WOOD RESEARCH Volume 65, Number 5, 2020
Zhongxi Zhou, Chungui Du, Huilong Yu, Xiaoling Yao, and Qiuli Huang

Promotion effect of nano-SiO2 on hygroscopicity, leaching resistance and thermal stability of bamboo strips treated by nitrogen-phosphorus-boron fire retardants

Whereas hygroscopicity an leaching resistance often have a bad influence on performance of fire-retardants, in this work, nano-SiO2 sol was added to different nitrogen-phosphorus-boron fire retardants to make four new compounds to impregnate bamboo strips, named: (1) ammonium dihydrogen phosphate + disodium octaborate tetrahydrate (AD), (2) ammonium dihydrogen phosphate + disodium octaborate tetrahydrate + nano-SiO2 sol (ADS), (3) ammonium dihydrogen phosphate + boric acid (AB), and (4) ammonium dihydrogen phosphate + boric acid + nano-SiO2 sol (ABS). After that, the hygroscopicity, leaching resistance and thermal stability were studied by scanning electron microscopy (SEM), energy dispersive X-Ray spectroscopy (EDX), thermogravimetric (TG) and fourier-transform infrared spectrometer (FTIR), and the optimal compound fire retardant is ABS. The results show that the addition of nano-SiO2 sol can not only reduce the hygroscopicity of fire-retardant bamboo strips effectively, but also improve its leaching resistance. The results also indicate that compared with non-fire-retardant bamboo strips, the thermal stability of bamboo strips treated with AB and ABS was improved significantly, and there was no significant difference between AB and ABS.

WOOD RESEARCH Volume 65, Number 5, 2020
Lukáš Velebil and Petr Kuklík

Strength and stiffness of mechanically jointed CLT panels loaded by shear in plane

This article is focused on research into the racking strength and stiffness of mechanically jointed cross laminated timber shear walls considering the influence of fasteners between the layers of boards on the stiffness of panels. The work includes an experimental analysis and analytical model. The experimental analysis included tests of the shear wall panels, tests of the specimens to determine the stiffness at the joint of the layers and material tests. The analytical model based on the component method allows the determination of the racking strength and horizontal displacement of the shear wall in dependence on the number of layers and the number of fasteners in the joint of layers, parameters of the anchorage to the substructure and applied external load. The outputs of the numerical model and the results of the experiments agree relatively well. The largest relative displacement error is 18%.

WOOD RESEARCH Volume 65, Number 5, 2020
Tawich Pulngern, Kasan Chanto, Waraluk Pansuwan, and Woraparn Pattaraumpornsak

Effect of lamina thickness on flexural performance and creep behavior of douglas fir glued laminated timber beam

This research presents the effects of lamina thickness on flexural and creep performances of glulam timber. Flexural test results indicated that nonlinear load-displacement curve could be defined as both exponential and power functions. Lamina thickness was not affected to nonlinear curve, especially at initial linear relationship. Slightly different of 2.92% for nonlinear function parameters was obtained. For flexural creep test due to three levels of sustained load for 1,000 hours, only secondary creep stage behaviors without delamination were observed for all glulam timbers while average relative creep was 1.66. Effect of lamina thickness was also not found for creep performance. Finally, creep models have been developed including Bailey-Norton, adjusted Pickel, simplified Pickel, and Dorn models and found that Bailey-Norton and the adjusted Pickel models gave a good correlation with experiment and were the suitable models which could be used to predict long-term flexural creep behavior for various stress levels.

WOOD RESEARCH Volume 65, Number 5, 2020
Ana Laura Soler Cunha Buzo, Sergio Augusto Mello Silva, Vinicius Borges De Moura Aquino, Eduardo Chahud, Luiz Antonio Melgaço Nunes Branco, Diego Henrique De Almeida, André Luis Christoforo, João Paulo Boff Almeida, and Francisco Antonio Rocco Lahr

Addition of sugarcane bagasse for the production of particleboards bonded with urea-formaldehyde and polyurethane resins

The present study deals with a production of pine particleboards using the sugarcane bagasse content and using castor-oil based bicomponent polyurethane resin and urea-formaldehyde resin. The influence of incorporation of sugarcane bagasse on the physical and mechanical properties of the composites was evaluated. The particleboards were produced according Brazilian standard ABNT NBR 14810, but performance requirements have been analyzed using Brazilian and international standards, as well. Treatment 2, using PU resin, were considered the best treatment using pine residue and sugarcane bagasse, presenting physical properties values 60% lower and mechanical properties 65% higher on average when compared with panel without sugarcane bagasse, indicating the good performance of sugarcane incorporation and the possibility of its use on commercial purpose for thermal and acoustic insulation. The addition of sugarcane bagasse improved physical and mechanical properties of particleboards when compared to panels manufactured from pine wood particles only. Statistical analysis indicated that moisture content and bagasse content were significant, enhancing properties when compared with reference treatments.

