WOOD RESEARCH Volume 68, Number 3, 2023
Yoshikazu Mori, Mio Nakajima, Akihiro Ishida, Noboru Ito, Yohei Kurata, Kazumasa Shimizu, Yoshihiro Katayama, Makoto Kiguchi, Kana Yamashita, Takeshi Fujiwara, and Mario Tonosaki

Changes in Hemicellulose Structure Associated with the Transition from Earlywood to Latewood at Juvenile Wood in Cryptomeria Japonica

The chemical composition and variations in chemical structure of hemicellulose in earlywood (EW) and latewood (LW) of two individual Japanese cedar trees (C-Boka and T-Boka) were investigated. The trees were cultivated under different growth conditions: C-Boka grew slowly in a forest, while T-Boka grew rapidly in a location rich in nutrients and sunshine. For the chemical structure of hemicellulose, arabinoglucuronoxylan (AGX) showed varied side-chain substitution rates with glucuronic acid and different molecular weights in the transition between EW and LW. In contrast, the fundamental composition of glucomannan/galactoglucomannan (GM/GGM) was relatively unchanged between EW and LW. The modification of AGX and GM/GGM from EW to LW differed between C-Boka and T-Boka and might be influenced by the growth rate of the trees.

WOOD RESEARCH Volume 68, Number 3, 2023
Sarah Augustina, Wahyu Dwianto, Muhammad Adly Rahandi Lubis, Ratih Damayanti, Danang Sudarwoko Adi, Jamaludin Malik, Imam Wahyudi, Wayan Darmawan, Philippe Gerardin, Sari Delviana Marbun, and Hiroshi Isoda

Effect of Anatomical Structure on Dimensional Stability of Low Molecular Weight Phenol-Formaldehyde Impregnated Wood

This research deals with low molecular weight-phenol formaldehyde (LMW–PF) impregnation on sepetir (Sindora spp), nyatoh (Palaquium spp.), and pisang putih (Mezzettia spp.) woods to determine the effect of different anatomical structure on weight percent gain and dimensional stability improvement. The wood samples were impregnated using LMW–PF solutions with 7, 8, 9, 10, and 11% of concentrations (w/w), vacuum-pressured (–98 kPa, 15 min, 350 kPa, 4 h), and re-immersed in 80°C for 3 h. According to the findings, LMW–PF impregnation reduced coefficient of swelling by 9.64–29.95%, and increased anti-swelling efficiency by 12.24–29.91%. Additionally, the water absorption and thickness swelling reduced by 2.43–38.75% and 15.94–34.21%, respectively, indicating the improvement of dimensional stability. Microscopy and NIR analysis revealed the presence and reaction of LMW–PF within porous wood matrix. The effect of diverse anatomical structures caused complexity on LMW–PF impregnation. Sepetir-treated wood with fewer anatomical barriers resulted in better dimensional stability improvement than others.

WOOD RESEARCH Volume 68, Number 3, 2023
Mehmet Gunes and Mustafa Altunok

Investigation of Bending Strength of Tannin Impregnated Wooden Beams after Heat Treatment

In this study, the changes in bending strength were investigated by applying heat-treatment to laminated beams modified with acorn tannin to improve the mechanical properties of wooden load-bearing structural members. For this purpose, acorn tannin was impregnated on samples prepared from Scotch pine (Pinus sylvestris L.), oak (Quercus petraea L.), and chestnut (Castanea sativa Mill.) woods. Heat treatment was applied to the samples impregnated with acorn tannin at 150ºC for 3 hours. Untreated, heat-treated, and tannin-modified samples were conditioned until they reached constant weight at 20ºC at 65% relative humidity (RH), 40ºC at 35% RH, and 10ºC at 50% RH. Bending resistance tests were applied to the elements that are conditioned in outdoor conditions according to ISO 13061-3. The results of bilateral interaction between tree species and treatment type were compared, the highest bending strength increase was found in Scotch pine samples by 5% compared to control samples.

WOOD RESEARCH Volume 68, Number 3, 2023
Chun-Won Kang, Kazuharu Hashitsume, EUN-SUK JANG, and Haradhan Kolya

Relationship between Wood Anatomical Features and Surface Roughness Characteristics

This study aimed to investigate the relationship between surface roughness and anatomical features of wood in 15 different species of boards. Surface roughness was measured parallel and perpendicular to the wood grain using a surface profilometer, and anatomical features such as pore size and distribution were analyzed using microscopic techniques. The results showed that surface roughness perpendicular to the grain direction was consistently higher than that parallel to the grain direction for all wood samples. This difference in roughness was correlated with pore size and density. It shows that the larger pores and lower density lead to higher roughness perpendicular to the grain. The study also found that traditional hand planning methods (push and pull) produced a smooth surface finish, with no statistical differences in roughness.

