Articles

WOOD RESEARCH Volume 70, Number 3, 2025
Holta Çota, ENTELA LATO, DOKLEA QUKU, HEKTOR THOMA, and ERALD KOLA

The Effect of Heat Treatment on Compression Strength of Silver fir (Abies alba Mill.) and Ash Wood (Fraxinus angustifolia Vahl.). Short notes

This study investigates the effects of thermal modification on the compressive strength parallel to the grain of ash (Fraxinus angustifoglia Vahl.) and fir (Abies alba Mill.) wood. Specimens were thermally treated at 130°C, 180°C, and 220°C for durations of 2 and 8 h under atmospheric conditions. Mass loss increased with both temperature and time, with fir exhibiting greater loss than ash, up to 20.3% and 15.7%, respectively, at 220°C for 8 h. Compressive strength was influenced significantly by treatment intensity. Fir showed minor improvements at lower temperatures but experienced a reduction of up to 23.0% at the highest treatment. In contrast, ash displayed enhanced strength at 180°C (up to +15.1 %) and retained better mechanical performance at 220°C, with a maximum reduction of 11.3%. These findings demonstrate that heat treatment can both enhance and deteriorate compressive strength depending on the treatment severity, emphasizing the need to optimize thermal parameters for maintaining structural performance in wood applications.

WOOD RESEARCH Volume 70, Number 3, 2025
HARUNA SEIDU, LÁSZLÓ BEJÓ, and RÓBERT NÉMETH

COMPARATIVE ANALYSIS OF MOE AND MOR OF PF AND MUF-BONDED EUCALYPTUS PLYWOOD OF VARYING THICKNESS. Short notes

This study assesses the mechanical characteristics of eucalyptus plywood produced in Ghana, particularly focusing on how panel thickness (9–21 mm) and adhesive type (phenol formaldehyde (PF), and melamine urea formaldehyde (MUF) influence the modulus of elasticity (MOE) and modulus of rupture (MOR) of the panels. The panels were tested according to EN 310: 1993. The results indicate that mechanical strength and thickness are inversely correlated, with thinner panels exhibiting superior performance. MOR decreased from 59.85 N/mm² to 39.36 N/mm² for PF-bonded plywood, while longitudinal MOE declined from 7096 N/mm² (9 mm) to 4627 N/mm² (21 mm). Although their values were lower (from 6093 N/mm² to 4155 N/mm²), the MUF-bonded panels demonstrated comparable trends. Significant differences based on orientation were confirmed by ANOVA analysis (p < 0.01), showing that longitudinal samples significantly recorded higher values than transverse ones, particularly in thinner panels. Thicker panels exhibited less anisotropy due to stress homogenization, but PF adhesives provided greater mechanical stability compared to MUF.

WOOD RESEARCH Volume 70, Number 3, 2025
EUN-SUK JANG, GYEONG-TAEK LIM, and HEE-JUN PARK

IMPREGNATION EFFICIENCY OF FLAME RETARDANTS IN HINOKI CYPRESS (CHAMAECYPARIS OBTUSA) PLYWOOD USING THE VACUUM-PRESSURE METHOD. Short notes

This study aimed to investigate the effectiveness of vacuum-pressure impregnation for the flame-retardant treatment of hinoki cypress (Chamaecyparis obtusa) plywood. The effect of impregnation duration (50–75 min) on the solid content of flame-retardant impregnation (SCFI) was analyzed. The SCFI significantly increased with rising impregnation time, as demonstrated by analysis of variance and regression analysis. In addition, the outer regions of the plywood exhibited higher impregnation efficiency than the inner regions owing to directional permeability. These results emphasize the importance of impregnation time and fiber orientation in optimizing the flame-retardant treatment processes.

