WOOD RESEARCH Volume 70, Number 4, 2025
RENÁTA KUTLÁKOVÁ, PETER RANTUCH, JOZEF MARTINKA, MARGARÉTA TIBENSKÁ, TOMÁŠ ŠTEFKO, and IGOR WACHTER

CHARACTERIZATION OF IGNITION PROCESS OF THERMALLY TREATED WOOD BY CONE CALORIMETER

This study examines the influence of thermal treatment on the ignition properties of Norway spruce (Piceaabies (L.) H. Karst.) and sessile oak (Quercus petraea (Matt.) Liebl.) wood. Using a cone calorimeter both untreated and thermally modified samples (180°C for 6 h) were analysed to determine key fire modelling parameters: combustion efficiency, critical heat flux, ignition temperature, thermal inertia, and thermal response parameter. Obtained results reveal that thermally treated wood exhibits higher combustion efficiency than its untreated equivalent, with spruce generally outperforming oak. The effect of thermal treatment on other properties was species-dependent. Thermally treated spruce showed an increase in critical heat flux and a decrease in both thermal inertia and the thermal response parameter. Conversely, thermally treated oak displayed a reduction in critical heat flux and an increase in both thermal inertia and the thermal response parameter. These results highlight the complex, species-specific effects of thermal modification on the fire behaviour of wood.

WOOD RESEARCH Volume 70, Number 4, 2025
DUŠAN JOKANOVIĆ, VESNA NIKOLIĆ JOKANOVIĆ, JOVANA PETROVIĆ, MARKO MARINKOVIĆ, BOJAN TUBIĆ, ANDREJA LAZOVIĆ, and FILIP JOVANOVIĆ

MORPHO-ANATOMICAL TRAITS OF QUERCUS CERRIS AND Q. RUBRA ONE-YEAR-OLD SEEDLINGS CULTIVATED IN DIFFERENT CONTAINER TYPES

The paper investigated the variability of the morphological-anatomical traits of one-year-old oak seedlings (Quercus cerris L. and Quercus rubra L.) produced in three different container types (Hiko, Plantagrah, biodegradable). A two-factorial ANOVA showed for the morphological characteristics (root collar diameter and height) statistically significant difference between the species and between the containers, too. The interaction between the variability factors (container type and species) also affects height and root collar diameter. As for the obtained results of two-factorial ANOVA for anatomical parameters (wood, bark, pith proportion, and vessel width), statistically significant differences were obtained for all of them between species, as well as between container types. On the other hand, the interaction of container type and species does not affect vessel width and bark content unlike wood and pith proportion. Comparing the species, it can be concluded that the average values of all traits, apart from vessel width, are higher in Q.rubra L. The largest dimensions of all elements regardless of the species were obtained for Hiko, then Plantagrah, and the smallest for biodegradable container.

WOOD RESEARCH Volume 70, Number 4, 2025
VLADIMÍR KUŇA and JOZEF BALBERČÁK

THE INFLUENCE OF PULP BEATING AND PAPERMAKING AGENTS ON THE CHARGE DENSITY OF FIBERS AND COLLOIDAL PARTICLES IN PAPERMAKING WATERS

The first part of the paper is focused on monitoring the impact of the beating process on the charge density of fibres and colloidal particles in water in the production of tissue papers. Three types of pulps most commonly used were tested: long-fibre pine pulp, short-fibre eucalyptus pulp and short-fibre hardwood birch pulp. In the range of beating degrees from 14°SR to 35°SR, the impact of beating on the charge density of fibres expressed as Zeta potential, the charge density of colloidal particles expressed as PCD value and the conductivity of the paper suspension were evaluated. The paper also evaluates the impact of beating on the physical and mechanical properties of laboratory sheets. The second part of the paper is focused on monitoring the impact of papermaking aids, in the production of tissue papers, on the charge density of fibres and colloidal particles in water. The most significant impact was demonstrated by the agent for increasing the wet strength of paper. In these laboratory tests, pulp mixtures were used that were prepared by separately beating individual pulps to a beating degree of 25°SR.

