Articles

PRELIMINARY STUDY OF DEPENDENCE OF SMOKE AND CARBON MONOXIDE EMISSION ON HEAT RELEASE RATE FROM FAST-GROWING WOOD SPECIES

The aim of this paper is to create the model for prediction of carbon monoxide release rate (CORR) and smoke production rate (SPR) from heat release rate (HRR) of fast-growing wood species. The model is independent on wood species, thus is suitable for all fast-growing wood species. Three wood species hybrid poplar J-105 (Populus nigra × P. maximowiczii A. Henry), white willow (Salix alba L.) and black locust (Robinia pseudoacacia L.) were used for universal model creation. The heat release rate, smoke production rate and carbon monoxide release rate have been measured at three heat fluxes (25, 35 and 50 kW.m-2) by the cone calorimeter. The average values of CORR and SPR for all investigated wood species were 0.051 g.m-2.s-1 and 0.086 m2.m-2.s-1, respectively. Both dependencies of SPR and CORR on HRR have shown similar trends during the ignition phase (unstable trend) and during the intense burning phase (roughly linear increasing with HRR). The main difference was shown during the steady state phase (dependency of SPR on HRR is stable while dependency of CO on HRR is highly unstable). The results also proved a significant impact of wood density on these dependencies, thus, the neural network for prediction of SPR, CORR from HRR was applied. The coefficients of determination R2 for trained neural networks, for both SPR and CORR, were achieved in the range from 0.96 to 0.97

THE USE OF BORIC ACID AND ANTIMONY OXIDE AS AUXILIARY MINERALS WITH HUNTITE HYDROMAGNESITE TO IMPROVE FLAME RETARDANT PROPERTIES OF WOODDUST COMPOSITES

Boric acid, antimony oxide minerals and huntite hydromagnesite minerals were used as auxiliary minerals in wood composites to change their flammability features. Composite samples were prepared by using different ratios of sawdust, huntite, hydromagnesite, antimony and boric acid combinations. The obtained samples were characterized by scanning electron microscopy (SEM) analysis to determine the structural and morphological properties of the composites. Thermal behavior of the composites was determined by differential thermal analysis-thermogravimetry (DTA-TG). Tensile and three-point bending tests were performed to understand the mechanical properties. Finally, the flame retardant performance of the samples was observed according to UL94 vertical flammability tests. It was concluded that wood composites containing inorganic minerals gained resistance against fire, a good synergistic effect was obtained in different additive types

ANNUAL GROWTH RING CHARACTERISTICS OF QUERCUS CERRIS (L.) TREES GROWN UNDER DIFFERENT CONDITIONS

The study examined the effect of stand composition and soil quality on radial growth of Quercus cerris (L.) grown in Vas County in Hungary. Twelve trees were randomly harvested, and the sampled wood pieces were extracted from the breast-height portion. Wood strips were machine-sanded, scanned for analysis in ImageJ. Climate data were obtained from a database of the Hungarian National Metrological Service. Mean annual-ring width was larger for trees harvested from mixed species planting site. Overall, annual-ring sizes for trees harvested from pure species stand that thrive on poor soils exhibited wider variation (62%). The same plot of trees had a latewood width variation of 82%. Precipitation correlated positively with annual-ring size with weak to moderate coefficient (0.13 – 0.32), whereas maximum temperature negatively correlated with annual-ring size on moderate coefficient (-0.42)

INCREASING THE EFFICIENCY OF ENZYMATIC HYDROLYSIS OF LIGNOCELLULOSIC MATERIALS BY FREEZING PRETREATMENT

This paper describes the differences between the efficiency of enzymatic hydrolysis of selected lignocellulosic materials after pretreatment by cyclic freezing and thawing. It also discusses the analysis of the positive effect of alkaline conditions on pretreatment. The selected materials were Populus alba L., wheat straw from Triticum aestivum L. and Cannabis sativa. Three pretreatment methods were used to compare the efficiency of enzymatic decomposition of cellulose and cellulose accessibility. The best results show the wheat straw pre-treated at -20°C in the freezer with NaOH addition with a concentration of monosaccharides of 56.6 g.l-1 compared to initial hydrolysed material with a concentration of monosaccharides of 24.4 g.l-1. The results show better digestibility of grass compared to wood dendromass

