Articles

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
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

WOOD RESEARCH Volume 70, Number 2, 2025
LI LILI, LIU WENWEN, LUO ZHIYING, LIU DE, YU JIANFANG, WANG XIMING, ZHANG GUO, and ZHEN JING RU

THE EFFECT OF UV ABSORBERS ON THE LIGHTFASTNESS OF DYED VENEERS

To address the problems of fading, surface yellowing and breakage of dyed veneers under prolonged sunlight, this paper uses ash veneers as raw material and new coccine as dye to investigate the effects of bleaching pretreatment, different concentrations (0.5%, 1% and 1.5%) and types of UV absorbers (benzotriazole, TiO2, nano-TiO2) on the color difference value △E of the dyed veneers in the process of aging by natural light and aging by artificial light. The effect of UV absorbers on the color difference △E of dyed veneers during natural light aging and artificial light aging was clarified. The experimental results show that under the natural light condition, the bleached dyed veneer with 0.5% benzotriazole has the lowest △E value, which is about 1.3, and under the artificial UV irradiation condition, the bleached dyed veneer with 1% TiO2 has the smallest △E value, which is about 0.4

WOOD RESEARCH Volume 70, Number 2, 2025
LIN YANG, PUYAN ZHAO, and QIN YIN

STUDY ON THE HYDROTHERMAL TREATMENT OF KILN-DRIED TIMBER OF RED ALDER

This study used red alder (Alnus rubra f. pinnatisecta) and applied humidity control during storage to shorten the health cycle and enhance preservation effects. Orthogonal testing was conducted to assess the impact of humidity control on drying quality and identify optimal conditions. The results showed that: 1) Post-humidity control, most materials exhibited high surface and low core moisture distribution. Surface moisture difference before and after treatment was largest and negatively correlated with moisture increase. Higher temperatures reduced differences at the same treatment duration. 2) Reasonable humidity control significantly improved drying quality: surface moisture remained stable, elastic and mechanical adsorption creep strains decreased, and residual stress was reduced by up to 59.5% after 7 days of humidity and curing compared to room temperature curing. 3) Moisture treatment initially reduced residual stress significantly then rebounded slightly, with stress elimination efficiency generally higher than room temperature. This indicates that humidity control shortens wood storage and curing cycles. 4) Orthogonal test results identified optimal humidity control conditions as 70°C, 85% relative humidity, and 48 h treatment

WOOD RESEARCH Volume 70, Number 2, 2025
LIN YANG, HONGWEI FAN, and JINGTING ZHENG

EFFECT OF SUPERCRITICAL CO2 DEHYDRATION TREATMENT ON THE JUGLANS MANDSHURICA

Conventional kiln drying (CKD) has a long drying period and is easy to cause drying defects. Supercritical CO2 dehydration (SCD) can quickly dehydrate water-saturated wood to above the fiber saturation point without damaging the microstructure and avoiding drying defects. In this study, Juglans mandshurica was treated by SCD to 40% moisture content, then was oven-dried. CKD specimens were used as a control to investigate the effect of SCD treatment on the wood properties of Juglans mandshurica. In the moisture absorption test, the equilibrium moisture content of the SCD and CKD samples was found to be 8.95% and 8.66%, respectively.The final tangential and radial swelling of the SCD samples were 2.5% and 2.03%, respectively, which were 0.1% and 0.24% larger than those of the CKD samples. In the water uptake test, the equilibrium moisture content of SCD and CKD samples was found to be 104.79% and 117.71%, respectively. The final tangential and radial swellings of SCD specimens were 9.38% and 4.6%, which were 2.35% and 1.16% larger than those of CKD specimens. Also, it was confirmed that the extraction content of SCD specimen was reduced, the chemical composition was unchanged, and the open diameter of the pits was about 1.35 μm at 20 MPa/60°C

WOOD RESEARCH Volume 70, Number 2, 2025
TAMAS HOFMANN, LASZLO TOLVAJ, and ZOLTAN PASZTORY

CHEMICAL CHANGES DURING WOOD CUTTING

Scots pine (Pinus sylvestris) and poplar (Populus euramericana) species were chosen for the experiments.Sawdust was made by a circular saw with a rare tooth spacing for producing bigger particles beside the fine fractions. Particles were separated by a vibration separator with the sieve sizes 1 mm, 0.63mm, 0.315 mm, 0.1 mm and 0.063 mm. Infrared reflectance spectra of the particles were measured to determine the chemical changes generated by the cutting procedure.The experimental results showed that the grinding of wood resulted in bond rupture for all ether bond types appearing in the infrared spectrum. The number of conjugated and unconjugated carbonyl groups in the wood was significantly reduced during the cutting procedure. After bond breaks, oxidation and recombination processes occurred generating compounds similar to the aromatic structure of lignin, which were shown by increases in absorption at 1514, 1271 and 1231 cm-1

