Static Bending Strength Research Articles

Effect of different initiators on the properties of diacetone acrylamide grafted starch-based adhesive

Environmentally friendly and non-toxic bio-based adhesives are emerging as the most promising substitutes for petroleum-based adhesives, attracting increasing attention. This work involved the synthesis of a starch-based adhesive for particleboards by grafting diacetone acrylamide (DAAM) onto starch. The graft polymerization was initiated using three different initiators: ammonium persulfate (APS), hydrogen peroxide (H2O2)/ammonium ferrous sulfate system, and ceric ammonium nitrate (CAN). A comparative study was conducted to assess the varying effects of these initiators. The results showed that in the graft copolymerization of starch with DAAM, different initiators produced different types of free radicals, and CAN initiation produced alkyl radicals and long-chain alkyl radicals with a peak total spin value of 3.96 × 1015, and thus had the highest grafting efficiency and grafting rate of 72.59 % and 16.75 %, respectively. From the comparison of the total number of spins, it can be seen that CAN is more targeted for starch initiation. In addition, characterization results from Fourier transform infrared spectroscopy and confocal Raman spectroscopy showed that DAAM underwent a graft copolymerization reaction with starch. Notably, the adhesive initiated by CAN demonstrated the highest water resistance and mechanical strength, with an absorption thickness expansion and static bending strength of 8.52 % and 10.56 MPa, respectively.

EVALUATION OF PROPERTIES OF WOOD PLASTIC COMPOSITES MADE FROM SEVEN TYPES OF LIGNOCELLULOSIC FIBERS

This article aims to investigate the characteristics of wood plastic composites (WPC) prepared from polyethylene (PE) reinforced with lignocellulosic fibers derived from the xylem and bark of Masson pine, fir, cypress, as well as from Moso bamboo. The surface polarity and elemental composition of fibers were determined through contact angle measurements and X-ray photoelectron spectroscopy (XPS). The lignocellulosic fiber/PE composites were manufactured through hot-pressing technique, and their water absorption, mechanical properties, and mildew resistance were evaluated. The results revealed that the surface free energy of xylem fibers was higher than that of bark fibers among the three conifer species. XPS analysis showed that the O/C ratio of bark was consistently lower than that of xylem fiber. Among the three conifers, the Masson pine bark had the lowest O/C ratio (22.25%), while its xylem fibers had the highest ratio of 41.64%. WPC made with bark fibers had better water resistance. Additionally, the composites reinforced with xylem fibers showed superior static bending strength, impact strength, and mildew-resistant properties as compared to the composites reinforced with bark fibers. WPC made from bamboo fibers exhibited the best water resistance, with a water absorption rate and thickness swelling rate of 1.83% and 1.42%, respectively. They also had the highest static bending strength, elastic modulus, and impact strength, at 41.31 MPa, 3.82 GPa, and 10.24 kJ/m2, respectively. The WPC made from fir xylem fibers showed the most effective mildew resistance, with the smallest damage (0.50).

The Influence of Hemp Fibers (Cannabis sativa L.) on the Mechanical Properties of Fiber-Gypsum Boards Reinforcing the Gypsum Matrix.

The modern construction industry is looking for new ecological materials (available, cheap, recyclable) that can successfully replace materials that are not environmentally friendly. Fibers of natural origin are materials that can improve the properties of gypsum composites. This is an important issue because synthetic fibers (hardly biodegradable-glass or polypropylene fibers) are commonly used to reinforce gypsum boards. Increasing the state of knowledge regarding the possibility of replacing synthetic fibers with natural fibers is another step towards creating more environmentally friendly building materials and determining their characteristics. This paper investigates the possibility of manufacturing fiber-gypsum composites based on natural gypsum (building gypsum) and hemp (Cannabis sativa L.) fibers grown in Poland. The effect of introducing hemp fibers of different lengths and with varying proportions of mass (mass of gypsum to mass of fibers) into the gypsum matrix was investigated. The experimental data obtained indicate that adding hemp fibers to the gypsum matrix increases the static bending strength of the composites manufactured. The highest mechanical strength, at 4.19 N/mm2, was observed in fiber-gypsum composites with 4% hemp fiber content at 50 mm in length. A similar trend of increased strength was observed in longitudinal tension. Again, the composite variant with 4% fiber content within the gypsum matrix had the highest mechanical strength. Manufacturing fibers-gypsum composites with more than 4% hemp fiber content negatively affected the composites' strength. Mixing long (50 mm) hemp fibers with the gypsum matrix is technologically problematic, but tests have shown a positive effect on the mechanical properties of the refined composites. The article indicates the length and quantity limitations of hemp fibers on the basis of which fiber-gypsum composites were produced.