WOOD RESEARCH Volume 68, Number 3, 2023
Qiaofang Zhou, Dongdong Liang, Aokai Cheng, Xianju Wang, and Dengyun Tu

Effects of Pressing Temperature and Compression Ratio on Density Distribution and Hardness of Surface Densified Poplar Wood

Process parameters play an important role in wood surface densification. In this study, the poplar (Populus tomentosa Carr.) wood was heated on one side at 100℃, 150℃ and 180℃, and compressed in the radial direction with the speed of 10 mm/min. The initial thickness of the wood samples were 30 mm, 26 mm and 23 mm, and they were all compressed to 20 mm and resulting in three different compression ratios: 33.3%, 23.1% and 13.0%. When the surface densification completed, the density distribution and hardness of the densified and un-treated samples were measured and analyzed. Results show that the compressing temperature mainly decided the formation of the density distribution curve and the peak density increased with the increasing temperature; as the compression ratio increased, the peak density increased and the thickness of the densified zone broadened; the surface hardness was highly correlated with the density distribution which was affected by temperature and compression ratio, and as the peak density increased and the thickness of the densified broadened the hardness increased accordingly. Therefore, by optimizing the process parameters such as the compressing temperature and compression ratio could generate a targeted density distribution which has the desired hardness.

WOOD RESEARCH Volume 68, Number 3, 2023
Dimitrina S. Kiryakova, Antoniya S. Ilieva, and Neli А. Simeonova

Effect of Water Absorption on the Mechanical Properties of Silane-Treated Wood Flour Polypropylene Composites

The behavior of the wood flour-polypropylene composites prepared with various contents of untreated and silane-treated wood flour by immersion in water was studied, as well as the effect of the water absorbed by the samples on their mechanical properties. The highest degree of water absorption was observed for the composites containing 30 – 50 mass% alkali pre-treated wood flour. For the materials with 50 mass% untreated, silane-treated and alkali pre-treated wood flour, the water absorption measured was 8.76%, 7.84% and 13.91%, respectively, after 15 days immersion in water. The value of the thickness swelling calculated for the samples prepared with 50 mass% silane-treated wood flour – polypropylene was the lowest – 1.29%. It was proved that the absorption of water molecules results in change of the tensile profile of the thermoplastic polypropylene composites filled with hygroscopic filler.

WOOD RESEARCH Volume 68, Number 3, 2023
Chunmei Yang, Zanbin Zhu, Tongbin Liu, Bo Xue, Wen Qu, and Tingting Wang

Determination of Urea-Formaldehyde Resin Content in Poplar Fiber Based on Hyperspectral Techniques

In this experiment, poplar fibers containing 0%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 25% and 30% of urea-formaldehyde resin were prepared. A model for the detection of urea-formaldehyde resin content in poplar fibers was established by the hyperspectral near-infrared imaging system combined with relevant algorithms. The spectral images of poplar fibers containing different contents of urea-formaldehyde (UF) resin were measured separately using hyperspectral imager. The results of four preprocessing methods, namely mean centering (MC), multiple scattering correction (MSC), standard normal variables (SNV) and first-order derivative (1-Der) were analyzed, and the optimal preprocessing method was selected as SNV. The band combinations with the highest correlation with the urea-formaldehyde resin content were compared and analyzed with the full-band model to establish the partial least squares regression (PLSR) model. The experimental results show that the hyperspectral imaging system combined with the corresponding algorithm can achieve rapid detection of UF resin content in poplar fibers, and the results of this study provide technical support and theoretical reference for determination of resin content in ultra-thin fiberboard production. The method is an innovative model for the determination of UF resin in wood fibers.

WOOD RESEARCH Volume 68, Number 3, 2023
Sumanta Das, Miroslav Gašparík, Anil Kumar Sethy, Peter Niemz, Rastislav Lagaňa, Tomáš Kytka, Martin Sviták, and Gourav Kamboj

Suitability of Aspen (Populus Tremula L.) for Cross-Laminated Timber (CLT)

Cross-laminated timber (CLT) CLT is an excellent material for building and high load-bearing structural applications, but its fabrication and use are limited to softwood only. The suitability of aspen (Populus tremula L) wood for manufacturing CLT was assessed by using two adhesives, one-component polyurethane (1C-PUR) and melamine adhesive (ME). Physical properties like water absorption (WA), thickness swelling (TS), delamination, and mechanical properties like bond shear strength, bending modulus of elasticity, bending strength, and rolling shear strength were evaluated to examine its suitability. Compared to ME-bonded CLT, 1C-PUR bonded CLT panels displayed superior physical characteristics, with 70% passing the delamination test. CLT panels bonded with 1C-PUR adhesive also have better mechanical properties than ME-bonded CLT. CLT panels experienced three types of bending failure: rolling shear, delamination, and tension. Aspen CLT has similar or higher mechanical properties than traditional softwoods, making it suitable for CLT manufacturing.

