Articles

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

WOOD RESEARCH Volume 70, Number 1, 2025
LI LILI, LUO ZHIYING, LIU WENWEN, LIU DE, WANG XIMING, and YU JIANFANG

THE EFFECT OF COMBINED FLAME RETARDANTS ON THE PHYSICAL AND MECHANICAL PROPERTIES OF MONGOLIAN PINE

To enhance the flame-retardant properties and physical-mechanical performance of wood, this experiment selected Mongolian pine as the material and employed a vacuum-pressure impregnation method, with different ratios of borax and ammonium polyphosphate (BO:APP) (1:1, 2:1, 1:2) applied and compared with untreated wood (BCW). The treated and untreated Mongolian pine samples were analyzed using scanning electron microscopy (SEM), a universal mechanical testing machine, a limiting oxygen index (LOI) tester, and thermogravimetric analysis (TG) to assess microstructure, weight gain rates, density, physical-mechanical properties, flame retardancy, and thermal stability. Results indicate that the flame retardants were uniformly dispersed within the wood’s pores, achieving excellent impregnation. The weight gain rates and density of the treated wood improved when the weight ratio of borax to ammonium polyphosphate was in ratio1:1 (BO-1:APP-1 group).The weight gain rates was 10.36% and a density of 0.632 cm³/g and the MOE and MOR reached 12,076 MPa and 116.3 MPa, respectively, representing increases of 26.5% and 16.7% compared to untreated samples. The oxygen index of the BCW group was 23.1%, while that of the BO-1:APP-1 group was 42.5%, reflecting an 84% improvement over the BCW group. The thermal decomposition temperature of the treated samples decreased by 50°C, with the BCW group’s char yield at 11.35%, whereas the char yield for treated samples exceeded 20%, reaching 37.44% for the BO-1:APP-1 group, marking a 230% increase compared to the BCW group

WOOD RESEARCH Volume 70, Number 1, 2025
Vladimír Mózer, LUKÁŠ VELEBIL, and ANDREA SMETANOVÁ

INVESTIGATION OF CLT PANEL DEGRADATION DURING HEATING AND COOLING PHASES OF FIRE

The research presented in this paper investigates the behavior of Cross-laminated timber (CLT) under fire exposure during the heating and cooling phases. A sample CLT panel was exposed to a 60 min heating phase as per the ISO 834 standard time-temperature curve, following which it was removed from the furnace and left to cool at ambient temperature. Due to char formation and availability of oxygen during the intended cooling phase, the intensity glowing combustion was growing and resulted in increasing temperatures and even flaming combustion in its latter stages. The char layer thickness doubled during the intended cooling phase under the experimental conditions. Temperature profiles measured parallel and perpendicular to isotherms indicated significant underestimations associated with the perpendicular orientation. The study highlights the need for consideration and further investigation of the cooling phase and its impact on structural design and fire investigation

WOOD RESEARCH Volume 70, Number 1, 2025
JINGGUI WANG, MING LI, SAIYIN FANG, TINGTING DENG, ER ZHUANG ZHAI, CHUMIN CHEN, and KEFEI CHEN

RESEARCH ON WOOD DAMAGE FRACTURE CHARACTERISTICS BASED ON ACOUSTIC EMISSION RA-AF VALUE AND ENERGY CONCENTRATION

To study the acoustic emission (AE) characteristics and fracture properties of wood at different stress stages, three-point bending tests and real-time AE monitoring were carried out on Zelkova schneideriana and Pinus sylvestris var. in this paper. Different stress stages were classified according to AE ringing counts-cumulative AE ringing counts-load curves, damage modes of wood at different stages were identified based on distribution characteristics of RA-AF data, and fracture behavior of wood was predicted by energy concentration k. Results show that distribution characteristics of AE RA-AF data can characterize the types of cracks generated in each stress stage of wood. The crack modes generated by both specimens during three-point bending loading are tension shear composite cracks, and the proportion of tensile cracks is significantly higher than that of shear cracks, but during the elastic-plastic stage, Zelkova schneideriana specimens will produce a large number of shear cracks, whereas Pinus sylvestris var. specimens have predominantly tensile cracks, with only a small number of shear cracks produced before and after fracture. The sudden change in the energy concentration k curve between elastic-plastic deformation stage and fracture stage can be used as a precursor of damage for both specimens under three-point bending test conditions

