WOOD RESEARCH Volume 68, Number 4, 2023
HARUNA SEIDU, RÓBERT NÉMETH, Francis Wilson Owusu, PROSPER MENSAH, MICHAEL AWOTWE-MENSAH, and BOAKYE FELIX

EFFECT OF TEMPERATURE AND RELATIVE HUMIDITY VARIATIONS ON BENDING STRENGTH PROPERTIES OF HYBRID EUCALYPTUS WOOD IN GHANA

The study examines how temperature and relative humidity affect the bending strength properties of hybrid eucalyptus wood from Amantia and Winneba in Ghana. Eucalyptus wood from six trees were tested based on BS 373:1957 under different temperatures and relative humidity levels. The study measured the modulus of elasticity (MOE), modulus of rupture (MOR), and moisture content (MC) of the wood samples. The results showed that MOE and MOR varied significantly across the different conditioning parameters N, T, K and G. MC also influenced the mechanical strength properties of the wood, following the wood-water relation theories. The study concluded that climate and geographical location are important factors to consider when evaluating the mechanical properties of hybrid eucalyptus. This study holds practical implications for optimizing the utilization of eucalyptus wood particularly in the construction and related industries in the three different climatic zones of Ghana

WOOD RESEARCH Volume 67, Number 6, 2022
Manish Ranjan, Anand Nandanwar, and Pradeep Kumar Kushwaha

Comparative study on physical-mechanical properties of plywood produced from eucalyptus grandis and populus deltoids veneers. Short notes

Nine-ply plywood panels were produced from Eucalyptus grandis and Populus deltoids using urea-formaldehyde (UF) and phenol-formaldehyde (PF) adhesives. The physical and mechanical properties, such as moisture content, density, modulus of rupture (MOR) and modulus of elasticity (MOE) of the eucalyptus and poplar boards, were compared in this study. Samples were tested on both, along and across the grain. Higher values of MOR and MOE were observed for eucalyptus as compare to poplar. Density of ply board was observed as 500-560 kg.m-3 in plywood from poplar and 700-720 kg.m-3 in plywood from eucalyptus species. These differences were attributed to the variation in properties of veneer wood species. The effect of veneer wood species on some physical and mechanical properties of plywood was found statistically different.

WOOD RESEARCH Volume 67, Number 2, 2022
THITI WANISHDILOKRATN, SIRILUK SUKJAREON, ITSAREE HOWPINJAI, and LAMTHAI ASANOK

Enhancing leucaena leucocephala wood preservation by steeping it in boron compounds and acetic acid to protect against termites

This study compared steeping Leucaena leucocephala wood with boron compounds and acetic acid to protect it from termites (Coptotermes gestroi). The experiment had a completely randomized design with 10 treatments involving three wood preservatives (acetic acid, boron compounds, and mixtures of both), three treatment lengths (1, 12, and 24 h), and untreated wood, with five replicates of each for a total of 50 conditions. The moisture content of the wood and the wood destroyed by termites were assessed. The L. leucocephala wood treated with boron compounds for 1 h resulted increase in moisture content and no termite damage.

WOOD RESEARCH Volume 61, Number 6, 2016
Xuexia Zhang, Yan Yu, Zehui Jiang, and Hankun Wang

Influence of thickness and moisture content on the mechanical properties of microfibrillated cellulose (MFC) films

Microfibrillated cellulose (MFC) films with a layered structure and controlled thickness were successfully prepared, from bamboo processing resides as the source material, using ultrasonication followed by simple vacuum filtration. The effects of thickness and moisture content on the mechanical properties of the films were then investigated. It was shown that tensile stress and elongation at break were notably affected by the thickness of the MFC film, where the tensile stress and elongation at break of the film increased from 124 to 179 MPa and 0.9 to 5.5 %, respectively, as film thickness increased from 7.4 to 205.4 μm. However, no notable effect of thickness was observed on the Young’s modulus (~10.8 GPa). It was also found that moisture content has a significant impact on the tensile properties of MFC films, in lowering the Young’s modulus from 12 to 2 GPa and tensile stress from 180 to 90 MPa, and increasing the elongation at break from 4.2 to 17.5 %, as moisture content increased from 3 to 60 %. This is due to the effect of water in softening MFC films, resulting in a reduction in strength and increase in flexibility.