WOOD RESEARCH Volume 70, Number 2, 2025
CHUN-WON KANG, MASUMI HASEGAWA, KAWANISHI MARIA, and HARADHAN KOLYA

Short notes. INFLUENCE OF WOOD ANATOMY ON THE DISTRIBUTION OF GUANIDINE BASED FIRE RETARDANTS IN FIVE FAST GROWING JAPANESE HARDWOODS

This study investigates the influence of wood anatomy on the distribution of fire retardant chemicals in five fast-growing Japanese hardwood species (Melia azedarach, Toona sinensis, Choerospondias axillaris, Alnus japonica, and Liriodendron tulipifera). Given Japan’s increasing demand for sustainable and locally sourced materials, fire retardant treatments are critical for enhancing fire resistance in fast-growing hardwoods used for construction. Using low vacuum scanning electron microscopy (SEM), we examined the distribution of fire retardants in cross-section, radial section, and tangential sections, comparing the effectiveness in ring-porous versus diffuse-porous species. Results revealed that diffuse-porous species (Alnus japonica and Liriodendron tulipifera) retained higher levels of fire retardants with a more even distribution. In contrast, ring-porous species (Melia azedarach, Toona sinensis, Choerospondias axillaris) showed the highest chemical concentration at the edges.

WOOD RESEARCH Volume 69, Number 4, 2024
MATEUSZ SZAR, JAROSŁAW KOZAK, BEATA SIEKIERKA, WOJCIECH SPISAK, ANDRZEJ CHLEBICKI, DANIELA MAJERČÁKOVÁ, and FILIP ŠUBÍN

INNOVATIVE CELLULOSE ADSORBER TO INCREASE TREE PROTECTION AGAINST HARMFUL EFFECTS OF ROAD DE-ICING SALT

The study examines the adsorption capacity of compressed cellulose fibres in cylindrical pellets intended for protecting plants and soils from road salt. The innovative adsorbers use short-fibre cellulose waste, which is unsuitable for recycling and is compressed under pressure ranging from 0.1 to 12.0 MPa. Various cylindrical adsorbers were tested and characterised using the Evaporation surface coefficient (ESC). The most efficient absorber with a diameter of 19 mm and a length of 26 mm at a humidity of 6.76% adsorbed brine to 87%. Cellulose adsorbers outperformed previously described Salix viminalis willow chips in de-icing salt capture efficiency (Spisak et al. 2020)

WOOD RESEARCH Volume 70, Number 1, 2025
CHUN-WON KANG, MASUMI HASEGAWA, and HARADHAN KOLYA

EFFECTS OF HOLE PERFORATION AND SURFACE CUTTING ON WOOD ELASTICITY USING ULTRASONIC AND VIBRATION METHODS

This study analyzed how hole perforation and surface cutting affect ultrasonic wave propagation velocity and resonant frequency in wood. While non-destructive evaluation techniques for wood elasticity are well-established, the specific influence of defects like holes and orthogonal cuts on wave behavior remains underexplored. This study aimed to fill this gap by assessing how these defects influence wave behavior and providing new insights into their impact on wood’s mechanical properties. Four softwood species and seven hardwood species were analyzed. In hardwood specimens, ultrasonic propagation velocity and resonant frequency were measured under increasing levels of hole perforation (9, 27, and 45 holes). In contrast, the effects of one and two orthogonal surface cuts were examined in softwood specimens. The results revealed that the ultrasonic propagation velocity decreased noticeably with an increasing number of holes. Meanwhile, resonant frequency exhibited only a slight decrease. In contrast, softwoods displayed minimal changes in ultrasonic velocity but notable reductions in resonant frequency due to surface cutting. This study highlights the differences in continuous wave propagation pathways associated with the two defect types and estimation methods, offering novel insights into wood evaluation techniques

WOOD RESEARCH Volume 70, Number 1, 2025
MATEUSZ SZAR, JAROSŁAW KOZAK, WOJCIECH SPISAK, TIINA TÖRMÄNEN, and ANDRZEJ CHLEBICKI

IMPREGNATED WILLOW WOOD CHIPS (SALIX VIMINALIS L.): A NOVEL SOIL AMENDMENT FOR ENHANCING SOIL QUALITY

This study introduces a novel method of treating willow chips (Salix viminalis L.) by impregnating them with a solution of conventional mineral fertilizers. Modified willow wood chips have the potential to utilize as an innovative soil amendment and offer benefits for agriculture, horticulture and forestry to improve soil water retention capacity, soil fertility and structure. Experimental results indicate the feasibility of developing a product with nitrogen (N) levels from a minimum of 2%, phosphorus (P) levels exceeding 0.5%, potassium (K) levels exceeding 1.5%, and an organic matter content over 90% of the dry weight

