dry Density ◽  
Treatment Level ◽  
Brachystegia Spiciformis

Abstract Mozambique’s large pool of tropical hardwoods is hampered by the prevalence of low-grade tree species along with a lack of cost-effective processing technologies to improve timber properties. Brachystegia spiciformis and Julbernadia globiflora are the most abundant tree species in terms of volume in the country, but with limited use due to their low timber quality. In this study, thermal modification at three different temperatures (215 °C; 230 °C; 245 °C) was applied for 2 h to the timber of both species, followed by measurement of a set of physical and mechanical wood properties. The results show that the originally light-coloured sapwood of both tree species darkened gradually as the intensity of thermal modification increased. Additionally, from untreated samples to the highest thermal treatment level, timber of B. spiciformis incurred a maximum mass loss of 27%, while oven-dry density was reduced from 0.65 to 0.56 g/cm3 and equilibrium moisture content (EMC) changed from 7 to 3%. Timber of J. globiflora had a mass loss of 23% after the highest treatment level, an oven-dry density reduction of 0.81 to 0.74 g/cm3 and an EMC decrease from 8 to 3%. The changes in mechanical properties from reference samples to the highest thermal treatment level were also significant. For B. spiciformis, MOE decreased by 10.2%, MOR by 50.8%, compression strength parallel to the grain by 29.2% and Brinell hardness by 23.5%. Timber of J. globiflora followed the same trend with an MOE decrease by 6.9%, an MOR decrease by 53.2% and a decrease in compression strength parallel to the grain by 21.9%. All tested wood properties showed significant responses to thermal modification after the most intensive treatment level had been applied. Despite the degradation of mechanical properties in both species, an optimal combination of temperature and treatment time could be achieved. The recorded changes of the tested wood properties in both species could increase the range of applications; the new colour resembled that of highly sought-after tropical hardwoods.

Anatomical, Chemical and Mechanical Properties of Fast-Growing Populus × Euramericana cv. ‘74/76’

IAWA Journal ◽  
2014 ◽  
Vol 35 (2) ◽  
pp. 158-169 ◽  
Author(s):  
Zhao Rongjun ◽  
Yao Chunli ◽  
Cheng Xianbao ◽  
Lu Jianxiong ◽  
Fei Benhua ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Sandy Loam ◽  
Physical And Mechanical Properties ◽  
Wood Properties ◽  
Planting Density ◽  
Dry Density ◽  
Growth Rings ◽  
Fast Growing ◽  
Breast Height ◽  
Large Growth

The anatomical characteristics, chemical composition, and physical and mechanical properties of fast-growing Populus × euramericana cv. ‘74/76’ juvenile wood were investigated. Four- to five-year-old clonal plantation trees were harvested from two different experimental sites in the suburbs of Beijing. The Shunyi site had black alkali soil with a planting density of 4 × 6 m and the Miyun site had sandy loam soil with a planting density of 3 × 5 m. The test results showed that the poplar trees from the two sites were both fast growing, with poplar at Shunyi growing faster than at Miyun. There were no significant differences in wood properties between trees grown at the two sites. Fiber length at breast height varied from 872 to 1300 μm between growth rings, average fiber width varied from 21.0 to 25.5 μm and double wall thickness varied from 5.0 to 6.6 μm. Average cellulose, lignin and hemicellulose contents in the samples were 48.9%, 25.4%, and 18.8%, respectively. MFA was higher in the first two growth rings (20–25°), and then decreased rapidly to 12° close to the bark. The average air-dry density at breast height was 401 kg/m3 while the average MOE at breast height was 9.3 GPa. The trees showed large growth rates in both height and stem diameter during the growing season. However, wood properties of the juvenile poplar appeared to be similar to those of poplars with a slower growth rate.

Comparison of mechanical properties of thermally modified wood at growth ring and cell wall level by means of instrumented indentation tests

Holzforschung ◽  
2009 ◽  
Vol 63 (4) ◽  
Author(s):  
Stefanie Stanzl-Tschegg ◽  
Wilfried Beikircher ◽  
Dieter Loidl
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Thermal Treatment ◽  
Mechanical Performance ◽  
Growth Ring ◽  
Beech Wood ◽  
Thermal Modification ◽  
Wood Structure ◽  
Instrumented Indentation ◽  
Indentation Tests