Viscoelasticity and impact behaviour of green epoxy bio-composites made of date palm leaflets

Natural fibres can replace traditional synthetic fibre composites in applications for which sustainability is a critical aspect. Elghas date palm leaflets in their natural state and with handwoven fabric reinforcements—the latter from customary and regional carpet productions—are included into new bio-based composites that are produced and characterized in this work. The two classes of bio-composites have the same weight fraction in terms of reinforcement. The date palm leaflets reinforcements are dispersed in a green resin matrix. Bio-composites reinforced with leaflets tree have twice the static bending strength than those with leaflets fabric reinforcements. The viscoelastic behaviour of those bio-composites shows an opposite trend, with the laminates reinforced with leaflets fabric being the least sensitive. For an impact energy of 3 J, the strength of bio-composites with leaflets fabric is double than the analogous value shown by bio-composites with leaflets tree. The impact strength however increases by 4.7 times for lower impact energies of 1 J. The results shown here further demonstrate the possibility of developing bio-composites from agro-industrial products, waste, and local textile traditions for secondary structural applications.

Steam explosion-treated mushroom substrate for robust and water-resistant wood composites

Despite its significant biomass content, mushroom substrate (MS) is often carelessly discarded as waste following the harvest of edible fungi. Therein, we harnessed the power of steam explosion (SE) to liberate fibers from discarded MS and substantially increase their surface area for improved binding. Consequently, we successfully fabricated robust and water-resistant wood composites via the hot pressing (HP) technique. Our research underscored the pivotal role played by the substantial lignin content (42.5 ± 2.1%) within waste MS, reinforcing the wood composites and endowing them with exceptional resistance to water-resistant properties. The wood composite derived from waste MS yielded outstanding outcomes in internal bond strength, static bending strength, and thickness swelling, registering at 4.9 MPa, 28.0 MPa, and 30.6%, respectively. These discoveries present a pioneering approach for efficiently utilizing a significant amount of MS.

Wood Quality of Young Tectona grandis L. f. Trees and Its Relationship with Genetic Material and Planting Site in Mato Grosso, Brazil

Tectona grandis L. f. (teak) is highly valued in the international market, but its volume and properties vary depending on its genetic material and planting site. Evaluating these factors is crucial for promoting new plantations. Therefore, this study aimed to assess the impact of genetic material (clones TG1 and TG3 and seminal material) and planting site (Nova Maringá and Água Boa, Mato Grosso, Brazil) on morphological parameters (heartwood, sapwood, bark, pith proportions, and pith eccentricity), physical properties (shrinkage and air-dry density), and mechanical properties (static bending strength—fm, compressive strength—fc0, Janka hardness—fH90, and shear strength—fv0). For this purpose, we sampled five trees aged 13 years per genetic material from commercial plantations. In Nova Maringá, trees exhibited, on average, 56.07% heartwood, while in Água Boa, this value was less than 50%. Seminal material showed the lowest percentage of heartwood (49.2%). The pith percentage was significantly greater in Água Boa than in Nova Maringá, regardless of the genetic material. We observed the highest standard deviation (5.61) in pith eccentricity for the seminal material. Both the planting site and genetic material influenced the air-dry density (~12% moisture content), which ranged from 0.535 to 0.618 g·cm−3. Trees grown in Nova Maringá produced wood with higher dimensional stability than those from Água Boa, exhibiting a 14% lower radial shrinkage and a 6% lower volumetric variation. In Nova Maringá, the wood from the seminal material exhibited greater resistance. On the other hand, in Água Boa, that material showed lower resistance (fv0, fm, and fc0), or there was no significant difference (fH90) compared to the clonal materials. When comparing the clonal materials (TG1 and TG3) at each planting site, they demonstrated similar mechanical properties. The variability in physical and mechanical properties among different genetic materials and planting locations highlights the need to select appropriate teak genetic materials for each region. We concluded that more productive teak clones can be selected without compromising the physical and mechanical properties of the wood.