WOOD RESEARCH Volume 70, Number 1, 2025
NUR SAFITRI, AUDREY KINANTI, IMAM WAHYUDI, and ANDI DETTI YUNIANTI

COMPARISON OF FIBER QUALITY AND ANATOMICAL STRUCTURES OF ACACIA MANGIUM FROM BREEDING ACTIVITIES

This study aimed to analyze the effect of a tree breeding program on the fiber quality and anatomical structure of 10-year-old Acacia mangium wood. There are three trees in each breeding generation, namely the first generation (F0) and the second generation (F1). The results showed the average fiber dimensions of all populations were as follows: First generation has 966.05 µm length, 19.84 µm diameter, and 3.78 µm cell wall thickness, while Second generation has 1046.23 µm fiber length, 20.23 µm fiber diameter, and 3.56 µm cell wall thickness. The genetic improvement treatment showed significant improvement in the fiber dimension. According to the quality classification grade for pulp and paper raw materials, all populations belong to quality class II. Based on the list of the International Association of Wood Anatomists (IAWA), it can be ascertained that the wood anatomical structures of all populations showed no microscopic differences

WOOD RESEARCH Volume 70, Number 1, 2025
JUAN DOMINGUEZ, INGRID CASSANA, and LEIF PORTAL

RELATIONSHIPS BETWEEN WOOD ANATOMY, PHYSICAL PROPERTIES AND COLORIMETRY IN TRICHILIA DAZAE T.D. PENN.: AN ENDEMIC SPECIES OF THE HUMID MONTANE FOREST OF PERU

Trichilia dazae, an endemic tree from the humid montane forests of the Peruvian Andes, plays an important ecological and potential economic role. Despite this, there is a significant gap in the characterization of its wood. This study aimed to analyze the anatomical, physical, and colorimetric properties of T. dazae wood to assess its technological potential and promote its sustainable use. Samples from three trees in the San Carlos district, Bongará, Peru, were collected. Anatomical description and physical properties were evaluated using international standards, while colorimetric analysis was conducted using the CIE Lab* system. The results showed distinct anatomical characteristics, such as diffuse porosity and heterocellular rays, associated with a basic density of 0.64 g/cm³. Significant correlations were found between basic density and anatomical features, suggesting a balance between mechanical strength and hydraulic conductivity. These findings emphasize the species’ value for both structural and decorative applications

WOOD RESEARCH Volume 70, Number 1, 2025
RICARDO DE CARVALHO BITTENCOURT, MATHIAS TEIXEIRA MARÇAL, STÉPHANI CAROLINE DE LANA ARÊDES, GABRIEL MARTINS DAVID, TIAGO GUIMARÃES, GABRIEL DE CASTRO BAIAO BRUMANO, and MARCELO MOREIRA DA COSTA

Short notes. Prolonged Impregnation of Bamboo chipsin Pre-Hydrolysis kraft pulping for Dissolving pulp production

The aim of the article was to compare the feasibility of different impregnation processes of chips and production of soluble bamboo pulp by the pre-hydrolysis kraft (PHK) method.The chips made of Bambusa vulgariswere subjected to prolonged or conventional impregnation with white liquor, followed by the pre-hydrolysis, neutralization, kraft cooking and washing stages. The brown pulp was subjected to a bleaching process using an elemental chlorine-free (ECF) sequence. The results showed that prolonged impregnation provided greater delignification and lower reagent consumption than conventional impregnation. The pulp produced from prolonged impregnation with 14% effective alkali (EA) presented the best properties for dissolution, with intrinsic viscosity of 437 dm3/kg, brightness of 88% ISO, xylan content of 3.48% and glycan content of 94.5%. TAC consumption was low for both impregnations. The study concluded that Bambusa vulgaris can be used in the production of dissolving pulp, mainly for viscose grade