WOOD RESEARCH Volume 70, Number 3, 2025
IRYNA LYTVYN, NATALIYA BEKHTA, IRYNA KUSNIAK, PAVLO BEKHTA, and JÁN SEDLIAČIK

Properties of Particleboards with Partial Replacement of MUF Resin by Sodium and Magnesium Lignosulfonates

The objective of this study was to evaluate the feasibility of partially replacing melamine-urea-formaldehyde (MUF) resin with lignosulfonates and to assess the effects on the physical and mechanical properties of the boards. Particleboards were produced using MUF resin, with partial substitution by either sodium lignosulfonate (NaLS) or magnesium lignosulfonate (MgLS) at levels of 10%, 20%, and 30% by weight. Control boards were also manufactured using 100% MUF resin for comparison. The results demonstrated that both, the type and proportion of lignosulfonate, significantly influenced the physical and mechanical characteristics of the boards. Specifically, the lignosulfonate content had a notable negative effect on the internal bond (IB) strength, bending strength (MOR), and thickness swelling (TS). In contrast, the type of lignosulfonate significantly affected only the IB strength. Boards containing 10% NaLS exhibited comparable properties to those of the control group. Additionally, boards incorporating NaLS generally outperformed those containing MgLS, although the differences were not statistically significant. Particleboards incorporating with 10% or 20% NaLS or MgLS, although exhibiting lower IB strength, MOR and modulus of elasticity (MOE) than the control boards, met the performance criteria for type P2 boards, intended for interior applications (including furniture) in dry conditions, as specified by the EN 312.

WOOD RESEARCH Volume 70, Number 3, 2025
MELİS ÇERÇİOĞLU, MUHAMMED ALİ AYDIN, YASİN KARAŞİN, BURAK BAHAR, and DERYA EŞEN

Effects of mulching on selected properties of soil and young stone pine (Pinus pinea L.) seedlings under semi-arid conditions

Evaporation is a primary source of soil moisture loss, and mulching can effectively reduce this loss, thereby conserving soil moisture. This study examined the effects of wood-materials mulching with various particle sizes and application depths (5-cm thick coarse sawdust, 5-cm thick wood chips, and 10-cm thick wood chips) on some soil properties, including moisture, bulk density (BD), pH, electrical conductivity (EC), organic matter (OM), and CaCO₃, as well as on stone pine (Pinus pinea L.) seedling root collar diameter (RCD), height, sturdiness index (SI), and survival rates. One-year-old containerized stone pine seedlings, a drought-tolerant and economically valuable native conifer species, were planted with a spacing of 3 x 3 m in Aliaga, Izmir, Türkiye. Ten months after treatment (July 2024), no significant differences in soil bulk density and moisture were observed among treatments. The 10-cm-thick wood chips treatment showed significantly greater organic matter content compared to both the control and the 5-cm-thick coarse sawdust treatments. Although large numerical differences were seen in mean pine survival rate and height growth, these differences were not statistically significant, likely due to high data variability. The 10-cm-thick wood chips and 5-cm-thick coarse sawdust treatments demonstrated relatively higher seedling survival rates, while the control treatment showed the lowest seedling survival. However, the control seedlings exhibited significantly greater root RCD than mulch treatments, with the 5-cm-thick coarse sawdust treatment ranking second in promoting seedling RCD. Early results did not indicate enhanced pine survival and growth due to mulching. However, future data collection is recommended to provide further insights.

WOOD RESEARCH Volume 70, Number 3, 2025
ADÉLA VALENTOVÁ, TEREZA MAJSTRÍKOVÁ, and JANA DAŇKOVÁ

MINERALISATION TREATMENT OF WOOD MATRIX BY HYDRATED LIME

This article concerns the application of lime treatment on wood surfaces. This interaction led to alkaline hydrolysis of the polysaccharide component,which isdirectly linked to physical and mechanical parameters.Whereas the composites utilise the advantageous ecological parameters of the lime binder and wood particle filler, it is necessary to describe this utilisation. Thermal analysis indicated that the transformation of hydrate to carbonate occurs relatively quickly in a thin layer, without causing significant changes in the structure of the wood. This is also confirmed by optical microscopy images. Tests onsmall, defect-free specimens were also conducted to assess the impact on compressive strength parallel to the grain.

WOOD RESEARCH Volume 70, Number 3, 2025
DONATA KRUTUL, ANDRZEJ ANTCZAK, MICHAŁ DROŻDŻEK, MONIKA MARCHWICKA, ANDRZEJ RADOMSKI, Teresa Kłosińska, and JANUSZ ZAWADZKI

Influence of urban agglomeration environment pollution on the concentration of some non-metals in the trunk of Acer platanoides L.