WOOD RESEARCH Volume 70, Number 1, 2025
JORGE GARATE-QUISPE, MAURO VELA-DA-FONSECA, PERCY ZEVALLOS-POLLITO, JAIME FERNANDO TUESTA VASQUEZ, TELESFORO VASQUEZ ZAVALETA, ANDREA AUCAHUASI-ALMIDON, REMBRANDT CANAHUIRE-ROBLES, and GABRIEL ALARCON-AGUIRRE

CHARACTERIZING GROWTH, MACROSCOPIC AND MICROSCOPIC ANATOMICAL FEATURES OF OCHROMA PYRAMIDALEFROM SECONDARY FORESTS, PERUVIAN AMAZON

The study aimed to characterize the radial growth,macroscopic and microscopic anatomical features in wood, and determine the rotation time of Ochroma pyramidale in secondary forests of the southeast Peruvian Amazon. We harvested 13 whole slabs of wood from trees of O. pyramidale. A total of 32 radii and 9 cross sections were dated and crosschecked. The study demonstrates that annual growth rings of O. pyramidale have a common growth signal in secondary forests. This species has potential for analyzing the effects of climate on radial growth. Growth rings are visible to the naked eye and demarcated by a dark-colored tangential fibre arrangement. O. pyramidale showed a high growth rate, mean diameter increment was 1.1 cm/year. The results of the selected model suggest that the rotation time or technical cutting shift of maximum production for O. pyramidale is at 12 years. However, considering the demand for softwood, we recommend that six years of rotation

WOOD RESEARCH Volume 70, Number 1, 2025
YINLUAN QIN, XIAOLI PANG, LONGHAI CHEN, XIAORONG ZHENG, WENBANG WEI, DAJUN LONG, and JING TANG

ENHANCED PERMEABILITY OF EUCALYPTUS CLOEZIANA BASED ON NAOH/Na2SO3 AND H2O2 TREATMENTS

The synergistic effects of NaOH/Na2SO3 and H2O2 treatments on enhancing the permeability of Eucalyptus cloeziana wood were investigated. Treated and untreated specimens were analysed for pore size, microstructure, and chemical composition. The results showed that the treated wood had significantly increased average pore sizes and was characterised by cracks in the wood pits. Additionally, the contents of hemicelluloses and lignin structural components decreased, enhancing permeability. The treated wood showed a 1.2- to 1.8-fold water absorption rate higher than untreated wood. These changes result from the reaction of NaOH/Na2SO3 and H2O2 with wood

WOOD RESEARCH Volume 70, Number 1, 2025
OSMAN ÇAMLIBEL and MURAT AYDIN

INFLUENCE OF PARAFFIN ON MDF PROPERTIES AT INDUSTRIAL SCALE

In this study, the effect of paraffin addition on the modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), water absorption (WA), and thickness swelling (TS) properties of fiberboard by density variations was evaluated. Higher mechanical properties were calculated for the paraffin-free board. MOR and MOE of the boards decreased with the increase in density, but not linearly; indeed, fluctuations were observed. Conversely, IB values were increased with the increase in density. The adverse effect of paraffin on the mechanical properties was almost eliminated with the increase in density, particularly for the 750 kg/m³ density profile, except for IB. The WA performance of the boards was significantly increased (58.8%) with the increase in density. Furthermore, advances with the density increase were uplifted by paraffin addition. However, when water repellency properties and advances in WA were taken into consideration, paraffin addition caused the opposite behavior for TS, but around 5.1% decrease in TS was achieved for the 750 kg/m³ density profile

WOOD RESEARCH Volume 70, Number 1, 2025
DOAN VAN DUONG, VAN HUNG HOANG, MASUMI HASEGAWA, and EVGENII SHARAPOV

THE INFLUENCE OF TREE AGE AND RADIAL POSITION ON THE STRESS-WAVE VELOCITY AND TIMBER PROPERTIES OF PINUS MASSONIANA LAMB. PLANTED IN VIETNAM