WOOD RESEARCH Volume 69, Number 4, 2024
JÁN KANÓCZ, VIKTOR KARĽA, MICHAL TOMKO, TOMÁŠ BAROŠ, and VIKTÓRIA BAJZECEROVÁ

DESIGN AND ANALYSES OF HYBRID FACADE PANELS CREATED WITH TRANSPARENT WOOD BIO-COMPOSITES

The paper presents the initial results of research focused on the possibilities of using transparent wood for building envelope structural elements in architecture. Sometheoretical analyses of the hybrid envelope panelsmade with different types of transparent wood were carried out. The aimof the study was to assess static and hygrothermal behaviour of such panels. The panels were considered to be two layers of transparent wood bio-composites each 10 mm thickglued to an oak timber frame with only plain air as insulator in the panel.Because only small samples of transparent wood were produced so far, it was considered that mechanical properties of small samples would be retained in large ones as well

WOOD RESEARCH Volume 69, Number 4, 2024
YOSAFAT AJI PRANATA and BAMBANG SURYOATMONO

EXPERIMENTAL STUDY ON FLEXURAL BEHAVIOR OF RED MERANTI (SHOREA SPP.) GLULAM BEAM OF VARIOUS NUMBER OF LAMINAE

This research aims to study flexural behavior of Red Meranti (Shorea spp.) glulam beam of various number of laminae by carrying out testing beams made from four, six, and eight laminae. Four points bending test method according to ASTM 198-22 was applied. The research results show that glulam composed of a smaller number of laminas reaches a smaller flexural rigidity. The empirical equations for flexural strength ratio and modulus of rupture ratio, and the trend of flexural rigidity between glulam and solid proposed in this study can be used in designing the flexural members of timber buildings, timber bridges, and in calculating the deflection of timber beams

WOOD RESEARCH Volume 69, Number 4, 2024
MONIKA STANKOVSKÁ, JURAJ KRIŠTA, ŠTEFAN BOHÁČEK, ALBERT RUSS, and ANDREJ PAŽITNÝ

COMPARISON OF TWO METHOD FOR ISOLATION OF FIBRILLATED CELLULOSE FROM LIGNOCELLULOSIC BIOMASS

Fibrillated cellulose from distillery refuse based on maize starch was prepared by two different procedures. The effect of sonification was evaluated atacid-alkali extractionas well as the type of used acid. The results from the alkali-acid procedure were compared with these obtained by method of steam explosion at different temperatures. The acid-alkali method brings a better result regarding degradation of hemicellulose and lignin as well as cellulose. Lignin/hemicellulose were only released from lignocellulose network using steam explosion at 120-180°C. At higher temperature, the results were comparable with those obtained by acid-alkali method. Similarly pore size distribution of filter paper decreased more significantly when fibrillated cellulose from acid-alkali treatment was applied. After steam explosion, higher extend of longer still fibres remains

WOOD RESEARCH Volume 69, Number 4, 2024
TOMÁŠ MELICHAR, SILVESTR VASAS, JIŘÍ BYDŽOVSKÝ, ŠÁRKA KEPRDOVÁ, AMOS DUFKA, and IVETA NOVAKOVA

INFLUENCE OF PARTICULATE MIXTURE CONTAINING STABILISED WOOD ON LONG-TERM BEHAVIOUR OF WOOD-CEMENT COMPOSITES. CASE STUDY

This paper presents research on the changes in the properties of cement-bonded particleboard modified with particulate mixture (PM). PM replaced 4% of the binder (cement) and 4% of the filler (spruce chips). The cement-bonded particleboards were tested for physical (bulk density, swelling, linear expansion due to relative humidity changes) and mechanical properties (modulus of rupture and modulus of elasticity). Development of phase composition and microstructure by XRD and SEM were also analysed. The long-term behaviour of wood-cement composites was studied over a period of 2 years. The physical, mechanical properties and microstructure of the modified particleboards were compared with commercially produced cement-bonded particleboards from CIDEM Hranice, Inc. There is no intentional change in properties when using PM compared to the reference boards and the values reached the EN 634-2: 2007

WOOD RESEARCH Volume 69, Number 4, 2024
LOYA JAMALIRAD and SAEED NAROUIE

LIGNOCELLULOSIC WASTE OF FURFURAL PRODUCTION FROM BAGASSE AS NON-FOOD FILLER AND SUBSTITUTE FOR UF RESIN IN PLYWOOD MANUFACTURE