THE OPTIMAL IMPREGNATION AMOUNTS OF FLAME-RETARDANT FOR KOREAN LARCH AND JAPANESE CEDAR BUILDING MATERIALS

In Korea, in accordance with regulations MOLIT notice 2023-24 regarding the flame retardant performance of building finishing materials and fire spread prevention structure, it is mandated that flame-retardant materials have a total heat emission less than 8 MJ/m2. Consequently, our study aimed to determine the quantity of flame-retardant treatment required to meet MOLIT notice 2023-24 for Korean larch and Japanese cedar, as commonly used exterior materials in construction. To this end, we investigated using a cone calorimeter to observe changes in the THR (total heat released) depending on the SCFI (solid content of flame-retardant impregnation). Our simple linear regression analysis indicated that the SCFI needed to satisfy the prescribed flame-retardant standard of 8 MJ/m2 was 93.9 kg/m3 for Korean larch and 144.6 kg/m3 for Japanese cedar. As a result, we established optimal impregnation levels of flame retardant for both species

EVALUATION OF SELECTED MECHANICAL AND PHYSICAL PROPERTIES OF PARTICLEBOARDS CONTAINING WASTE PLASTICS

This article is focused on the research of particleboards (PB) composed of wood particles from spruce logs and recycled crushed plastic granulates. Crushed plastic granulates sized from 1.0 to 4.0 mm were obtained from worn automobiles by recycling, specifically painted and unpainted bumpers. The proportion of plastic granulate in the particleboards represented 10%, 15%, and 20% of the total weight of the composites. In the production of PB, urea-formaldehyde resin and paraffin emulsion were used as a binder and ammonium nitrate was used as a hardener. The aim of the article was to compare the selected properties of PB containing plastic filler with pure PB. Mechanical properties (tensile and bending strength), and physical properties (water absorption and thickness swelling) were evaluated according to EN 319, EN 310 and EN 317. Based on the results, it can be stated that the bending strength and physical properties of PB containing plastic filler were significantly better compared to pure PB. On the contrary, the tensile strength values were lower in most cases

STUDY ON PREPARATION TECHNOLOGY OF HIGH-QUALITY BIOMASS FUEL PELLETS USING CARAGANA KORSHINSKII KOM. POWDER

Caragana korshinskii Kom. powder was used as the experimental material and wheat bran as the binder to produce high-quality biomass molding fuel (BMF) pellets. A series of experiments involving pellet production were conducted in different molding temperatures and at different moisture contents with different percentage of wheat bran by a newly-developed pelletizer using a die heating production method. The biomass molding process was optimized by single factor and orthogonal test with the fuel relaxation density, mechanical durability and molding pressure as indexes. The experimental results showed that the optimum moisture content was 20% by mass percentage of wheat bran is 9% by mass and molding temperature is 140°C in order to get the best quality of high-strength BMF pellets with relative low molding pressure

STUDY ON THE MOST EFFECTIVE COMBINATION OF FLAME RETARDANT AND ANTI-AGING AGENT FOR BAMBOO MODIFICATION

In order to promote the universal application of bamboo materials as well as to provide reference for the study of the performance of bamboo, four kinds of flame retardants (boric acid (BA), borax (BX), ammonium polyphosphate (APP), disodium octaborate tetrahydrate (DOT)), two kinds of ultraviolet light absorbers (UV-531, nano TiO2) were added into waterborne polyurethane (WPU) to synthesize 5 kinds of modified coatings and coated on the surface of bamboo to make test materials. The flame-retardant analysis of the coated samples comprehensively explored the changes in flame retardancy of the test material after treatment. And the anti-aging test was carried out to investigate the color difference and adhesion change of the coating sample. The results show that the optimum flame retardant and anti-aging coating composition was obtained as 20% solid content of WPU, 8g coating amount of modifier, with the mass ratio of BA/BX/APP /DOT/water being 75:75:7:42:600, and the amount of UV-531 added being 1%