The influence of environmental pollution on the concentration of some non-metals in wood and bark from trunks of Acer platanoides L. obtained from the crossroads of Platynowa and Towarowa Streets and KrakowskiePrzedmieście Street in Warsaw was observed. Samples were collected from approx. 30-year-old and 40 year-old trees from the butt-end and the mid-height of the trunk part as well as from the top part. On the cross-section of the butt-end and the mid-height, the following sections were distinguished: outer, middle and pith adjacent middle wood and of the butt-end part bark was obtained. The discs from the upper part of the trunks were not divided into sections due to their small diameter. The concentrations of chlorine (Cl-), nitrate (NO3-), sulphate (SO4-) and hydro phosphate (HPO42-) anions were determined using HPLC with a conductometric detector. The content of nitrogen (N) was examined with the Kjeldahl method. The influence of the environmental pollution caused by urban agglomeration on the nitrogen content was denoted. Additionally, chlorine anions concentrations in wood and bark were increased.

WOOD RESEARCH Volume 70, Number 3, 2025
ERZHUANG ZHAI, SAIYIN FANG, MING LI, TINGTING DENG, BOWEN ZHANG, JIAXIN GUO, KEFEI CHEN, and KUN DU

Research on clustering identification of acoustic emission events in the process of wood crack propagation using PCA

This study presents a methodology for feature extraction and identification of acoustic emission (AE) events during wood crack propagation utilizing Principal component analysis (PCA) and enhanced K-means clustering algorithm. Experimental setups included double cantilever beam (DCB) for mode I crack propagation analysis and three-point bending test for mixed-mode crack propagation assessment. Various AE parameters, such as amplitude, duration, absolute mean value, peak frequency, and frequency centroid, were computed. PCA applied for dimensionality reduction to extract principal components and eliminate redundant information. The optimal number of clusters was determined using a combination of the elbow method and the Davies-Bouldin index to classify damage modes. Results indicate that the principal components contribute to 88.5% and 92% of the variance in the two tests, respectively, yielding three distinct types of AE events in both crack propagation scenarios. Specifically, high-frequency, low-amplitude signals correspond to microcrack initiation; low-frequency, low-amplitude signals signify interface delamination; and high-amplitude, long-duration events indicate mode I opening macroscopic damage (high frequency) and mixed-mode macroscopic failure (low frequency).

WOOD RESEARCH Volume 70, Number 3, 2025
LEIF PORTAL and MARIO TOMAZELLO

VARIABILITY OF THE APPARENT DENSITY IN THE WOOD OF SWIETENIA MACROPHYLLA AND CEDRELA ODORATA IN THE AMAZON REGION OF PERU

This study examines the radial variability of apparent wood density in two tropical commercial species, Swietenia macrophylla (mahogany) and Cedrela odorata (cedar), in the Peruvian Amazon. The hypothesis states that both species will present different radial variation patterns in wood density, with C. odorata showing greater heterogeneity due to its older age and the presence of mineral inclusions. Advanced methods, including X-ray microdensitometry and visual analysis with QGIS, were used to obtain radial density profiles. Results showed that C. odorata exhibited higher variability and a wider density range than S. macrophylla, mainly attributed to age and mineral inclusions affecting density measurements. These differences are important for the timber industry, influencing mechanical properties and material selection. The findings emphasize the significance of density variability for sustainable management and improving timber quality in the Amazon region.

WOOD RESEARCH Volume 70, Number 3, 2025
NUR DZAKIRA SAHBANI, ANDI DETTI YUNIANTI, SUHASMAN S, Kidung Tirtayasa Putra Pangestu, GUSTAN PARI, and LISNA DEVIYANTI

EFECTIVENESS OF SAPPAN WOOD DYE MICROPARTICLES IN THE DYEING OF CANDLENUT AND GMELINA WOOD WITH ALUM AND SODA ASH MORDANTING PRETREATMENT