WOOD RESEARCH Volume 61, Number 4, 2016
David Bečkovský, Lucie Vacková, Tereza Bečkovská, Jindřich Sobotka, Jan Pěnčík, and Miloš Lavický

Analysis of the diffusional properties of peripheral walls of wooden houses during EMW radiation exposure

The article discusses the changes in diffusion properties of wood and wood-based materials. These changes are caused by excessive moisture content within the materials and the consequent possible attack by wood-destroying pests. Wood-destroying pests in this case are represented by microscopic filamentous fungi (i.e. mould), which slightly changes and deteriorates both, the characteristics of wood and wood-based materials, and the environment humans live in. This paper discusses the theory and application of microwave radiation and the experimental optimization of radiation to sterilize these biotic factors. Furthermore, the article describes the experiments conducted at the Faculty of Civil Engineering, demonstrating the results of sterilization process with regards microscopic fungi that occur in building materials. By analysing the results of the research, the optimum intensity of microwave emitters and necessary lengths of irradiation times were determined.

WOOD RESEARCH Volume 61, Number 3, 2016
Tomasz Rydzkowski and Iwona Michalska-Pożoga

Analysis of intensity of changes in the moisture content of wood chips in the production of wood polymer composites during drying and storage processes

The article presents the results of research on changes in humidity of wood chips intended for the of wood-polymer composites (WPC) manufacture. In the studies were used wood chips of various origin (coniferous and deciduous wood) and the various forms (from dust-meal, through small chips on big chips). Measured moisture content of chips during drying in the dryer and after that, during the natural return to hygroscopic equilibrium with the atmosphere of the storage space. After drying, the samples were stored in open and closed containers.

WOOD RESEARCH Volume 62, Number 5, 2017
Tomáš Kuvik, JOZEF KRILEK, Ján Kováč, Milan Štefánek, and Jiří Dvořák

Impact of the selected factors on the cutting force when using a chainsaw

The paper deals with the calculation and analysis of cutting force and input power when crosscut sawing with a chainsaw. For obtaining and evaluating the results, we have used empirical relationships and the values of appropriate coefficients given by the literature. After the evaluation we have gained the theoretical knowledge of the impact of a tree species and its moisture on cutting force intensity and input power. Tree species have a strong influence on cutting force; the harder the tree species is, the greater cutting force is required. Input cutting power is calculated from the cutting force that is why the impact of a tree species on input power is as big as on cutting force. It has been confirmed that the cutting force and cutting input power are affected by wood moisture content, as well.

WOOD RESEARCH Volume 62, Number 2, 2017
Wei Sun, Xiaokai Mu, Qingchao Sun, and Weiqiang Huang

The impacts analysis of moisture content on mechanical properties of wormwood stem

The disposable chopsticks caused a large amount resources waste of bamboo and wood. Thus, it has a significant resources and environmental benefits using wormwood stem as raw materials to make disposable chopsticks. In this paper, the radial compression and bending performances of wormwood stem were tested with different moisture content, which provide a reference for reasonably design the grinding device of wormwood stem and the feasibility of wormwood stem instead of bamboo chopsticks. The test results show that: the mechanical properties decrease with the increase of moisture content. In the actual grinding process, the moisture content of wormwood stem is controlled about 20%, it can withstand the radial force of 600N and the bending force of 41N, which meet the load requirements of the grinding processing and use. This study provides a theoretical basis for reasonably design grinding device of wormwood stem, producing and storing high quality herbal chopsticks.

WOOD RESEARCH Volume 63, Number 6, 2018
Ergün Güntekin and Hulusi Kaya

Moisture dependent elastic constants of particleboard layers by ultrasound and compression tests

Elastic constants of particleboard layers were investigated using by means of ultrasonic waves and compression tests under different humidity regimes. Three Young’s modulus, three shear modulus and six Poisson ratios were determined. Three longitudinal and six shear wave velocities propagating along the principal axes of anisotropy, and additionally, three quasi-shear wave velocities at 45° angle with respect to the main axes of anisotropy were measured. Compression tests were also conducted in order to measure the accuracy of ultrasonic method. Comparing with calculated values, the predicted Young’s modulus values in the principle directions are acceptable. The shear values calculated using ultrasonic method are higher than those determined from compression tests, particularly in the perpendicular directions. Some of the Poisson’s ratios predicted by ultrasound seem to be extreme. The influence of moisture content on Poisson’s ratios is variable. It can be concluded that ultrasonic method can be used as alternative in determination of elastic modulus for particleboard layers at different moisture conditions. The accuracy of ultrasound for determining the Poisson’s ratios of particleboard layers is questionable.