Study on Phenol-Formaldehyde Resin-Montmorillonite Impregnation and Compression Modification of Chinese Fir.

In this study, a phenol-formaldehyde resin-montmorillonite intercalation composite solution was used as a modifier to treat Chinese fir via impregnation and compression. The basic characteristics and wettability of the PF (phenol-formaldehyde)-montmorillonite impregnation solution were analyzed. The effects of the solid content of PF, the quantity of montmorillonite, and the impregnation time on the impregnation weight gain of Chinese fir were studied through orthogonal experiments. The results showed that when the amount of montmorillonite was 1%, the wettability of the PF-montmorillonite impregnation solution performed the best, the curing time was short, and the curing strength was high. The optimal impregnation process consists of a PF solid content of 25%, an impregnation time of 120 min, and a montmorillonite ratio of 1%. Under these conditions, the modified Chinese fir was prepared via hot pressing. The effects of the addition of montmorillonite and different levels of compressibility on the physical and mechanical properties of modified wood were studied. The physical and mechanical properties were found to be better when the compression ratio was 33%: the density increased from 0.33 g/cm3 to 0.58 g/cm3; the surface hardness increased from 33.6 HD to 70.9 HD; the static bending strength increased from 60.4 MPa to 98.7 MPa; and the elastic modulus increased from 6 390 MPa to 11 498 MPa. After 30 days of release, the compression rebound rate was 3.97%. Meanwhile, the micromorphology and heat resistance of the impregnated compressed Chinese fir showed that the PF-montmorillonite impregnation solution entered into the cell cavity and intercellular space of the Chinese fir and formed a good composite, thus improving the water resistance, heat resistance, and physical and mechanical properties.

Green recyclable biocomposite prepared from lignin and bamboo

Pursuing green and recyclable biocomposites is crucial to promoting sustainable development and carbon balance in the wood-based panel industry. In this study, bamboo and lignin were used as raw materials to create a high-performance biocomposite with better mechanical properties. The biocomposite demonstrates an impressive flexural strength of 97.20 MPa and a tensile strength of 41.43 MPa. These values represent a remarkable increase of 121% and 133%, respectively, compared to traditional fibreboard. This could be due to the lignin in the black liquor undergoing a glassy state transformation during hot pressing and acting as an adhesive to bind bamboo fibres tightly. As a result, the fibres are interconnected by hydrogen bonds and strong chemical bonds. During the recycling experiment, the Hot-pressed B&B20 underwent crushing and partial mixing with bamboo powder in a 1:3 ratio. Despite undergoing this process three times, its strength remained relatively unchanged, with tensile strength ranging from 89.53 to 98.32 MPa and static bending strength ranging from 38.79 to 40.52 MPa. Furthermore, the Hot-pressed B&B20 exhibits excellent machinability, hydrophobicity, heat resistance, and environmental friendliness, which makes it a highly competitive product.