The aesthetic appearance of wood, especially for handicrafts, is greatly influenced by color. Dyeing is an important method to improve the aesthetics of wood. This research focuses on the effectiveness of wood staining using natural dyes from sappan wood, which has the color-giving compound brazilin. However, natural colorants are often less effective due to their low affinity to wood. Therefore, this study aimed to determine the effectiveness of micro-particles of sappan wood natural dye on candlenut wood and gmelina wood. The pretreatment given during the dyeing process is mordanting using alum and soda ash to improve color absorption and durability. The results showed that mordanting pretreatment with a combination of alum and soda ash (5 g/l : 5 g/l) provided optimal dye penetration depth in both types of wood. FTIR analysis confirmed the interaction between the colorants and the wood components. Candlenut wood showed deeper dye penetration than gmelina wood, which is thought to be due to differences in the anatomical structure of the wood.

WOOD RESEARCH Volume 70, Number 2, 2025
JING LANG, JIANJUN ZHOU, ZHENZHONG TANG, and JIANHUI ZHANG

Recent Advances in Strengthening and Reinforcing Technologies for Paper Documents: A Comprehensive Review

The reinforcement and strengthening of paper documents have garnered widespread global attention. Delaying the degradation process of paper documents, enhancing their restoration and protection measures hold profound historical and cultural significance for the inheritance of cultural heritage. This study provides a comprehensive review of international advancements in the primary types of strengthening and reinforcement materials as well as the corresponding reaction mechanisms for paper documents. Furthermore, it offers a forward-looking perspective on emerging research trends in the field of reinforcement and preservation for paper documents

WOOD RESEARCH Volume 70, Number 2, 2025
LI XUELI, ZHANG YAOYI, ZHU LIZHI, FU ZHIQIANG, SONG SHUAIHAO, and WU JING

POLYETHYLENE GLYCOL/WOOD FLOUR PHASE CHANGE MATERIALS INCORPORATED INTO BIODEGRADABLE WOOD PLASTIC COMPOSITES FOR THERMAL ENERGY STORAGE

To enhance the mechanical and thermal stability of wood-plastic composite phase change materials (WPC PCMs), polyethylene glycol (PEG)/wood flour (WF) PCMs were prepared via solution impregnation. These were added to cellulose, polycaprolactone (PCL), and polylactic acid (PLA)-blended degradable plastics and then compression-molded into WPC PCMs. The materials were characterized using mechanical and thermal tests (SEM, FT-IR, DSC, TG). Research shows that capillary action enables WF to encapsulate PEG, reducing post-phase transition leakage and facilitating heat storage. As PEG content changes, phase change enthalpy and temperature first decrease, then increase, and finally stabilize, with a high latent heat of 33.97 J/g. WPC PCMs exhibit good thermal stability with increasing PEG. When the addition amount of PEG was 30%, compared with the initial decomposition temperature and the maximum decomposition temperature of the material without PEG addition, they increased by 24.4°C and 26.9°C respectively.PEG increases the thermal conductivity of WPC PCMs within a certain range, but the increase is limited. Due to its simple preparation, WPC PCMs have broad application prospects in solar and biomass energy storage

WOOD RESEARCH Volume 70, Number 2, 2025
YOSAFAT AJI PRANATA and BAMBANG SURYOATMONO

Behavior of Bolted Beam-to-Column Timber Connections using Double Steel Plates

This study aims to investigate the behavior of bolted beam-to-column timber connections with double steel plates. The behavior of the connections, as their strength, initial rotational stiffness, energy dissipation, and ductility ratio, were studied. Test specimens made of red meranti species (Shorea spp.) connected by 5-mm thick steel plates on both sides, and bolted joints of diameters 10 mm and 12 mm were used. Experimental tests of the connections conform to the EN 26891: 1991. The failure mode is splitting of the bolt row path in the column for all connections with the same numbers of bolts in the beam and the column, and splitting of the bolt row path in the beam for all connections with fewer numbers of bolts in the beam than those in the column. Moreover, the results show that the use of combined bolts and double steel plates has an impact in increasing both the ductility ratio and the energy dissipation of the connections

WOOD RESEARCH Volume 70, Number 2, 2025
ZHIYING TIAN, SAIYIN FANG, MING LI, TINGTING DENG, ERZHUANG ZHAI, CHUMIN CHEN, and YONGCHUAN WU