WOOD RESEARCH Volume 70, Number 4, 2025
QINYI GU, HONGHAI LIU, and TAO LI

THE STUDY OF SURFACE DENSIFICATION AND TEMPERATE SUPERHEATED STEAM MODIFICATION FOR RUBBERWOOD

This study aimed to develop a high-value wood composite by surface-densification combined with temperate superheated steam modification technology. Rubberwood boards were hot-pressed, the impact of the peak density and thickness of densified layer on the physical and mechanical properties of wood were studied. In this study the platen temperature was kept constant, after hot-pressing the platen cooling phase was omitted replaced by special compression pressure decreasing and steam discharging technic, which could save much energy and time. Superheated steam treatment (190°C for 1.5 h) and conditioning (110°C for 2 h) were recommended for improving dimensional stability and durability. Study results indicated that the surface hardness and modulus of rupture of surface-densified followed by superheated steam modified rubberwood increased by 55.9% and 41.6% compared with non-densified one respectively. Dimensional stability improved substantially. The durability was improved to ‘durable class’ according to GB/T 13942.1-2009.

WOOD RESEARCH Volume 70, Number 4, 2025
EMRE BIRINCI

INVESTIGATION OF THE EFFECT OF EXTREME TEMPERATURE ON SCREW DIRECT WITHDRAWAL RESISTANCE OF WOOD PLASTIC COMPOSITE DECKING PROFILES

In this study, the effects of extreme temperatures on screw direct withdrawal resistance (SDWR) of wood plastic composite (WPC) decking profiles were systematically investigated. Commercially produced WPC decking profiles were tested at different temperature levels (-40°C, -20°C, 0°C, room temperature, +40°C and +60°C); their effects on SDWR were evaluated by controlling parameters such as screw diameter (3.0 mm and 3.5 mm) and pilot hole diameter (60%, 70% and 85%). Additionally, the relationships between Shore D hardness and SDWR measured at each temperature level were revealed through statistical analyses. The results show that as the temperature increases, Shore D hardness decreases and accordingly, significant decreases occur in SDWR. The highest SDWR was obtained at -40°C temperature, 60% pilot hole ratio and 3.5 mm screw diameter combination. This highlights the influence of material hardness and screw-material interaction on joint performance. According to Pearson correlation analysis, a strong and statistically significant (r=0.939, p=0.0055) positive relationship was determined between Shore D hardness and SDWR.

WOOD RESEARCH Volume 70, Number 4, 2025
YANG ZHENG, MENGQING KE, CHENYANG CAI, XIAO ZHONGYANG, and HONGHAI LIU

COMPARATIVE STUDY ON THE HEAT TREATMENT OF DALBERGIA LATIFOLIA ROXB. WOOD UNDER ATMOSPHERIC PRESSURE AND VACUUM CONDITIONS

This study comparedatmospheric heat treatment (AHT) and vacuum heat treatment (VHT)of Dalbergia latifoliaRoxb. at 180°C for 6 hto improve dimensional stability. Through multiple tests, it analyzed their effects on the wood. Results showed VHT caused milder chemical changes, preserving hydroxyl and lignin structures while AHT severely degraded hemicelluloses. VHT led to lower weight loss 0.45% vs 1.25%, better dimensional stability with a greater reduction in radial swelling 0.84% vs 1.34%, higher mechanical strength (modulus of rupture: 118.22 MPa vs 95.83 MPa; modulus of elasticity 9361.50 MPa vs 8558.34 MPa), and a smaller color change ΔE*: 9.79 vs 18.65. Overall, VHT can balance performance improvement and minimize damage to the wood’s structure and aesthetics.

WOOD RESEARCH Volume 70, Number 4, 2025
MIKKEL NÜSSLER, JOHN BANG MATHIASEN, and JACOB KJÆR ESKILDSEN

DECAY RESISTANCE AND FIRE CLASSIFICATION OF SURFACE-CARBONIZED SCOTS PINE WITH POST-CARBONIZATION LINSEED OIL AND SODIUM SILICATE TREATMENT

Todetermine the effect on decay resistance and fire classificationof applying linseed oil or a sodium silicate solution to surfacecarbonized Scots pine,two different experiments were conducted. AnAWPA E10 standard (AWPA 20216) soil block test was conducted to determine the decay resistance of eight unique treatment configurations, and fireclassification following the EN 13823:2010+A1:2014 / EN 14915:2013was conducted to determine the fire classification of façade panels treated with pure linseed oil and a 40/60 mix of linseed oil and sodium silicate respectively. The study showed that decay resistancemeasured as average mass loss (AML%) improves significantly by surface carbonization butdepends on the intensity of the treatment as well as the application of surface sealing substances applied post-carbonization. Carbonized Scots pine façade panels without any post-carbonization treatment as well as carbonized Scots pine treated with sodium silicate or a 40/60 mix of linseed oil and sodium silicate solution obtained an EN 13823:2010+A1:2014/ EN 14915:2013 B-s1,d0 fire classification. Carbonized Scots pine treated with pure linseed oil did not obtain any classification under EN 13823:2010+A1:2014/ EN 14915:2013.