Physico-Mechanical and Energy Properties of Pine (Pinus sylvestris) and Beech (Fagus sylvatica) Wood from Railroad Ties

The objective of the present work was to determine the physico-mechanical and energy properties of pine (Pinus sylvestris) and beech (Fagus sylvatica) wood from railroad ties. The ties were divided into internal and external parts as well as into parts impregnated and unimpregnated with creosote oil. The effects of creosote impregnation on wood hardness, compressive strength parallel to the grain, static bending strength, and calorific value were studied. The obtained results show that the parameters of the analyzed samples meet the standard requirements (EN 338) for construction wood (compressive and bending strength class: C50—pine; D70—beech). Depending on the particular property being studied, both pine and beech samples belong to the highest or one of the highest wood quality classes. Creosote oil considerably increased wood density (by 9% for beech and 19% for pine) but did not affect its hardness. Creosote impregnation significantly improved the compressive strength parallel to the grain of both wood species (beech: σc=51.99 MPa (IN); σc=57.78 MPa (OUT); pine: σc=36.56 MPa (IN); σc=42.45 MPa (OUT)); in the case of static bending strength, its value was increased for beech wood (σg=106.13 MPa (IN); σg=113.18 MPa (OUT)) and reduced for pine wood (σg=66.34 MPa (IN); σg=82.62 MPa (OUT)). The oil contained in wood from ties significantly elevated its calorific value (by 25% for beech and 10% for pine). Unfortunately, the presence of creosote oil currently prevents wood from railroad ties from being reused as the oil is deemed hazardous and carcinogenic. However, if it were possible to isolate the unimpregnated parts of railroad ties, they could be reapplied for construction or other uses.

Керамика на основе сложнооксидного твердого раствора диоксида циркония в тетрагональной форме для ортопедической стоматологии

The paper deals with physical and mechanical properties of ceramic material containing complex oxide solid solution Zr1–n[YbNd]nO2 and corundum microfase, taking into account aesthetic and strength requirements of clinical practice of prosthetic dentistry. It has been shown that the developed ceramic has a static bending strength of 850 MPa and according to the international standard ISO 6872:2015 “Dentistry – Ceramic materials” belongs to the 4th and 5th class of dental ceramic materials. This makes it possible to use it for the manufacture of not only single crowns, but also four-units dentures of any localization and any type of fixation. The developed ceramics meet the requirements of prosthetic dentistry and color characteristics, have high opacity, which makes it possible to mask the color of supporting structures.

Novel adhesive based on black soldier fly larvae flour for particleboard production

Protein-based adhesives are receiving considerable attention due to their potential to contribute to the development of environmentally friendly materials. Black soldier fly larvae (BSFL) can convert organic waste into high value-added products, such as proteins and fatty acids. The objective of this study is to formulate adhesives from BSFL flour and evaluate their suitability in the production of particleboards. To expose the functional groups of the proteins for reaction with the wood, denaturation strategies involving alkaline treatments were assessed. The effectiveness of these treatments was evaluated through Bradford solubility, SDS-PAGE, and FTIR analysis. Bradford analysis confirmed that the alkali treatment increased the protein solubility from 10.1 g/l for 0 M to 89.1 g/l for 1 M. FTIR analysis revealed changes in the relative intensity of bands attributable to the Amide I, II, and III regions, which are associated with the α-helix and β-sheet structures. The adhesive was applied in the manufacturing process via spraying, requiring an evaluation of the rheological properties of different formulations. Based on the rheological properties, the viscosities of 0.25 M and 1 M were measured at 0.082 Pa·s and 0.113 Pa·s, respectively, falling within the suggested range for particleboard manufacture. Subsequently, eucalyptus wood panels were manufactured using the BSFL-based adhesives, and their mechanical properties as well as water resistance were evaluated. Static bending and tensile strength perpendicular to the surface testing revealed that boards produced with BSFL adhesive exhibited mechanical values comparable to those of commercial resins. The performance of the manufactured materials was compared with the minimum standards outlined in international regulations.