THE ANISOTROPIC VELOCITY MODEL OF INTERNAL ACOUSTIC EMISSION SIGNALS IN ZELKOVA WOOD AND THE INFLUENCE OF HOLES ON THEIR PROPAGATION PROCESS

In this article, an acoustic emission (AE) source was generated through pencil-lead break (PLB). On Zelkova schneideriana specimens featuring central through-holes with diameters ranging from 8 to 16 mm, the time-difference-of-arrival (TDOA) in combination with the least squares fitting approach was utilized to establish an anisotropic model of the AE wave velocity within the wood as it varies with the detection angle. Then, a pulse signal was generated through a signal generator to analyze the influence of the holes on the peak values of AE signals at different angles. The results indicate that when the propagation angle is less than 80°, the AE wave velocity rises rapidly with the increase of the angle and eventually approximates the longitudinal wave velocity along the grain. The AE signal peak emerged in the direction approximately 30° for the specimen without holes. In the presence of holes, as the hole diameter increases, the variation trend of AE peak amplitudes within an angular range of -18° to +18° relative to the hole center becomes progressively smoother, with a concurrent reduction in their mean value. This distinct characteristic can serve as a robust indicator for identifying internal hole defects in wood

WOOD RESEARCH Volume 70, Number 2, 2025
YONGCHUAN WU, SAIYIN FANG, MING LI, TINGTING DENG, CHUMIN CHEN, and ZHIYING TIAN

ANISOTROPIC PROPAGATION CHARACTERISTICS OF ACOUSTIC EMISSION SIGNALS IN WOOD

This study investigates the propagation characteristics of acoustic emission (AE) signals in Zelkova schneideriana and Pinus sylvestris var. mongolic along different directions, with a focus on amplitude and frequency variations. Sinusoidal signals ranging from 10 to 400 kHz, along with pulsed signals of 1 μs width and 1 s period, were generated using an arbitrary waveform generator to simulate the AE source. Experiments were conducted on 80 mm cubic wood specimens, with the AE source and sensors positioned at the geometric centers of each surface. AE signals were recorded at a sampling rate of 2 MHz. The results indicate that, at the same frequency, the Zelkova schneideriana exhibits higher signal amplitude and energy than the Pinus sylvestris var. mongolic. Frequency response analysis further reveals that wood enhances the propagation of signals below 75 kHz, while significantly attenuating signals above 200 kHz in the transverse direction

WOOD RESEARCH Volume 70, Number 2, 2025
JÁN SEDLIAČIK, PAVLO BEKHTA, IGOR NOVÁK, ANGELA KLEINOVÁ, MATEJ MIČUŠÍK, JÁN MATYAŠOVSKÝ, and PETER JURKOVIČ

SURFACE PROPERTIES OF HYDRO-THERMALLY MODIFIED BEECH WOOD AFTER RADIO-FREQUENCY DISCHARGE PLASMA TREATMENT

Heat treatment is widely used to improve the properties of wood, in particular its color. However, this treatment causes changes in the surface properties of wood, the surface becomes hydrophobic, which can cause serious problems when gluing or coating. In this study, the radio-frequency discharge (RFD) plasma was used to increase the hydrophilicity of the steam-modified beech (Fagus sylvatica L.) wood due to the formation of various polar groups (e.g., hydroxyl, carbonyl, carboxyl, etc.). The increased surface polarity improves the wettability and hydrophilicity due to oxidation reactions. Tensile shear strength properties of lap joints were processed according to EN 205. Plasma-treated samples showed higher strength when compared to plasma-non treated samples after the D4 test according to EN 204

WOOD RESEARCH Volume 70, Number 2, 2025
ÇAĞATAY ERSİN and MEHMET GÜNEŞ

MODELLING OF BIRCH WOOD (BETULA SPP.) SURFACE ROUGHNESS DEPENDING ON LASER PROCESSING PARAMETERS WITH RESPONSE SURFACE METHODOLOGY