EVALUATION OF DYNAMIC AND STATIC MODULI OF ELASTICITY OF HYBRID EUCALYPTUS WOOD FROM DIFFERENT LOCATIONS IN GHANA

This study explores the mechanical properties of hybrid eucalyptus wood, with a focus on dynamic and static moduli of elasticity (MOE), which is crucial for understanding the stiffness behaviour of wood. The research employs acoustic and static measurements on samples prepared from six trees sourced from Winneba and Amantia in Ghana. The results reveal significant variations in static and dynamic MOE, with higher static MOE observed in both Amantia and Winneba samples. However, Winneba and Amantia samples at the tree level were found to be insignificant statistically. The densities of the samples from the two locations, Winneba and Amantia, were found to be significantly different. Correlation studies revealed strong relationships between wood density and static MOE, as well as static and dynamic MOE, providing valuable insights into the comprehensive characterization of the eucalyptus globulus species grown in Ghana

THIN LIGNOCELLULOSIC LINERS BASED OF SPRUCE SHAVINGS

The article is devoted to determining the basic physical and mechanical properties of sheet materials up to 1.5 mm thick based on wood shavings and PVAc glue with a high proportion of water, pressed under high pressure up to 25 MPa and a temperature of around 190°C, so that the softening of lignin caused by the generated steam, allow to create a compact and non-crumbling surface. In order to characterize the physical-mechanical properties of the new wood-based sheet material with minimum thickness and characteristic elasticity, tests according to the CEPI (Confederation of European Paper Industries) standards were adopted. Procedures for tensile strength according to ISO 1924-2 (2008), Burst strength according to ISO 2758 (2014), puncture according to ASTM D781-68 (1973), water absorption according to ISO 5637 (1989) and porosity according to TAPPI Test method T460 were applied

CHARACTERIZATION OF EXTRACTIVE COMPOSITION IN THE WOOD AND BARK OF CAJUPUTI (MELALEUCA CAJUPUTI SUBSP. CAJUPUTI POWELL.) GROWN IN GUNUNGKIDUL, INDONESIA

The aim of this study was to analyze the extractive composition of the wood and bark of cajuput (M. cajuputi subsp. cajuputi) to consider the end use material according to the characteristics of the its extractives. Results showed that the extractives properties of M. cajuputi, i.e. the contents of n-hexane, methanol, hot water extractives and total phenolic content (TPC), flavonoid content (TFC) and total polysaccharides (TSP) were 0.84 to 1.05%, 1.00 to 1.03% and 1.43 to 1.46%, and 19.2 to 38.7 and 23.2 to 27.3 mg GAE/g dried extract, 11.8 to 16.0 and 7.55 to 14.0 mg QE/g dried extract and 79.3 to 102.8 and 148.8 to 165.9 mg Glu/g dried extract, respectively. Bark had higher extractive levels than wood. In addition, TPC and TSP in the bark were greater than in the wood parts, whereas the reverse trend was found in TFC. The relatively high contents of TPC and TFC in the wood and bark suggest that their potential antioxidant properties. Based on the GC-MS analysis, the high content of sterols-steroids (31.4%) and triterpenoids (21.9%) in the bark part will have potential in the field of pharmacology

INFLUENCE OF SITES ON THE PHYSICAL AND MECHANICAL PROPERTIES OF NATIVE TROPICAL WOODS

The Amazon rainforest displays wide ecological diversity, reflected in its wood variation. The study evaluated the influence of different locations on the properties of wood from native tropical species extracted from the Brazilian Amazon. The most frequent species in the locations were selected, and a total of 104 trees were extracted. The logs were sawed breakdown to make beams (50 × 110 × 2,000 mm). The wood density and mechanical resistance of these samples were determined. The wood density ranged of 0.25-1.00 g/cm3, modulus of elasticity and rupture in static bending ranged of 5,982-19,025 MPa and 35-204 MPa, respectively. For compressive strength parallel to the grain, the range was 24-111 MPa; the strength of wood compressed parallel was 20-245 MPa, and the shear strength was 50-245 MPa. The study detected differences in the physical and mechanical properties of the woods regarding the origin of the sites (Amazonas-Pará/Brazil), with the modulus of elasticity and the wood density showing the greatest variations