The effect of lignocellulosic waste from furfural production of bagasse (LWFPB) as non-food filler for urea-formaldehyde resin (UF) and also substitute a part of UF resin in plywood manufacture was evaluated. LWFPB was used at four levels of 0, 10, 20 and 30% as filler and was replaced with UF resin at three levels of 0, 10 and 20%. Then the physical and mechanical properties of the plywood samples were measured. Results showed that the mechanical and physical properties of plywood were increased compared to the control (with wheat flour filler) when UF resin was used with LWFPB filler. Higher shear strength, MOR and MOE were associated with the use of 30% LWFPB. Besides that, the addition of LWFPB instead of UF resin reduced the mechanical and physical properties of plywood to some extent, but compared to control sample, the best results were obtained with the addition of 10% LWFPB

WOOD RESEARCH Volume 69, Number 4, 2024
RUI JIANG, YUANFEI XU, XUEJIAN YANG, LEI ZHANG, ZHENYU FAN, XIAOYAN GUO, FENG XIAO, LIZHI ZHU, and BINGQIN SUN

THE EFFECT OF COLORANTS ON THE DEGRADATION PERFORMANCE OF WOOD PLASTIC COMPOSITES

The degradation performance of the colorful wood flour/poly (β-hydroxybutyrate valerate) composites (CWPHBVs) in natural outdoor landfill was investigated by some physical, analytical, and microscopic tests. The mass loss rate of the CWPHBVs within 80 days of degradation shows a growth trend and the mass loss rate decreases by more than 20%. With the increase of degradation time, the bending strength of the CWPHBVs continues to decline, the elastic modulus of the CWPHBVs shows a logarithmic decline trend. After 30 days, the bending strength of the CWPHBVs decreases over 50% and tend to be stable. The colorant has a certain inhibitory effect on the degradation. However, with the shedding of the colorant, the effect of the colorant on the degradation is gradually weakened. The addition of colorants reduces the decomposition rate of PHBV and improves the thermal stability of poplar fibers. However, after 20 days, this effect almost disappears

WOOD RESEARCH Volume 69, Number 4, 2024
ALBERT RUSS, ANDREJ PAŽITNÝ, JURAJ KRIŠTA, EMMA WESZELOVSZKÁ, and VLADIMÍR IHNÁT

ENZYMATIC HYDROLYSIS OF STEAM EXPLODED STRAW WITH THE ADDITION OF ACETIC ACID

The effect of steam explosion on the enzymatic hydrolysis of straw was investigated in the presence of 5, 10, 15 and 20% wt. addition of acetic acid. Analysis was performed at temperatures of 160, 170, 180, 190, 200 and 210°C. The concentration of monosaccharides obtained after enzymatic hydrolysis was considered the main indicator of the increased availability of cellulose due to their release into the solution. The results indicate that the addition of acetic acid increases the concentration of monosaccharides, but only at lower temperatures. The temperature of 180°C corresponded to the most effective pretreatment by steam explosion in the presence of acetic acid with the highest concentration of 10%, which corresponds to the conversion of polysaccharides to monosaccharides of 74.78%. At high temperatures above 200°C, the addition of acetic acid results in a decrease in the concentration of monosaccharides due to the high severity factor in the range of 3.94 – 4.24

WOOD RESEARCH Volume 69, Number 4, 2024
KUN DU, YOULI WANG, ZHIHENG ZHANG, MING LI, and SAIYING FANG

THE ATTENUATION CHARACTERISTICS OF DIFFERENT FREQUENCY COMPONENTS OF ACOUSTIC EMISSION SIGNAL DURING PROPAGATION IN ELM AND PINE WOOD

In order to gain a deeper understanding of the attenuation characteristics of different frequency components of acoustic emission signal when propagating in wood, this research conduct pencil lead fracture experiments on the surface of elm and pine specimen. Original AE signals acquired by different sensors are decomposed using 5-level wavelet transform, the attenuation characteristics of different frequency components are studied, and the acoustic emission source is located according to the energy of different frequency components. The results indicate that the propagation distance is the main factor affecting the attenuation of AE signals. The longer the propagation distance, the greater the degree of attenuation. The attenuation characteristics of high-frequency components of acoustic emission signals deviate from the ideal attenuation model after the propagation distance greater than 10 cm. The higher the frequency components of acoustic emission signals, the faster they attenuatewhen propagation in elm and pine specimen

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.