The main objective of this study is to investigate the influence of tree age and radial position on the structural properties, asair-dry density (AD), modulus of rupture (MOR), modulus of elasticity (MOE) and the stress-wave velocity measured on small specimens (SWVS). Results of analysis showed a highly significant effect of age and radial position on the SWVS, AD, MOR, and MOE. Stress-wave velocity and wood property traits tend to increase with increasing tree age. The SWVS and selected wood properties near the pith were significantly lower than those near the bark. Mean MOR and MOE of the timber had significantly (P<0.001) relationships with SWVS (r = 0.75 and 0.91, respectively), although in the case of MOR a model based on AD alone is slightly better (r = 0.79). There were also significant relationships of acoustic velocity measured in standing trees (SWVT) with mechanical properties measured destructively in small specimens implying that stress-wave method has a good potential for measuring static bending properties of P. massonianaplanted in Vietnam

WOOD RESEARCH Volume 70, Number 1, 2025
QIANHUI HUO, LEI YAN, XINJIE ZHOU, LILI YU, LIHUA HE, XIAO WANG, HUI LI, and LONGZE AN

WEATHERABILITY OF BAMBOO/PPC COMPOSITES MODIFIED WITH IPBC/DDAC AND UV1130

In this study, a compound anti-mold agent IPBC/DDAC and an ultraviolet absorber UV1130 were used to enhance the weatherability of bamboo/polypropylene carbonate (PPC) composites exposed outdoors. The samples were evaluated by mechanical test, surface color difference analysis, anti-ageing test and mold resistance test. The results indicated that the appropriate addition of IPBC/DDAC and UV1130 effectively mitigated the decline in tensile strength and flexural strength caused by changes in environmental factors; however, their impact on the variation in impact strength was not as significant. At the same level of IPBC/DDAC modification, the higher contents of the UV1130 introduction into the composites, the better surface color stability could be obtained. The introduction of appropriate amount of IPBC/DDAC and UV1130 can effectively improve the mold resistance, water vapor and thermal resistance of bamboo/PPC composite, in which the water vapor resistant level could be up to Grade 5, and no obvious cracks or bubbling were observed on the surface of the composites; the anti-mold efficiency of the composites could be above 90%

WOOD RESEARCH Volume 70, Number 1, 2025
LEI YAN, QIANHUI HUO, XINJIE ZHOU, HAN YU, LILI YU, LIHUA HE, XIAO WANG, HUI LI, and DEZHI ZHOU

EFFECTS OF WASTE POLYETHYLENE ON THE PROPERTIES OF BAMBOO/POLYPROPYLENE CARBONATE COMPOSITES

Bamboo-plastic composites were made by bamboo fibers (BF), polypropylene carbonate (PPC) and waste polyethylene (PE), modified with 3-iodo-2-propargyl butyl carbamate/didecyldimethyl ammonium chloride (IPBC/DDAC) as fungicides and UV1130 as ultraviolet absorbent to prolong their service life for outdoor application, in which 10%, 20%, 30%, 40% and 50% of PPC were replaced by waste PE, respectively to reduce their cost. The modified composites were characterized and analyzed by mechanical properties test, surface color difference analysis, and mold resistance test. The results showed that the tensile strength, bending strength and impact strength of BF/PPC/waste PE composites would decrease as the waste PE content increased, and only when the waste PE content was not higher than 20%, the mechanical properties could meet the application requirements for indoors and outdoors. The introduction of IPBC/DDAC and UV1130 could take positive effects on the mechanical properties, surface color stability and mold resistance of BF/PPC composites, while the tensile strength, bending strength and impact strength of BF/PPC/PE composites were 2.36%, 1.85%, and 1.67% lower than the modified BF/PPC composites, as well as the values of ∆L*, ∆a*, and ∆b* of the composites were lower , and the value of ∆E was higher than the BF/PPC modified composites after three months of outdoor exposure. The efficacy levels of the modified BF/PPC and BF/PPC/waste PE composites could be increased to 98.8% and 56.75%, respectively, due to the excellent mold resistance of the combined antifungal agents of IPBC/DDAC

WOOD RESEARCH Volume 70, Number 1, 2025
GÁBOR ORBÁN and ANTAL KÁNNÁR

ASSESSING THE DISMANTLED GLUED-LAMINATED STRUCTURE OF A NATATORIUM AFTER 35 YEARS IN SERVICE

The article describes the results of the investigation of the load-bearing capacity of the recently dismantled roof structure of the Csik Ferenc Natatorium in Sopron, Hungary, after 35 years of service. The investigation was aimed at measuring the tensile strength perpendicular to the grain, shear strength and global bending strength of the beams and comparing it to the appropriate design stress values. The results showed that the tensile and shear strength of the beams fulfilled the criteria of the Eurocode 5 standard. The bending strength of the full size beam meets the Eurocode5 design strength requirements for strength class GL 36h. The bending MOE does not fulfil the criterion for this strength class, but is higher than the mean value of a GL 24h beam