Abstract Thermal modification is a well established method to improve the dimensional stability and the durability for outdoor use of wood. Unfortunately, these improvements are usually accompanied with a deterioration of mechanical performance (e.g., reduced strength or higher brittleness). In contrast, our investigations of the hardness properties in the longitudinal direction of beech wood revealed a significant improvement with thermal modification. Furthermore, we applied instrumented indentation tests on different hierarchical levels of wood structure (growth ring and cell wall level) to gain closer insights on the mechanisms of thermal treatment of wood on mechanical properties. This approach provides a variety of mechanical data (e.g., elastic parameters, hardness parameters, and viscoelastic properties) from one single experiment. Investigations on the influence of thermal treatment on the mechanical properties of beech revealed similar trends on the growth ring as well as the on the cell wall level of the wood structure.

scholarly journals Modification of Lattice Structures and Mechanical Properties of Metallic Materials by Energetic Ion Irradiation and Subsequent Thermal Treatments

2020 ◽  
Vol 4 (1) ◽  
pp. 17 ◽  
Author(s):  
Akihiro Iwase ◽  
Fuminobu Hori
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloys ◽  
Thermal Treatment ◽  
Intermetallic Compounds ◽  
Ion Irradiation ◽  
High Energy ◽  
Industrial Applications ◽  
The Other ◽  
Lattice Structures ◽  
Subsequent Thermal Treatment

When materials are irradiated with high-energy ions, their energies are transferred to electrons and atoms in materials, and the lattice structures of the materials are largely changed to metastable or non-thermal equilibrium states, causing the modification of several physical properties. There are two processes for the material modification by ion irradiation; one is “the irradiation-enhanced process”, and the other is “the irradiation-induced process”. In this review, two kinds of recent results for the microstructural changes and the modifications of mechanical properties will be summarized: one is the hardness modification of dilute aluminum alloys, which is a result of the irradiation-enhanced process, and the other is the hardness modification of Ni-based intermetallic compounds as a result of the irradiation-induced process. The effect of the subsequent thermal treatment on the microstructures and the hardness for ion-irradiated dilute aluminum alloys is quite different from that for Ni-based intermetallic compounds. This result reflects the difference between the irradiation-enhanced process and the irradiation-induced process. Finally, possibilities of the ion irradiation and subsequent thermal treatment to industrial applications will also be discussed.

Effects of Temperature on Mechanical Performance of Elastocoast® PUR-Stone

2011 ◽  
Vol 250-253 ◽  
pp. 3025-3028
Author(s):  
Bin Zhang ◽  
Li Jia Liu ◽  
Gui Ying Liu
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Compression Strength ◽  
Mechanical Performance ◽  
Cold Region ◽  
Effects Of Temperature

This thesis provides a study and analysis of the flexural strength, compression strength of Elastocoast® PUR-stone which is effected by temperature .Through seven tests we find that temperature does not exert any major impact on physics and mechanical properties of Elastocoast® PUR-stone . This tests provide the reliable guidance for cold region engineering.

scholarly journals Wood Quality Characterization of Sycamore Maple (Acer pseudoplatanus L.) and its Utilization in Wood Products Industries

2021 ◽  
Vol 42 (3) ◽  
Author(s):  
Tomislav Sedlar ◽  
Bogoslav Šefc ◽  
Srđan Stojnić ◽  
Tomislav Sinković
Keyword(s):  
Mechanical Properties ◽  
Compression Strength ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Wood Quality ◽  
Beech Wood ◽  
Wood Products ◽  
Dry Density ◽  
Acer Pseudoplatanus ◽  
Sycamore Maple

This study quantified the physical and mechanical properties of sycamore maple (Acer pseudoplatanus L.) as a basis for assessing wood quality. The physical properties of oven-dry density, density at 12% MC, green density, basic density, longitudinal, radial, tangential and volumetric shrinkages were tested and the mechanical properties of bending strength, modulus of elasticity at bending, compression strength parallel to grain and compression strength in radial and tangential direction as well as of Brinell hardness on the cross, radial, and tangential section were determined. Five sycamore maple trees from Medvednica region were selected for the purposes of this research. The results were compared with known literature data on sycamore maple wood, beech wood from the same sight, and beech wood from Gorski Kotar region. For a better understanding of sycamore maple physiology, as well as for assessing the quality of wood products, the distribution of wood properties within the tree radius, from pith to bark, was investigated. There was a general bell shaped distribution, in the radial direction, in wood density, and mechanical properties of sycamore maple wood. Shrinkages decreased from pith to bark, except for tangential shrinkage with bell shaped pattern. All investigated wood densities of sycamore maple from Medvednica were similar to the findings of studies known in literature, as well as shrinkages, except for the lower longitudinal shrinkage. Investigated mechanical properties of sycamore maple wood were similar to the findings of studies known in literature, except for the lower bending strength and modulus of elasticity (MOE). Investigated sycamore maple indicated better dimensional stability than beech wood from two locations in the region, although it did not match the beech wood regarding mechanical properties, especially wood hardness.

