WOOD RESEARCH Volume 69, Number 4, 2024
HARUNA SEIDU, RÓBERT NÉMETH, and FRANCIS WILSON OWUSU

MECHANICAL STRENGTH CHARACTERIZATION OF THREE LESSER-UTILISED TIMBER SPECIES IN GHANA

This study investigates the mechanical properties of three lesser-utilized timber species in Ghana: Blighia sapida, Gilbertiodendronlimba, and Lanneawelwitschii. Despite their potential, these species are underexplored compared to widely used commercial timbers. Six trees, two from each species, were tested for properties such as modulus of elasticity (MOE), modulus of rupture (MOR), compressive strength, shear strength, hardness, and density. Results indicate that Blighia sapida has superior mechanical properties, placing it in the D50 strength class, suitable for high-resistance structural applications. Gilbertiodendronlimba and Lanneawelwitschii are categorized under the D40 strength class, appropriate for moderate load-bearing uses. This research demonstrates that lesser-utilized species can serve as viable alternatives to traditional timbers, potentially reducing pressure on overexploited species. By promoting their use, the study supports sustainable forestry practices and contributes to a more diversified and resilient timber industry in Ghana

WOOD RESEARCH Volume 69, Number 4, 2024
MARIJA TODOROVIĆ, IVAN GLIŠOVIĆ, and NAĐA SIMOVIĆ

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF CLT PANELS WITH DIFFERENT ORIENTATIONS OF TRANSVERSE LAYERS

This paper presents an experimental and numerical investigation of two configurations of panels made of locally produced cross-laminated timber (CLT) with different orientations of laminations (boards) within transverse layers – conventional and modified orientation. Modified orientation refers to laminations of transverse layers positioned at an angle of ±45° in relation to longitudinal layers. The expected advantages of modified CLT are improved mechanical performance, more efficient use of resources considering material properties, reduction in variability of characteristics within the panels and increase in shear resistance. In addition to experimental testing, numerical analysis based on finite element method was performed and successfully validated in order to serve as a more efficient tool for CLT panel investigation and optimization

WOOD RESEARCH Volume 69, Number 4, 2024
SINTA AMANAH, RESA MARTHA, EFRIDA BASRI, MAHDI MUBAROK, ISTIE SEKARTINING RAHAYU, IRSAN ALIPRAJA, WAYAN DARMAWAN, PHILLIPPE GÉRARDIN, LUKAS EMMERICH, HOLGER MILITZ, and UMMI HANI ABDULLAH

THE EFFECT OF WEATHERING ON SURFACE CHARACTERISTICS OF CHEMICALLY MODIFIED SCOTS PINE (PINUS SYLVESTRIS) WOOD

Scots pine (Pinus sylvestris L.) sapwood of 200 × 20 × 80 mm3 (L×R×T) was treated with both cell wall filling and lumen filling chemical agents (low-molecular phenol-formaldehyde, bio-oil, N-methylol/N-methyl compounds, sorbitol-citric acid, polysiloxane), which were fixed inside the wooden structure during heat-curing processes. The present study investigated the impact of the appointed chemical modifications on the surface characteristics of wood, which was addressed by measurements of the surface roughness (Ra), surface free energy (SFE), contact angles, wettability and its bonding quality. Independent of the chemical agents applied, Ra decreased as result of the chemical treatments, while SFE experienced a reduction. The Ra and SFE of both untreated and modified pine specimens increased after weathering processes. The weathering was appointed to cause a decrease in the equilibrium contact angle (θe) and an increase in the constant contact angle change rate (K-value). Increasing K-values after weathering for both untreated and modified pine specimens indicated their better wettability. Increasing wettability after weathering led to better adherence of acrylic paints on the surface of the Scots pine wood. In summary, the chemical modifications decreased the Ra and SFE of the pine sapwood, which may as a consequence affect the wettability and bonding quality of wood during outdoor exposure

WOOD RESEARCH Volume 69, Number 4, 2024
CHUMIN CHEN, MING LI, SAIYIN FANG, and BO ZHANG

ANISOTROPIC VELOCITY MODEL AND ENERGY ATTENUATION CHARACTERISTICS OF ACOUSTIC EMISSION SIGNALS IN FINGER-JOINTED TIMBER AND SAWN TIMBER

