WOOD RESEARCH Volume 69, Number 1, 2024
HARUNA SEIDU, MARWA BROUGUI, NOOR ROZIANA ABDUL RAHIM, and RÓBERT NÉMETH

EVALUATION OF DYNAMIC AND STATIC MODULI OF ELASTICITY OF HYBRID EUCALYPTUS WOOD FROM DIFFERENT LOCATIONS IN GHANA

This study explores the mechanical properties of hybrid eucalyptus wood, with a focus on dynamic and static moduli of elasticity (MOE), which is crucial for understanding the stiffness behaviour of wood. The research employs acoustic and static measurements on samples prepared from six trees sourced from Winneba and Amantia in Ghana. The results reveal significant variations in static and dynamic MOE, with higher static MOE observed in both Amantia and Winneba samples. However, Winneba and Amantia samples at the tree level were found to be insignificant statistically. The densities of the samples from the two locations, Winneba and Amantia, were found to be significantly different. Correlation studies revealed strong relationships between wood density and static MOE, as well as static and dynamic MOE, providing valuable insights into the comprehensive characterization of the eucalyptus globulus species grown in Ghana

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 68, Number 3, 2023
HARUNA SEIDU, RÓBERT NÉMETH, Francis Wilson Owusu, James Korang, Appiah-Kubi Emmanuel, James Kudjo Govina, Fath Alrhman A.A Younis, and Safia Ibrahim

Mechanical Properties of PF and MUF Bonded Juvenile Hybrid Eucalyptus Plywoods Produced in Ghana

To obtain the mechanical properties of plywood produced from six yearold hybrid Eucalyptus in Ghana was the objective of this research. The samples for the experiment were prepared and tested according to GS EN 326-1, GS EN 310, GS EN 314-1, and GS EN 314 -2. The data obtained were analysed using the factorial ANOVA analysis. The mean results obtained for the various treatments were MOE (6520 – 7638 N/mm2), MOR (53.29 – 60.56 N/mm2, shear strength (2.47 – 5.51 N/mm2), failure (72 -90%) and density (725 – 748 kg/m3). The orientation of the surface veneer caused variations among treatments whiles the adhesives PF and MUF largely did not cause any variations among treatments. This study has proven that it is possible to produce sufficiently strong and resistant plywood from the juvenile wood of eucalyptus.

WOOD RESEARCH Volume 62, Number 2, 2017
Simon Eichhorn, Sebastian Erfurt, Tamás Hofmann, Stefan Seegmüller, RÓBERT NÉMETH, and František Hapla

Determination of the phenolic extractive content in sweet chestnut (Castanea sativa Mill.) wood

The reason for the excellent natural durability of Sweet chestnut wood can be primarily explained with the extractives incrusted in the wood cell wall. These compounds basically involve tannins, which protect the heartwood against wood decaying microorganisms. Research carried out on the wood of ring-porous broadleaved species revealed that there is a significant radial variation in the concentration of phenolic extractives. The present research focused on the radial distribution of total phenol and ellagitannin content in the heartwood of Sweet chestnut stems, originating from different forest stands. It was also investigated if there was a significant correlation between water supply of the treesand the distribution of phenolic compounds. Total phenol and ellagitannin contents generally increased from juvenile wood towards the sapwood/heartwood boundary, lowest values were determined in sapwood tissues. Respecting water supply it was established that the heartwood of trees growing in a dryer foreststand, contained significantly higher phenolic extractives compared to trees in well water-supplied, fresh forest sites. However, ellagitannin contents didn’t significantly differ between sites. The utilization of the wood of naturally durable European species, including Sweet chestnut, will gain in importance in the future basing on the growing common ecological awareness of the population.

WOOD RESEARCH Volume 63, Number 3, 2018
Mátyás Báder and RÓBERT NÉMETH

The effect of the relaxation time on the mechanical properties of longitudinally compressed wood

Longitudinal compression makes natural wood easier to bend. The relaxation after compression results in much improved bending properties. During a bending test, the maximum deflection increases with the relaxation time, while the needed force to reach the same deflection decreases, similarly to the modulus of elasticity (MoE). The modulus of rupture (MoR) of the compressed wood does not change considerably compared to the untreated wood, except at the long-time relaxed samples. The ideal relaxation time is 1 minute. After that the change of the important properties slows down. Of course with special demands, the relaxation time can be also very long. In this case the process leads to a wood sample with pronounced flexible properties. Samples were left to rest between normal circumstances for 1 day, but this resting period did not have a significant effect on its mechanical properties.