In this study, the effect of laser engraving parameters on birch wood surface roughness was investigated with response surface methodology (RSM) and a mathematical model was developed. Laser power (W%), speed (mm/min) and space (mm) were selected as independent variables. Ra, Rq and Rz surface roughness indices were measured as response variables. In the study, 20 experimental conditions were conducted with 3-factor and 3-level experimental designs using central composite design (CCD). Laser engraving power and space were determined as the most effective factors on surface roughness. Regression models were developed for each surface roughness index and the measurements were estimated. In the model created for Ra surface roughness, R² = 97.0% and the average error was found to be 4.9%, for Rq, R² = 96.8% and the average error was found to be 4.5%, for Rz, R² = 96.6% and the average error was found to be 4.0%. It is understood that the surface roughness values will be predicted with high accuracy with the created model

WOOD RESEARCH Volume 70, Number 2, 2025
ZIXING MA, MENG ZHOU, YANGYI WANG, QIYUE WANG, HELAN XU, and XIULIANG HOU

PREPARATION OF ECO-FRIENDLY COMPOSITE PAPER WITH GINKGO LEAF AND BIO-BASED FIBERS

Ginkgo leaf was treated with deep eutectic solvents and then mixed with bio-based fibers, willow catkins or kapok fibers as reinforcing materials to prepare ginkgo leaf composite paper. The effects of the papermaking process conditions and the proportion of ginkgo leaf on the properties of the composite paper were studied. The results showed that the properties of the composite paper were better when the proportion of ginkgo leaf was within the range of 70-90%, with a smooth surface, high strength, and flexibility, which can meet the needs of daily packaging. The higher the proportion of ginkgo leaf, the better the anti-ultraviolet property and the higher the strength. When the proportion of willow catkins or kapok fibers was higher, the water resistance and flexibility were better. Among them, when the proportion of ginkgo leaf was 90%, the ultraviolet protection factor (UPF) could reach 128, showing excellent anti-ultraviolet property. When the proportion of ginkgo leaf was 70%, the water contact angle to composite paper was 144.2°, indicating water resistance

WOOD RESEARCH Volume 70, Number 2, 2025
GANIS LUKMANDARU, MUHAMMAD AKBAR FAQIH, and SIGIT SUNARTA

PULPING AND PAPERMAKING POTENTIAL OF ACACIA AULACOCARPA BENTH WOOD IN INDONESIA

In this study, samples from 27-year-old Acacia aulacocarpa grown on a plantation were examined to determine suitable kraft pulping conditions and properties for paper production. The results showed that A. aulacocarpa had a high basic density of 0.65 g/cm3 and a short fiber length of 0.84 mm. The derived values for Runkel, slenderness, and flexibility ratios were 1.02, 53.01, and 0.48, respectively. Five different active alkali concentrations ranging from 14% to 22%, with intervals of 2% were applied for kraft cooking. The percentages of reject, kappa number, and residual active alkali of black liquor were negatively related to the charge applied in pulping runs. Pulping with 18% active alkali content obtained a screened yield of 51.4% at a kappa number of 34.1. The 20% active alkali cook had the highest mechanical properties of the handsheets. The burst and tear indices met the Indonesian National Standard for leaf (hardwood) bleached kraft

WOOD RESEARCH Volume 70, Number 2, 2025
TSHWAFO ELIAS MOTAUNG, ELLA CEBISA LINGANISO-DZIIKE, ZIKHONA TETANA, LEHLOHONOLO FORTUNE KOAO, and SETUMO VICTOR MOTLOUNG

EFFECT OF ALKALINE TREATMENT ON MORPHOLOGY AND BIODEGRADATION OF BAGASSE AND MAIZE CELLULOSE

This study investigates the biodegradation behaviour of cellulose extracted from sugarcane bagasse (SCB) and maize using chemical treatments involving sodium hydroxide (NaOH), sodium chlorite, and buffer solutions (NaOH and glacial acetic acid). The extraction process yielded cellulose at 38.00% from SCB and 45.14% from maize, based on the weight of the raw material. The resulting celluloses were characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), confirming their structural and chemical integrity. Biodegradability was evaluated through composting tests, revealing weight losses of 9.08% for SCB cellulose and 29.47% for maize cellulose. The higher degradation rate of maize-derived cellulose suggests enhanced biodegradability