CLIMATE CHANGE MITIGATION THROUGH CARBON STORAGE AND PRODUCT SUBSTITUTION IN THE HUNGARIAN WOOD INDUSTRY

In our study we estimated under two different scenarios the historic and future carbon balance of the Hungarian harvested wood product (HWP) pool using the HWP-RIAL model. We also estimated the effect of product and energy substitution and the magnitude of avoided emissions based on international substitution factors. According to our results in the period 1985–2021 the average of the HWP net emissions plus substitution effects was -3,800 kt CO2. In this period the 49% of the forest industry-related climate benefits was attributable to carbon storage in forests, while 4% was attributable to carbon storage in wood products and 47% to product and energy substitution. According to our projection the HWP net emissions plus substitution effects could reach -14,994 kt CO2 up to 2050 under an intensified domestic wood processing industry. This means that product substitution benefits could be tripled, while the net removals of the HWP pool could be 5 times higher than the historic values

MODIFIED STARCHES AS A MEAN OF INCREASING THE DRY STRENGTH OF TISSUE PAPERS

Application of agents to increase the dry strength is one of the ways of improving the physical-mechanical properties of papers. In the presented article, we are dealing with the application of modified starches to the pulp mass in order to increase the strength parameters of hygienic papers. In laboratory experiments, 8 types of agents were tested, which differed in charge level, molecular weight and cross-linker level. Strength parameters, porosity and water absorption were evaluated during the laboratory tests. The most important strength parameter in the production of tissue papers is the tensile strength, the most suitable parameters for the production of tissue papers were achieved when applying the product ECO 2777. By monitoring the influence of the dose of starch, it was found that the optimal dose is 3 kg per ton of absolutely dry pulp, when there is an increase in the tensile strength by 18%, the burst strength by 41% and while maintaining the required values of stiffness, porosity and water absorption

OPTIMAL DESIGN OF THE TRADITIONAL CHINESE WOOD FURNITURE JOINT BASED ON EXPERIMENTAL AND NUMERICAL METHODS

In this study, computer aided technology was utilized to improve the traditional grid shoulder mortise-and-tenon joint (GSMTJ). Firstly, the traditional GSMTJ was redesigned through using separated loose tenon by the computer aided design (CAD) software called AutoCAD. And then the mechanical strengths of the traditional GSMTJs and the improved GSMTJs were compared and analyzed using the experimentally validated finite element method (FEM) based on the computer aided engineering (CAE) software called ABAQUS. Finally, the GSMTJs were further investigated from perspective of manufacturing efficiency using the computer aided manufacturing (CAM) software called JDSoft SurfMill. Based on the above simulation analysis, the improved GSMTJ was validated to be equivalent strength, high manufacturing efficiency increasing by 11.5%, low processing load ratio decreasing by 30%, as well as less wood material cost reducing by 3.6% compared with the traditional GSMTJ. The proposed improved GSMTJ was validated to be more suitable to modern wood processing machines. In addition, the methodology of combining the CAD, CAE, and CAM to wood products design was proofed efficient, economic, and feasible, and can be also used in design of other products

VARIABILITY OF ANATOMICAL AND MORPHOLOGICAL TRAITS OF PINUS NIGRA AND PINUS SYLVESTRIS SEEDLINGS AFFECTED BY DIFFERENT CONTAINER TYPE

In the paper was analysed the influence of three different container types, used for cultivation of Pinus nigra and Pinus sylvestris seedlings, on dimensions of their anatomical (resin ducts width, resin ducts number, tracheid number, tracheid width, wood rays height) and morphological (height, root collar diameter, sturdiness coefficient) elements, and on proportion of wood, bark and pith, as well. Two-factorial ANOVA showed that container type affects a lot all investigated anatomical traits by both species, but on the other side, these species varied between each other just in terms of tracheid width and wood rays height. Based on descriptive statistics, significantly lower values of all studied anatomical elements were recorded by biodegradable compared to plastic containers. As for P. nigra seedlings, they showed the best anatomical performance in Plantagrah I, while Hiko V-120 SS was the most suitable for P. sylvestris. The highest proportion of pith and bark was recorded in biodegradable container. As for morphological parameters, such as height and root collar diameter, higher values were recorded by plastic containers