Quasi-static and dynamic nanoindentation to determine the influence of thermal treatment on the mechanical properties of bamboo cell walls

Holzforschung ◽  
2015 ◽  
Vol 69 (7) ◽  
pp. 909-914 ◽  
Author(s):  
Yanjun Li ◽  
Liping Yin ◽  
Chengjian Huang ◽  
Yujie Meng ◽  
Feng Fu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Thermal Treatment ◽  
Cell Walls ◽  
Loss Modulus ◽  
Treatment Temperature ◽  
Dry Density ◽  
Bamboo Fibers ◽  
Tan Δ ◽  
Dynamic Nanoindentation

Abstract Bamboo was thermally treated at 180°C and 200°C, and the micromechanical properties of its cell walls were investigated by means of quasi-static and dynamic nanoindentation experiments. With increasing treatment temperatures, the average dry density and mass of the bamboo decreased, whereas the already reduced elastic modulus at 180°C of the fiber cell walls did not change, but the hardness showed increasing tendencies. Dynamic nanoindentation revealed reduced storage modulus $({E'_{\rm{r}}})$ and loss modulus $({E''_{\rm{r}}}\,)$ for the thermotreated bamboo cell walls compared with the untreated bamboo fibers in all frequency regions. Moreover, ${E'_{\rm{r}}},{\rm{ }}{E''_{\rm{r}}},$ and loss tangent (tan δ) of treated bamboo decreased with increasing treatment temperature.

scholarly journals Mechanical and Durability Properties of Lightweight Foamed Concrete Containing Palm Kernel Shell

2018 ◽  
Vol 7 (3.9) ◽  
pp. 65 ◽  
Author(s):  
Hanizam Awang ◽  
Adebayo Adeshina Dauda ◽  
Wenny Arminda
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Mechanical Strength ◽  
Mechanical Performance ◽  
Palm Kernel ◽  
Dry Density ◽  
Palm Kernel Shell ◽  
Durability Properties ◽  
Foamed Concrete ◽  
Strength And Durability

The research project aimed to investigate the effect of palm kernel shell (PKS) on the mechanical strength and durability of foamed concrete at the level of 10% to 60%. The samples were designed and prepared having a dry density of 1600 kg/m3with a binder to filler ratio of 1:1.2. Hardened foamed concrete samples were subjected to air cured and tested at the age of 7, 14, 28, 56 and 90 days. Mechanical performance of the PKS foamed concrete was assessed in term of its compressive strength. Durability properties namely water absorption and vacuum porosity were investigated. The result shows that the addition of PKS to lightweight foamed concrete up to 30% significantly improve the mechanical properties and the durability of the foamed concrete.  

scholarly journals Towards Functional Parts by Binder Jetting Calcium-Sulphate with Thermal Treatment Post-Processing

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3818
Author(s):  
María Ángeles Castro-Sastre ◽  
Ana Isabel Fernández-Abia ◽  
Janik Piep ◽  
Pablo Rodríguez-González ◽  
Joaquín Barreiro
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Compression Strength ◽  
Calcium Sulphate ◽  
Infrared Analysis ◽  
Great Chance ◽  
Good Surface ◽  
Weight Variation ◽  
Functional Components ◽  
Binder Jetting

The objective of our research is to improve the properties of calcium-sulphate hemihydrate parts printed by binder jetting. In this paper, we show the thermal treatment results when using temperature time ramps on binder-jetted ceramic parts without infiltrating. The results show that the mechanical properties of printed parts are improved substantially. Two different thermal cycles were investigated for their effect on the dehydration process of CaSO4·½H2O using infrared analysis. The thermal-treated samples were compared with respect to porosity, surface roughness, compression strength and dimensional and weight variation. The proposed thermal treatment significantly improves the compression strength in a short time, guaranteeing dimensional stability while providing a good surface. This improvement in mechanical properties offers a great chance for using binder-jetted parts as functional components, for example, in the casting field or the medical sector (scaffolds).

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