WOOD RESEARCH Volume 63, Number 5, 2018
Mirko Kariz, Milan Sernek, and Manja Kitek Kuzman

Effect of humidity on 3D-printed specimens from wood-pla filaments

Filaments from a mixture of wood powder and polylactic acid (PLA) polymer were made and used for 3D printing. Different wood ratios were used: 10 %, 20 %, 30 %, 40 %, and 50 %. Specimens were 3D-printed with fused deposition modelling (FDM) printer and conditioned in climates with different levels of relative moisture (RH): 33 %, 65 %, and 87 %. Moisture content (MC), dimensional swelling, and bending properties of printed specimens were measured after conditioning. The results showed that specimens made from filaments with higher wood content had higher moisture content, larger dimensional swelling, and lower modulus of elasticity (MOE).

WOOD RESEARCH Volume 65, Number 1, 2020
Shupin Luo, Li Gao, and Wenjing Guo

Effect of face layer manipulation on the density profile and properties of low density particleboard

Density reduction has gradually become a trend for the particleboard and furniture industries due to increased price and insufficient supply of wood. However, reduced density of the panels by the simple reduction of the wood material comes along with deterioration of the properties. In this study, to achieve sufficient properties (bending properties in particular), the particle moisture content (MC) and geometry in face layers were manipulated to manufacture low density particleboards (500 kg.m-3), with the core layer composed of a mixture of wood particles (92.5 wt %) and expanded polystyrene (7.5 wt %). This strategy was assumed to increase face layer density and generate a more pronounced vertical density profile, which is expected to improve panel properties. The density profile, mechanical properties and dimensional stability of the particleboards were investigated. Results showed that increasing the moisture content of face layer particles from 8% to 16% or using small-sized particle in face layer resulted in a more pronounced density profile, as well as using fiber in face layer. However, the higher density in the face layer was not necessarily related with better mechanical performance. The optimum physic-mechanical properties were obtained with the board of face layer made of 16% MC fiber, which met the requirements for P2 boards used in dry conditions (EN 312).

WOOD RESEARCH Volume 66, Number 3, 2021
Jiangyi Chu, Jinghui Jiang, Chusheng Qi, and Yongdong Zhou

Study on concentrations of acids and alcohols emitted by pinus radiata during high-temperature drying

The purpose of this paper is to investigate the influence of kiln temperature, relative humidity and wood moisture content on the content of acid and alcohol released in the drying process of high temperature kiln by studying the radiated pine sawn timber of 40mm thickness. The drying temperature was between 101°C and 115°C, the relative humidity in the drying kiln was reduced from 86.1% to 39.6%, the moisture content of the lumber was reduced from 106.16% to 11.98%, and gas extraction was executed nine times with an extraction speed of 1.0 L•min-1 and a sampling time of 30 min. The concentrations of acids and alcohols were analyzed by HPLC. The results showed that the concentrations of formic acid, acetic acid, and methanol emitted in the kiln during drying were 215.6-748.2, 4148.8-16803.2, and 6381.9-15648.9 mg•m-3, respectively, and these concentrations were significantly higher than the relevant standards. The concentrations of the emitted formic acid and acetic acid were proportional to the drying temperature, the concentrations of the emitted formic acid and acetic acid were inversely proportional to the relative humidity in the kiln and the moisture content of the lumber. The concentration of the emitted methanol was independent of the drying temperature, relative humidity in the kiln, and moisture content of the lumber. It is therefore suggested that formic acid, acetic acid, and methanol be separately recovered during the high-temperature drying of Pinus radiata lumber.

WOOD RESEARCH Volume 64, Number 3, 2019
Roman Fojtík

Moisture content analysis of wooden bridges

The article deals with assessing the impact of moisture content conditions in wood mass of the wood bridges constructions on their lifespan in Central Europe. Wood moisture content as one of main factors influencing the wooden elements mechanical properties was studied on seventeen wooden bridge constructions. The dependence of temperature and relative humidity on material moisture content was observed in summer season and also in winter season. The lifespan of historical and modern wood structures was discussed as well.