The Preparation and Performance of Bamboo Waste Bio-Oil Phenolic Resin Adhesives for Bamboo Scrimber

Bamboo is a fast-growing plant with properties such as low cost, abundant resources, and good carbon sequestration effect. However, the swift growth of bamboo resources generates an immense quantity of processing waste, which is necessary to effectively utilize bamboo processing waste. The leftovers from bamboo processing can be reutilized by fast pyrolysis to prepare renewable bio-oil. In this study, bamboo bio-oil was partially substituted for phenol to synthesize phenolic resin with different substitution rates under the action of an alkaline catalyst, and then to serve as the adhesive to produce bamboo scrimber. Bamboo bundles were impregnated with synthetic bio-oil phenolic resin to create bamboo scrimber, which was subsequently hot-pressed. The research shows that modified phenolic resins with a bio-oil substitution rate of under 30% have good physical and chemical properties, while the free aldehyde content of phenolic resin with 40% bio-oil substitution exceeds the limit value (0.3%) specified in the Chinese National Standard. The thermal stability of phenolic resins was also increased after bio-oil modification, indicated by the movement of the TG curve to higher temperature ranges. It was found that the bamboo scrimber prepared with 20% BPF resin adhesive had the best comprehensive properties of a good mechanical strength, hydrophobicity, and mildew resistance, particularly with an elastic modulus of 9269 MPa and a static bending strength of 143 MPa. The microscopic morphology showed that the BPF resin was well impregnated into the interior of the bamboo bundle and had a compact bonding structure within the bamboo scrimber. The anti-mold performance experiment found that the bio-oil-modified resin increased the anti-mold level of the bamboo scrimber from slightly corrosion-resistant to strong corrosion-resistant. The conclusions obtained from this study have a good reference value for achieving the comprehensive utilization of bamboo, helping to promote the use of all components, reduce the production cost of bamboo scrimber, and improve its mildew resistance performance. This provides new ideas for the development of low-cost mildew resistant bamboo scrimber novel materials.

Study on the Characterization of Physical, Mechanical, and Mildew Resistance Properties of Enzymatically Treated Bamboo Fiber-Reinforced Polypropylene Composites

The enhancement of the physical and mechanical properties and the anti-mildew performance of wood–plastic composites are of great significance for broadening their application field. In this research, bamboo fibers underwent treatments with safe, environmentally friendly bio-enzymes. Subsequently, a bamboo–plastic composite (BPC) was developed using the modified bamboo fibers and polyethylene. The effects of biological enzymatic treatments on the surface free energy, the chemical composition of the bamboo fibers, water resistance, thermal stability, bending performance, impact performance, and anti-mildew performance of the BPC samples were analyzed. This study revealed that treating bamboo powder with bio-enzymes (xylanase, lipase, laccase, pectinase, hemicellulase, or amylase) decreased the surface free energy and the polar components of the bamboo fibers while improving the surface O/C atomic ratio of the bamboo fibers. These enzyme treatments enhanced the water resistance, bending performance, and anti-mildew performance of the BPC samples. However, on the whole, the thermal stability of the composites decreased. Particularly, after hemicellulase treatment, the composites had the lowest water absorption, reflecting a decrease of 68.25% compared to the control group. With xylanase modification, the 24 h water absorption thickness swelling rate of the composites was the lowest, reflecting a decrease of 71.27% compared to the control group. After pectinase modification, the static bending strength and elastic modulus of the prepared composites were the highest, with an increase of 15.45% and 13.31%, respectively, compared to the unmodified group. After xylanase modification, the composites exhibited the best anti-mildew effect, with an anti-mold effectiveness of 74.67%. In conclusion, bio-enzyme treatments can enhance the physical and mechanical properties and anti-mildew performance of BPCs. This research provides a theoretical foundation for the preparation of high-performance wood–plastic composites.

Inorganic-accelerated aging method: An efficient and simple strategy to obtain antique Chinese fir wood for the restoration of ancient wooden architecture

Ancient wooden architectures, the precious material cultural heritages of mankind, were faced with huge potential safety hazards because of the excessive aging and natural disaster. Replacing failed wood structure with antique wood is a proper and sustainable method for the repairment and reinforcement, however restricted by the lack of antique wood and mature wood antique technology. In this work, an inorganic-accelerated aging method was put forward to simulate the aging of Chinese fir wood. The as prepared antique wood exhibited a very similar surface color to that of the ancient wood, with a small chromatic aberration of only 4.4. The change of chemical compositions after inorganic-accelerated aging was also explored that hemicellulose was degraded greatly accompanied by the partly degradation of lignin and amorphous cellulose, which were similar to the nature aging process and resulted in an increase of wood crystallinity. Besides the as obtained a-W exhibited satisfactory mechanical strength, of which the bending modulus, static bending strength and compressive strength was 97.7 %, 93.4 % and 93.6 % of the ancient wood, respectively. This work provides a promising strategy for the preparing of antique wood, which is of great significance for the restoration of ancient wood architectures.