WOOD RESEARCH Volume 68, Number 3, 2023
HARUNA SEIDU, RÓBERT NÉMETH, Francis Wilson Owusu, James Korang, Appiah-Kubi Emmanuel, James Kudjo Govina, Fath Alrhman A.A Younis, and Safia Ibrahim

Mechanical Properties of PF and MUF Bonded Juvenile Hybrid Eucalyptus Plywoods Produced in Ghana

To obtain the mechanical properties of plywood produced from six yearold hybrid Eucalyptus in Ghana was the objective of this research. The samples for the experiment were prepared and tested according to GS EN 326-1, GS EN 310, GS EN 314-1, and GS EN 314 -2. The data obtained were analysed using the factorial ANOVA analysis. The mean results obtained for the various treatments were MOE (6520 – 7638 N/mm2), MOR (53.29 – 60.56 N/mm2, shear strength (2.47 – 5.51 N/mm2), failure (72 -90%) and density (725 – 748 kg/m3). The orientation of the surface veneer caused variations among treatments whiles the adhesives PF and MUF largely did not cause any variations among treatments. This study has proven that it is possible to produce sufficiently strong and resistant plywood from the juvenile wood of eucalyptus.

WOOD RESEARCH Volume 68, Number 3, 2023
Dénes Horváth, Sándor Fehér, and Mátyás Báder

The Potential of Producing High Added Value Structural Timber from Lamellae Waste. Classification and Visual Grading

This study is the continuation of the first part (Horváth et al. 2023), in which density, bending strength and modulus of elasticity of 100 oak lamellae generated as small-sized production waste were investigated. In this part of the study series, the classification of our sample set is carried out according to the EN 338. A visual pre-grading is presented, to remove the worst specimens and achieve a better final result and a standardized visual grading is also shown. Our results are compared with literature values of clear specimens as well. Amount of 80% of the specimens were found to be suitable for further structural use. The total sample set is classified in strength class D35 (average density 712.6±72.5 kg/m3; average MoRadj 65.4±16.2 MPa; average MoEadj 13.4±3.1 GPa), while the visually pre-graded part with better average test results is classified in strength class D45. Industrial wood residues contain a sufficiently high proportion of elements for further processing, so that after sorting it can be used as raw material for glued-laminated load-bearing timber.

WOOD RESEARCH Volume 68, Number 3, 2023
Peter Rantuch, Jozef Martinka, Tomáš Štefko, Igor Wachter, and Mária Zuzana Bednáriková

Characterization of the Burning of Oriented Strand Boards Exposed to Flame

Since the methods based on the interaction of a relatively low intensity flame on the lignocellulose sample surface often do not allow measuring the heat release rate (HRR), a procedure using oxygen consumption calorimetry was proposed. The method was applied to OSB samples with dimensions of 320 mm x 140 mm x 25 mm placed in a vertical position. During the measurement, in addition to the HRR, the production of smoke, which was significant after stopping the burner, was also monitored. The average net value of HRR at burner outputs of 3 kW, 4 kW and 5 kW was 2.339 kW and the smoke specific extinction area was in the range of 10.88 m2.kg-1 and 13.19 m2.kg-1.

WOOD RESEARCH Volume 68, Number 3, 2023
Tamás Király and Zsolt Karácsonyi

Fracture Testing of Edge-Notched Timber Beams with Different Growth Ring Orientations

The purpose of this research is to test Norway spruce specimens with different growth ring orientations weakened by edge-notch until failure. In the experiments the specimens were subjected to 3-point bending, tension and compression tests. In addition, failure mode during loading is investigated using a high-resolution camera. Based on the measurement results the correlation between latewood ratio, ultimate force, ultimate elongation/deflection, calculated moduli, growth ring orientation and diameter of the growth ring at the edge-notch were obtained. Based on the population data of the three tests conducted, only one parameter pair, namely the ratio of latewood to calculated modulus, influences the measurement results to almost the same extent. The other parameter pairs show different values and correlations.

