WOOD RESEARCH Volume 67, Number 5, 2022
Ziwei Wang, Xianghua Yue, Jing Li, Hankun Wang, and Genlin Tian

Research on the structure and connections of pits in different cells of moso bamboo (Phyllostachys pubescens)

The plant grows within the transportation of water and nutrients, including radial and longitudinal, but bamboo only exists pits in the radial, so it plays an irreplaceable role at this moment. This study aims at giving rise to further understanding of the biological functions of pits in bamboo. Light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied to investigate the structure and connections of bamboo pits. The results show that the arrangement of pits is significantly different, including alternate, scalariform and opposite arrangements. The presence or absence of the bordered on different cells is also displayed distinctively, these characteristics extremely affect the transportation of water and nutrients in bamboo.

WOOD RESEARCH Volume 67, Number 5, 2022
Karol Tomczak, Przemysław Mania, and Arkadiusz Tomczak

Wood density and annual ring width of pedunculate oak from stands grown on former agricultural land

The main aim of this study was to determine differences in basic density and average annual ring width of pendulate oak wood collected from trees grown on former agricultural land and on forest land, using a dimensional method. The experiment was carried out in the western part of Poland, near to Poznan, which is in the central part of the European range of pedunculate oak. In our study the average basic density was 0.528 g.cm-3, and the value for former agricultural land was lower by 0.026 g.cm-3 than that for forest land. Differences in basic density values between these two land types were statistically significant. The average annual ring width in samples collected from forest land in our study was 2.48 mm, samples from former agricultural land were characterized by wider average annual rings. The results suggest that there are significant differences in quality of wood from former agricultural land and from forest. However, from view of wood quality and applications the difference is not important.

WOOD RESEARCH Volume 67, Number 5, 2022
Renyuan Liu, Zhuliang Zeng, Quan Li, and Cenlong Hu

The effects of ACQ and water glass on the color change and decay resistance of carbonized bamboo

In this study, samples of bamboo and carbonized bamboo were impregnated with alkaline copper quaternary (ACQ) and water glass, the resulting differences in color and resistance to decay by Gloeophyllum trabeum were evaluated. The results showed that the impregnated bamboo and carbonized bamboo greatly reduced their lightness (L*). The red-green color index (a*) first decreased and then increased, while the yellow-blue color index (b*) first increased and then decreased. The total chromatic aberration (ΔE) was largest for bamboo and carbonized bamboo impregnated with ACQ and allowed to decay. Carbonized bamboo impregnated with ACQ and water glass and bamboo impregnated with ACQ reached level I (strong decay resistance). The decay resistance of bamboo and carbonized bamboo was as follows: ACQ impregnated > water glass impregnated > CK. Scanning electron microscopy further confirmed that the bamboo and carbonized bamboo were impregnated with ACQ had fewer hyphae, the maintained intact structure, and good decay resistance.

WOOD RESEARCH Volume 67, Number 5, 2022
Changlin Huang, MING LI, SAIYIN FANG, YUE ZHAO, and FEILONG MAO

Research on the effect of wood surface cracks on propagation characteristics and energy attenuation of longitudinal acoustic emission

To investigate the effect of Zelkova schneideriana surface cracks on the longitudinal wave propagation characteristics of acoustic emission (AE). Different sizes and numbers of cracks were made on the surface of the specimen, the propagation characteristics of AE longitudinal waves along wood texture direction were studied. Firstly, five regular cracks with the same length, different width, depth and equidistant distribution were fabricated on the surface of the specimen. The burst and continuous AE sources were generated by lead core breakage and signal generator, and the AE signals were acquired by 5 sensors with sampling frequency was set to 500 kHz. Then, the propagation speed of AE longitudinal wave was calculated by Time Difference of Arrival (TDOA) based on lead core breakage. Finally, the 150 kHz pulse signals of different voltage levels generated by the signal generator were used as AE sources to study the influence of cracks on the attenuation of AE longitudinal wave energy. The results showed that the AE longitudinal wave propagation speed under the crack-free specimen was 4838.7 m.s-1. However, after the regular crack was artificially made, the longitudinal wave speed reduced to a certain extent, and the relative error of the change was not more than 9%. Compared with the energy decay rate of 1.29 in the crack-free specimen, the decay rate gradually increased to 2.08 with the increase of the crack cross-sectional area.