A new type of engineered wood product: Cross-laminated-thick veneers

The global scarcity of high-quality solid wood resources has propelled efforts towards developing high value-added products utilizing fast-growing wood. However, the inherent low quality of fast-growing wood poses a significant challenge for its use in engineered wood products. In response to this challenge, this study focuses on the transformation of larch logs into a novel engineering wood product termed cross-laminated-thick veneers (CLTV). The process involves rotary cutting larch logs into 7.5 mm thick veneers, followed by hygrothermal treatment to alleviate stress, and ultimately assembling layers of thick veneers oriented at right angles, securely bonded to form structural panels. The investigation into the mechanical properties of CLTV reveals promising results. The static bending strength and modulus of a 15-layer CLTV with a thickness of 105 mm exhibit noteworthy values of 62.29 MPa and 10986 MPa, respectively. These values stand in comparison to the performance metrics of cross-laminated-timber (CLT) with only 3 layers, indicating the viability of CLTV as a competitive alternative. Additionally, the formaldehyde emission from CLTV measures at a minimal 0.010 mg/m3, while total volatile organic compounds are limited to 47 μg/m3. The development of CLTV emerges as a sustainable solution to the shortage of high-quality solid wood resources. Its comparable performance to traditional materials such as CLT positions CLTV as an eco-friendly alternative for engineered wood products applicable in diverse global building systems. The minimal formaldehyde emission and low volatile organic compounds further emphasize the potential positive impact of CLTV on both the construction industry and broader environmental sustainability initiatives worldwide. This study sets the stage for advancing engineered wood products, addressing resource constraints, and contributing to sustainable practices in the global construction sector.

Influence of Machining Modes and Negative Temperature on the Static Bending Strength of Carbon Fiber Reinforced Plastics

Influence of Machining Modes and Negative Temperature on the Static Bending Strength of Carbon Fiber Reinforced Plastics

Effects of pre-heating treatment parameters on dimensional stability and mechanical properties of densified Chinese fir

Pre-heating treatment performed by heat plate is an efficient wood softening method that could improve the dimensional stability and mechanical properties of densified wood, having great potential to industrialize. To optimize the properties of densified Chinese fir softened by this method, an improved understanding of the pre-heating treatment parameters is required. An orthogonal experiment with three factors and levels was used in this study to investigate the effects of the pre-heating treatment parameters including heating temperature, duration time and moisture content on set recovery, static bending strength (MOR), modulus of elasticity (MOE) and compression strength parallel to grain (CSP). Chinese fast-growing fir with dimensions of 400 mm(L) 60 mm(T) 40 mm(R) was prepared as raw materials, and the wood densification process including softening, pressing and fixation was performed using a hot-press. The test results suggested that moisture content was the most significant factor influencing set recovery, MOR, MOE and CSP. Although the effect of temperature on MOE and CSP was not significant, it greatly affects set recovery and MOR. Moreover, the effect of duration time changes within the range of 10 min to 30 min was slight in all of the responses in this study. The mechanical properties of densified Chinese fir improved substantially with the increase in moisture content. The values of MOR and MOE raised to 95.17 MPa and 15.43 GPa respectively when moisture content raised from 30 % to 50 %, increased by 32.5 % and 21.8 %. The set recovery induced by moisture adsorption and water absorption decreased from 7.23 % to 3.09 % and from 20.9 % to 12.7 % respectively indicating that the dimensional stability of densified Chinese fir improved significantly with the increase of moisture content from 30 % to 50 %. The conditions of pre-heating treatment at a temperature of 120 ℃, duration time of 20 min and moisture content of 50 % were found to be the optimum parameters for manufactured densified Chinese fir. The proposed pre-heating conditions could be a recommendation for industrial production.