WOOD RESEARCH Volume 68, Number 3, 2023
Uğur Aras

Possibility of Using Crude and Expanded Vermiculite in Cement-Bonded Particleboard Production

The aim of this study is to investigate the effect of using vermiculite on the thermal, physical and mechanical properties of cement-bonded particleboards. For this purpose, single-layer cementitious particle boards with a final density of 1200 kg/m3 and a size of 550 x 550 x 10 mm were produced using 2 type vermiculites (crude and expanded) at three different ratios (5%, 10% and 15%). The produced boards were examined in terms of thermal (TGA/DTG), physical (moisture content, density, water absorption and thickness swelling), mechanical (modulus of rupture, modulus of elasticity, internal bond strength and screw withdrawal resistance) properties. According to the TGA results, using both types of vermiculite caused an increase in cement hydration products in the boards and increased the thermal resistance. While the use of vermiculite did not significant effect on the density and moisture content of the boards, it increased the dimensional stability of the boards. The values of modulus of rupture and modulus of elasticity increased when the low amount of vermiculite was added. However, with the use of vermiculite in the boards, there was a decrease in the internal bond strength and screw withdrawal resistance values in general. All boards produced using vermiculite met the values specified in EN standards.

WOOD RESEARCH Volume 68, Number 3, 2023
Marcelo Moreira Da Costa, Rodrigo Fraga De Almeida, Maria Tereza Angeletti Nunes, Ricardo De Carvalho Bittencourt, Larissa Soares Silva, Cassiano Rodrigues De Oliveira, Ana Márcia Macedo Ladeira Carvalho, and Sebastião Renato Valverde

Comparative Study between the Chemi-Thermo Mechanical Pulping from Eucalyptus spp., Bambusa vulgaris and Dendrocalamus asper

In this study, pulps of the species Bambusa vulgaris and Dendrocalamus asper were produced through the chemi-thermo mechanical pulping process, which had their morphological and mechanical properties compared with industrially produced Eucalyptus spp. pulp. The total yields of the pulping processes were 71.3 and 77.0% for the species Bambusa vulgaris and Dendrocalamus asper, respectively. The higher basic density presented by the biomass of the Dendrocalamus asper species can lead to a high productivity. Both bamboo species led to pulps with higher mechanical properties compared to industrial Eucalyptus spp. pulp. The pulp of Bambusa vulgaris stood out in terms of mechanical properties, reaching a higher level of mechanical properties with less energy spent on refining, being indicated for the production of papers for applications where high tensile index is required. Dendrocalamus asper pulp proved to be more suitable for applications, in which high liquid absorption capacity is required due to its high bulk.

WOOD RESEARCH Volume 68, Number 3, 2023
Fatimah Ayu Warahapsari, GANIS LUKMANDARU, Masendra, and Andrian Fernandes

Short notes: A Chemotaxonomic Study of the Resins from Three Dipterocarp Species (Shorea macrophylla, Shorea pinanga, and Shorea hopeifolia)

A chemotaxonomic study on the resins of Shorea macrophylla, Shorea pinanga, and Shorea hopeifolia was conducted. The dichloromethane extracts were separated into neutral and acidic fractions and then analyzed using GC-MS. The neutral fraction analysis revealed that spathulenol, caryophyllene oxide, aromadendrene oxide, and isoaromadendrene epoxide were the major constituents in all three species. Furthermore, the main compound in the neutral fraction of Shorea hopeifolia was isocaryophyllene which was undetected in the other two species. The major constituent of the acidic fraction of the three species was hexadecanoic acid, while pentadecanoic acid was the major constituent in the acidic fraction of Shorea pinanga and Shorea hopeifolia. Therefore, the presence of sesquiterpenes as well as fatty acids in S. macrophylla, S. pinanga, and S. hopeifolia was discovered to be a marker for identifying the genus Shorea.

WOOD RESEARCH Volume 68, Number 3, 2023
Boháček Štefan, Pažitný Andrej, and Slámová Stela

Optimisation of energy consumption in paper production. Review

This article examines the current state of research on energy efficiency in the paper industry, focusing on the key strategies, technologies, and best practices for improving energy efficiency and reducing greenhouse gas emissions. The review covers a range of topics, including energy management systems, process optimisation, cogeneration, waste heat recovery, and renewable energy sources. Overall, the energy efficiency improvements can significantly reduce energy costs and carbon emissions in the paper industry. Still, there is a need for more comprehensive and integrated approaches that consider the entire value chain of paper production.