WOOD RESEARCH Volume 67, Number 5, 2022
Xinyi Wei, Fengwen Sun, and Jie Lin

Impregnation on poplar wood with vegetable oils: Effects on physical mechanical and dimensional stability properties

In this study, vegetable oils were selected to modify poplar with vacuum-pressure impregnation technology and the optimum progress was studied. The weight percent gain (WPG), modulus of rupture (MOR), modulus of elasticity (MOE), water uptake rate (WUR), volume swelling rate (VSR) and volume shrinkage rate (VSR’) were evaluated. The results showed that the dimensional stability, physical and mechanical properties of treated wood were significantly improved. Scanning electron microscopy (SEM) observations revealed that castor oil was inserted into the interior of the wood through the pores. Vegetable oil modification (castor oil) decreased the intensities of hydroxyl, cellulose and hemicellulose specific peak in the Fourier transform infrared spectroscopy (FT-IR) results. The Fourier transform infrared spectroscopy (FT-IR) results showed that castor oil treatment decreased the intensities of hydroxyl, cellulose and hemicellulose specific peak. Ultimately, the optimum process of castor oil treatment was impregnation pressure 1.8 MPa, time 1.0 h and temperature 85°C based on the range and variance analysis.

WOOD RESEARCH Volume 67, Number 5, 2022
Vasiliki Kamperidou, Izabela Ratajczak, Waldemar Perdoch, and Bartłomiej Mazela

Impact of thermal modification combined with silicon compounds treatment on wood structure

In the present study silicon containing formulations were investigated for their applicability in solid wood modification. Black pine sapwood was thermally modified at 180oC and 200oC (3, 5 and 7 hours) and afterwards, an additional chemical treatment with silicon containing systems (N-2-aminoethyl-3-aminopropyltrimethoxysilane) followed, in an attempt to invigorate hydrophobicity and durability of wood. Infrared spectroscopy (FTIR) was used to examine the formation of new bonds in the treated materials and atomic absorption spectrometry (AAS) to measure the silane concentration. The results showed a high reactivity between thermally modified wood and organosilicon compounds. The presence of bands representing vibrations of the Si–O–CH3 group in IR spectra of modified wood and after extraction confirms the stable character of the formed bonds between the hydroxyl group of wood and the methoxy groups of organosilanes. Furthermore, reactivity between wood and AE-APTMOS and alkyd resin solution was confirmed by the AAS results. Alkyd resin caused a higher concentration of silica in wood mass, which increases as the thermal treatment temperature increases. The organosilicon compounds caused a much higher resistance to water washout, revealing permanent binding of silanes to wood mass.

WOOD RESEARCH Volume 67, Number 5, 2022
Matheus Viana De Souza, Pedro Henrique Da Silva Cazella, Sérgio Augusto Mello Da Silva, Felipe Reis Rodrigues, Marjorie Perosso Herradon, Fabíola Medeiros Da Costa, Márcia Regina De Moura Aouada, Fauze Ahmad Aouada, Herisson Ferreira dos Santos, Edna Moura Pinto, Victor Almeida De Araujo, André Luis Christoforo, and Roberto Vasconcelos Pinheiro

Comparative study of particleboards with Hevea brasiliensis waste from different production and moisture configurations

After the production cycle of latex, Hevea brasiliensis trees become residual living plants for this activity, although their woody trunks are still potentially subject to industrial utilization. Bio-composites derived from rubberwood particles were manufactured using two different configurations as a strategy to examine the potential of this species with respect to mechanical behavior. Homogeneous panels were developed from particles at the saturation condition, and heterogeneous panels were obtained from dry particles conditioned at 12% moisture content. Both examples were heat-pressed and glued with castor oil-based polyurethane resin. Density,short-term water absorption and thickness swelling, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile were evaluated. Panels derived from rubberwood particles proved to be viable according to the technical standards.