STUDY ON PREPARATION AND PROPERTIES OF ANTI-ULTRAVIOLET AGING WOOD-PLASTIC COMPOSITES

The degradable wood-plastic composites (WPC) were prepared by compression molding in this study. Polylactic acid (PLA), poly (butylene adipate-co-terephthalate) (PBAT) and salix powder were used as the main raw materials and nano-titanium dioxide (nano-TiO2) was used as anti-ultraviolet filler. The results show that when the addition amount of nano-TIO2was 2%, the static bending strength and elastic modulus of WPC reach 41.88 MPa and 3730MPa, respectively, which can meet the commercial application of WPC in building formwork. At this time, the composite material has a better effect of absorbing and reflecting ultraviolet light. The static bending strength, elastic modulus, tensilestrength and impact strength of WPC were reduced by 68.3%, 61.5%, 51.9% and 57.4%, respectively. The mass loss rate and water absorption were 6.1% and 22.6%, respectively, that shows its good degradation performance. This study provides a low-cost and simple method for the design of anti-UV aging, high-performance and degradable WPC, which has broad application prospects inpackaging, construction and other fields.

Justification of the Manufacturing Plywood Technology on Dry Glues

The use of environmentally safe technologies in the plywood production encourages the use of dry powder mixtures of polyester resin used for gluing veneer. The work presents the results of studies of some characteristics for plywood, which was product on the basis of polyester resin. As a result of experimental studies, the expediency of manufacturing plywood on dry adhesive mixtures of polyester resins has been substantiated. Since the limit of static bending strength along the fibers of the plywood face layers exceeds the standard value. The resistance to chipping on the glued layer of plywood also did not decrease and exceeds the standard value both after dry exposure and after soaking. The studied plywood is characterized by reduced moisture absorption properties. This is due to the thermal modification of the veneer. It was established that with an increase in the modification temperature to , moisture absorption decreases by more than 3.5 %. Thus, the obtained research results allow us to purposefully solve further problems related to the creation of new technologies for the wood products manufacture and to determine the conditions of their operation at various facilities.

Sifat Fisika dan Mekanika Kayu Acacia aulacocarpa dari KHDTK Wanagama

This study aims to determinethe physical properties and mechanical properties at axial (base, middle, and top) and radial (near the pith, middle, and near the bark) positions, as well as the relationship between the specific gravity and mechanical properties of Acacia aulacocarpa wood. Three 27-year-old trees planted at KHDTK Wanagama wereused. Wood physical and mechanical propertieswere tested per British Standard 373:1957. The statistical analysis used was a two-way ANOVA and a follow-up test of Tukey HSD. The results showed that the average moisture content was 98.95%; the green and air-dry sepesific gravity were 0.58 and 0.61. Radial, tangential, and longitudinal shrinkage from green to oven-dry conditions (total shrinkage) were 2.02%, 5.09%, and 0.33%. The tangential/radial (T/R) ratio was 2.80%. The static bending strength of stress at proportion limit, MoE, and MoR were 498.13 kg/cm2, 116.16x1000 kg/cm2, and 1043.68 kg/cm2, respectively. The compressive strength parallel to the grain and perpendicular to the grain were 596.05 kg/cm2 and 227.25 kg/cm2, respectively. The results of the variance analysis showed that the radial position factor has a significant effect on green moisture content, green and air-dry specificgravity, total radial shrinkage, T/R ratio, static bending strength at stress of proportion limit, MoE, MoR, compressive strength parallel to the grain, and compressive strength perpendicular to the grain. However, the axial position factor did not show any significant differences in the physical and mechanical properties of the wood. Furthermore, air-dry specific gravity has a significant moderate to high positive correlation with all mechanical properties.
 Keywords: Acacia aulacocarpa, physical properties, mechanical properties, axial position, radial position