Although anisotropic propagation behavior of acoustic emission (AE) in the sawn timber (ST) has been revealed, that in finger-jointed timber (FJT) is still less known.Therefore, a series of velocity and energy models of AE signalswere built as it propagates along different directions on the surface and inside of specimens (ST and FJT). At first, using polar coordinate system, velocity model in 36 directions was built in FJT, which was compared to ST.Furthermore, a continuous sine wave with a frequency of 165 kHz was selected as AE source to explore the energy attenuation law in FJT and ST respectively.The results showed that there are significant differences in velocity models between FJT and ST.The wavefront in STwas regular elliptical, while that in FJT has a clear depression in perpendicular to grain direction.This feature becomes more obvious with the increase of distance when AE signal propagates inside the FJT.Inside the FJT,energy magnitude in STwas 3.00-7.37 times of that in FJT

WOOD RESEARCH Volume 69, Number 4, 2024
JINGE XIE, HONGHAI LIU, YU XIE, and XIAOKAI ZHANG

INFLUENCE OF TEMPERATURE AND PRESSURE ON SUPERCRITICAL CO2 DEWATERING OF BAMBOO STRIPS

In this study, therepressure (15, 22.5, 30 MPa) and two temperature (45, 60°C) of ScCO2dewatering were tested on Moso bamboo (Phyllostachys edulis) strips. The aim was to research the effects of these conditions on the dewatering rate, moisture distribution, and shrinkage of bamboo. The results showed that: 1)The first cycle discharges the most water of all drying conditions. The most effective dewatering time consisted of a 15 min depressurization period and a 5 min discharge period. 2)The ScCO2 dewatering rate of bamboo strips decreased with decreasing MC, with a maximum decrease of 78%.The maximum and minimum dewatering rates were 37.04%/h and 4.41%/h, respectively. The dewatering rate was synergistically affected by temperature and pressure, which increased significantly with pressure at 45°C, but was minimized at 60°C at 22.5 MPa. 3)After dewatering, the moisture distribution in the bamboo strips shows a trend of higher moisture content(MC) in the middle and lower MC on both sides in the tangential and radial directions. 4)Most of the bamboo strips produced shrinkage after the 1st cycle of dewatering, and the overall shrinkage in the tangential direction was greater than that in the radial direction. The maximum tangential and radial shrinkage rations are 3.06% (22.5 MPa/45°C) and 0.94% (15 MPa/60°C), respectively.

WOOD RESEARCH Volume 69, Number 4, 2024
DOAN VAN DUONG1, MASUMI HASEGAWA, MANH TUONG VU, and VAN HUNG HOANG

RADIAL AND AMONGCLONAL VARIATIONS OF TRANSVERSE SHRINKAGE AND BASIC DENSITY IN 5-YEAR-OLDACACIA AURICULIFORMIS CLONES PLANTED IN VIETNAM

This study investigatedtransverse shrinkages and wood density for Acacia auriculiformis trees from six clones planted in north-central Vietnam. Radial and among-clonal variations of partial and total shrinkages in tangential (respective to Tn and T) and radial (respective to Rn and R) directions, partial and total coefficient of anisotropy (respective to Tn/Rn and T/R), and basic density (BD) were examined. There were significant differences among clones for Rn and R, but no significant differences were found among clones for Tn and T. The lowest average Rn and R were detected in clones Clt18 and Clt26, suggesting that these clones might be more appropriate for breeding programs focused on improving shrinkage traits for sawn timber production. BD is not a good indicator for predicting transverse shrinkages. In contrasts, stress wave velocity measured in standing trees has the potential to be used as a non-destructive method for predicting the transverse shrinkage of A. auriculiformis planted in Vietnam

WOOD RESEARCH Volume 69, Number 4, 2024
LEIF PORTAL, ROGER CHAMBI, JÚLIA GIL, GABRIEL PEREIRA, and MARIO TOMAZELLO

MAPPING WOOD DENSITY VARIATION USING QGIS: AN INNOVATIVE APPROACH FOR CHARACTERIZATION OF OCHROMA PYRAMIDALE, ACACIA MANGIUM, EUCALYPTUS GRANDIS, AND PINUS SP.

This study explores the innovative application of QGIS for mapping radial wood density variation across the entire cross-section of selected native and non-native forest species, aiming to enhance wood characterization. Using samples from Ochroma pyramidale, Acacia mangium, Eucalyptus grandis, and Pinus sp., we applied X-ray densitometry to obtain high-resolution images, which were then analyzed with QGIS to create detailed density maps. These maps provided a clear visualization of radial density variation, offering insights into the internal structure of the wood. The integration of QGIS with X-ray densitometry proved to be an effective tool for assessing wood density variation, supporting more precise and sustainable forest management practices