SOME PHYSICAL AND MECHANICAL PROPERTIES OF COCONUT PALM (COCOS NUCIFERA) STEM IN HAINAN ISLAND, CHINA

The physical and mechanical properties of 40-year-old coconut stem were investigated in different radial directions and height positions. The results showed that in the radial direction, the properties of the number of vascular bundles (NVB), density, shrinkage, compressive strength parallel to the grain (CS), modulus of rupture (MOR), and modulus of elasticity (MOE) decreased continuously from the outer area to the inner area, except for the water absorption (WA) value which increased from the outer area to the inner area. The density and MOE decreased from the bottom to the top in the height direction while NVB and WA increased. The shrinkage, CS, and MOE first increased and then decreased from the bottom to the top. NVB in coconut stem affects the density and determines the main mechanical properties of CS, MOR, and MOE. The analysis of variance (two-way ANOVA) showed a significant difference in density, NVB, WA, CS, MOR, and MOE in radial direction and height position. These findings can be useful for the development of new applications for coconut stems, such as in construction, landscaping, or furniture manufacturing, as well as for improving our understanding of their structural characteristics

PREPARATION AND PERFORMANCE OF ANTI MILDEW GLUED LAMINATED BAMBOO

In order to strengthen the anti-mildew and anti-aging properties of bamboo when exposed outdoors, the glued laminated bamboo was impregnated with four different kinds of anti-mildew agents: tebuconazole, 3-Iodo-2-propargyl butyl carbamate (IPBC), NaBF4/didecyl dimethyl ammonium chloride (DDAC), boric acid/borax, and waterborne polyurethane coatings modified with boric acid/borax and triazole (UV1130), nano-TiO2 and nano-SiO2 were coated respectively. The modified coated glued laminated bamboo was characterized and analyzed through the experiments of wear resistance, three-point bending resistance and mildew resistance. The results showed that the glued laminated bamboo impregnated with 0.5% NaBF4/DDAC, and then coated with the waterborne polyurethane modified with boric acid/borax and nano TiO2 (the mass ratio:7.5/7.5/1.0) possessed the best mildew resistance, mechanical properties and weather resistance

SHORT NOTE. THERMAL CHARACTERISTICS OF SENGON WOOD DRYING USING INFRARED AND COMBINED INFRARED-HOT AIR METHODS

This research aimed to determine the thermal characteristics of sengon wood due to drying at temperature of 70, 80, and 90oC with air velocity of 1 and 3 m/s using infrared (IR) and combined infrared-hot air (IR-HA) method. The thermal characteristics analyzed included temperature distribution, reduction in moisture content, and drying rate. The results of drying wood samples using IR method showed that the fastest drying time was obtained at 90oC with air velocity of 1 m/s. However, for combined IR-HA method, the optimal condition was achieved at air velocity of 3 m/s. The largest drying rate attained using combined IR-HA method was 0.27 g/min, while the smallest was recorded at 0.094 g/min with IR method. These results showed that combined IR-HA method produced a more evenly distributed temperature and faster drying time compared to the IR method

COLOR DIVERSITY OF BEECH WOOD WITH A FALSE HEARTWOOD IN THE COLOR SPACE CIE L*a*b*

The color of the false heartwood of Fagus sylvatica L. perceived by the human eye is in a wide range of shades from light brown-yellow to red-brown. The article analyzes the color in the color space CIE L*a*b* of dry wood of the false heartwood type: round, flame, star and marble. The color of the wood was measured with a colorimeter Color reader CR-10. The most colorful is the wood marble with a false heartwood. The results of statistical processing of the measured color values of dry beech wood, marble false heartwood on a planed surface identify it with values on the lightness coordinate L* = 65.2 ± 6.9 and on the chromatic coordinates: red color a* = 13.2 ± 2.3 and yellow b* = 19.2 ± 1.9. The most homogeneous in color is the color of the ring wood of the false heartwood with the coordinate values: L* = 63.7 ± 3.1; a* = 12.6 ± 1.7 and b* = 20.1 ± 1.6. The color diversity of the darkness and yellow-brown-red shades of the wood of the false heartwood is numerically quantified by the values of the total color difference ΔEsx* = 3.9 – 7.5. The presented values of the color of false heartwood beech complement the knowledge about the color of false heartwood and by defining the boundaries of color in the color space CIE L*a*b*, they create space for designers to model the color diversity of compositions and construction-joinery products made of sapwood and false heartwood beech