WOOD RESEARCH Volume 67, Number 5, 2022
Jakub Kawalerczyk, Dorota Dziurka, and Radosław Mirski

The effect of a phenol-formaldehyde adhesive reinforcement with nanocellulose on the pressing parameters of plywood

Research on improving the reactivity of phenol-formaldehyde (PF) resin and the possibility of lowering the pressing parameters of wood-based materials manufactured with its participation are still progressing. Due to a number of favorable properties, nanocellulose (NCC) is gaining more and more popularity as a modifier of wood adhesives. Therefore, the objective of the study was to assess the possible reduction of plywood pressing parameters due to the reinforcement of PF resin with NCC. Based on the bonding quality results it was found that there is a possibility to reduce pressing time by 25% and pressing temperature by 7%. Moreover, the outcomes of mechanical properties (modulus of elasticity and bending strength) of manufactured plywood indicate that theoretically it could be possible to decrease the pressing parameters even more. However, the shear strength of the glue joints was considered to be a limiting factor for further reduction. The results of delamination test show that plywood bonded with phenolic resin have no tendency to delaminate. Thus, it can be concluded that NCC can be used as a modifier for PF resin which can contribute to the reduction of pressing time and pressing temperature during the plywood manufacturing process.

WOOD RESEARCH Volume 67, Number 5, 2022
Kang Chiang Liew and Yu Feng Tan

Densification and effect of compression ratio on mechanical properties of CLT from low-density timber

The mechanical properties of CLT manufactured from densified low-density planted timber, Paraserianthes falcataria were studied in relation to changes in the area of pores for under densification. Conditioned laminas (MC ≤ 15%) underwent two-stage densification using hot-press machine at 105oC, 6 MPa, for 10 min each, with press released for 1 min 40 sec in between the stages, before cooling (< 100oC) to reduce immediate springback. The laminas with thickness 8 mm, 10 mm, and 15 mm were produced using metal stoppers and further manufactured into three-layered CLT of 24 mm, 30 mm, and 45 mm thick. 20 mm undensified laminas with 60 mm CLT as the control. Results shows that modulus of elasticity (MOE), modulus of rupture (MOR), and compression parallel to grain have improved significantly and showed negative correlation with area of pores, except for compression perpendicular to grain.

WOOD RESEARCH Volume 67, Number 5, 2022
Gang Zhu, HUI LI, Kunyong Kang, Xupeng Zhang, and Shuduan Deng

Influence of vacuum impregnation pressures on the nanomechanical characteristics and photocatalytic performance of nano TIO2-furfuryl alcohol/balsa wood-based composites

In this work, a nano TiO2-FA/balsa wood-based composites were successfully fabricated by mechanical stirring assisted vacuum impregnation method, and the influence of different impregnation pressures on the microstructure, nanomechanical characteristics and photocatalytic performance of obtained composites were investigated. Results show that the nano TiO2-FA compound modifier was impregnated in the tracheid and attached to the wood cell walls. SEM revealed that the size of TiO2 nanoparticles grow larger as the impregnation pressure increases, and the presence of TiO2 globules with some areas agglomerated on the wood cell wall surface. Compared with the unmodified wood, the elastic modulus of cell walls for nano TiO2-FA/balsa wood composites prepared under 0.45 MPa significantly increased by 160.5%, and the hardness improved from 0.36 ± 0.04 GPa to 0.84 ± 0.08 GPa. Furthermore, the UV-Vis showed that the composite exhibited a high removal rate of methylene blue (10 mg.L-1), up to 88.74% within 240 min.

WOOD RESEARCH Volume 67, Number 5, 2022
Uğur Aras, Sefa Durmaz, Süleyman Kuştaş, and Hülya Kalaycioğlu

Influence of pumice powder on some properties of phenol-formaldehyde bonded particleboards

In this study, pumice powder as a volcanic aggregate was added in the particleboards’ production. The effect of various ratios of pumice powder (10%, 20%, 30%, and 40%) on physical, mechanical, thermal and fire resistance properties was investigated. Pumice powder did not significantly affect particleboards’ water absorption and thickness swelling values. However, the mechanical properties were significantly affected with raising pumice powder content. The modulus of rupture and modulus of elasticity decreased up to 46% and 45%, respectively. There was also a decrease in the internal bond strength up to 42%. Conversely, pumice powder improved the thermal degradation temperatures. The onset temperatures increased with increasing pumice powder content above 300°C. Similarly, the pumice powder improved the fire resistance of particleboards up to 7% compared to control samples.

WOOD RESEARCH Volume 67, Number 5, 2022
ARIF NIRSATMANTO, SRI SUNARTI, Dwi Kartikaningtyas, Betty Rahma Handayani, Teguh Setyaji, Surip, Sugeng Pudjiono, NOOR KHOMSAH KARTIKAWATI, Teddy Kardiansyah, Krisdianto, Dian Anggraini Indrawan, Rohmah Pari, Mindoro Razoki, Albertus Bambang Herdyantara, Sri Nugroho Marsoem, and Fanny Hidayati

Evaluation of the characteristics of Eucalyptus pellita and acacia hybrid superior clones selected from breeding program in Indonesia as materials for pulp and papermaking

This study evaluates the characteristics of superior clones of Eucalyptus pellita and Acacia hybrid (Acacia mangium × A. auriculiformis) aged six years selected from a breeding program in Indonesia as materials for pulp and papermaking. Height, diameter, and wood density differed significantly between species and among the clones, with respective mean values 21.6 m, 12.57 cm, and 657 kg.m-3 for E. pellita and 19.5 m, 24.83 cm, and 567 kg.m-3 for Acacia hybrid. Most fiber morphologies were significantly different between species. Cellulose and lignin differed significantly only among Acacia hybrid clones. The mean value of screened pulp yield Acacia hybrid (52.50%) was higher than that of E. pellita (50.31%). Kappa number and brightness were significantly different between species and among E. pellita clones. Some correlations of growth and wood properties showed a better relationship to pulp properties. Handsheet properties varied between species, and some clones showed an outstanding one.

WOOD RESEARCH Volume 67, Number 5, 2022
Hong Shuang Du, Chengyuan Li, and Chun Won Kang

Measuring the electric resistance of air drying thick red pine and larch timber

The objective of this study was to evaluate the moisture profile and drying period of air drying the red pine and Japanese larch timbers with the cross section of 14.0 cm × 14.0 cm and 16.5 cm × 16.5 cm by measuring the electric resistance of the wood. The drying curves determined by measuring electric resistance and by oven-dried method were nearly identical at last drying stage, and had almost same moisture profiles and same drying period after the end of air drying. Therefore, the drying curve determined by measuring electric resistance can be used to predict the drying period and moisture profile of air drying the red pine and Japanese larch timbers with large cross sections.

WOOD RESEARCH Volume 67, Number 5, 2022
Yanwen Zhang, Zixuan Wang, Zhihu Sun, and Jianping Huang

A deep learning program for predicting sap flow of Larix olgensis

Plant sap flow is crucial to understanding plant transpiration, plant hydraulic functioning and physiological properties. In this study, a method for predicting trunk sap flow of Larix olgensis using deep learning was proposed. The method is based on the combined use of Long-short term memory network (LSTM) and transformer model, noted as LSTM-transformer model. The experimental results show that the proposed method provides more accurate prediction quality in terms of correlation coefficient (R2), root mean square error (RMSE) and mean absolute error (MAE), compared to the state of the art forecast methods such as BP, DNN, LSTM, and transformer models.

WOOD RESEARCH Volume 67, Number 5, 2022
EUN-SUK JANG and CHUN-WON KANG

Short notes: Can the physical properties of wood samples be predicted from photographs displayed on a monitor?

This study focused on evaluating the physical properties of wood from photographs displayed on a monitor. Sample photos of 475 hardwoods and their physical information were collected from a wood database. R, G, and B values were extracted from the wood photos using color picker software. Statistical techniques such as Pearson’s correlation coefficient and multiple regression analysis were applied to investigate relationships between wood color and physical properties. From results of Pearson’s correlation coefficient, R, G, and B values were most affected by specific gravity. In a multiple regression analysis, tree size, specific gravity, and modulus of rupture (MOR) were significant in the positive (+) direction by color (R, G, and B). On the other hand, modulus of elasticity (MOE) was significant in the negative (-) direction at the 1% level by color. The specific gravity of wood had the most significant effect on R, G, and B values in multiple regression analysis. In conclusion, the color and specific gravity of wood were related closely. Additionally, it is possible to predict the physical properties of wood from the R, G, and B values of a wood sample photograph displayed on a monitor. These results could provide useful information for wood researchers as well as wood exporters and importers.