WOOD RESEARCH Volume 65, Number 5, 2020
Liyan Ma, Lina Wang, Xiaojun Ma, and JIANING LI

In situ hydrothermal synthesis of MnO2 nanowires/wood derived activated carbon hollow fibers composite and its application in supercapacitor

Composite electrode material composed of MnO2 nanowires and wood-derived activated carbon hollow fibres (Mn@ACHFs) was successfully fabricated by in situ hydrothermal method. In this work, MnO2 nanowires were developed by adjusting the mass ratio of potassium permanganate and wood activated carbon hollow fibres (ACHF). The ACHF with hierarchical porous structure served not only as the support for the growth of MnO2 particles, but also as the electric double layer capacitance for the composite electrode. The Mn@ACHFs exhibited an outstanding specific capacitance of 420 F.g-1 at 1 A.g-1 and cycle stability with 99.7% capacitance retention after 5000 cycles at 5 A.g-1. Electrochemical characteristics of the prepared composites are attributed to the synergetic effect of the double layer capacitance of the hierarchical porous ACHF and the layered structure of MnO2, which can efficiently enhance the conductivity and stability of the electrodes.

WOOD RESEARCH Volume 65, Number 5, 2020
Mahdi Santoso, Ragil Widyorini, Tibertius Agus Prayitno, Joko Sulistyo, and Noor Hamidah

Effect of pressing temperatures on bonding properties of sucrose-citric acid for nipa palm fronds particleboard

The objective of this study was to investigate the properties of nipa front particleboard bonded using the combination of sucrose and citric acid, and the effect of different pressing temperature. The results showed that the adding citric acid to sucrose and increasing pressing temperature increased the physical and mechanical properties of the nipa fronds particleboards. FTIR analysis results indicated that the peak intensity of C=O ester group and C–O–C hemiacetal group increased and the hydroxyl OH groups decreased with increasing pressing temperature and addition of citric acid, which indicated that crosslinking between sucrose and citric acid occurred. TG-DTA analysis confirm that increasing pressing temperature and addition of citric acid to sucrose increasing thermal stability of nipa fronds particleboards, which is suspected caused by the polycondensation reaction between sucrose and citric acid.

WOOD RESEARCH Volume 65, Number 5, 2020
Yihang Zhou, Kai Wang, Xueqi Chen, and Dongbo Hu

Alterations in the anatomy and chemical structure of archaeological wood from a tomb of northern china due to different fungal rots

This paper aims to identify the decay types and investigate the chemical alterations in the three types of fungal decayed archaeological wood from Dongshan Han Tomb M6 (ca. 200-100 B.C.) in Taiyuan City, China. Microscopy, FT-IR, 13C NMR and XPS were adopted to reveal the features of the samples. The results show that from the microscopic and chemical perspectives, these samples are consistent with the characteristics of brown-rot, white-rot and soft-rot. However, all the samples show the accumulation of carboxylic acids or carboxylate salts from extensive oxidation of lignin, which were not observed in artificial fungal decayed wood. Moreover, different fungal decay types and pH values of the samples corresponding to the alternative forms of carboxylic acid or carboxylate salt are considered to be influenced by combined factors, such as the position in the tomb, groundwater level, moisture content, oxygen availability, etc. This study may provide a reference for the deterioration and conservation of fungal decayed wooden artifacts in the tomb of northern China where alkaline loess is the main soil type.

WOOD RESEARCH Volume 65, Number 5, 2020
Łukasz Warguła and Mateusz Kukla

Determination of maximum torque during carpentry waste comminution

In order to elaborate design guidelines for developing efficient and possibly most energy saving mills for comminuting carpentry, OSB and MDF waste, there have been performed some tests aimed at torque demand on the working unit of the machinery participating in that process. The tests were carried out on a cylindrical wood chipper. There were indicated the maximum, minimum and average values of the torque, indispensable for the comminution of boards with defined geometric sizes (5 – 50 mm wide ) and thickness (3 – 28 mm). The value of torque required in the comminution of carpentry waste increases with growing cross section, and the torque vs. cross section relation is approximately linear. The presented values may constitute not only a set of input data indispensable for modeling the power which is necessary for the comminution process, but they can also enable the validation of the existing cutting models with a single cylinder cutter.

WOOD RESEARCH Volume 65, Number 5, 2020
Muhammed Said Fidan, Sekip Sadiye Yasar, Osman Komut, and Mehmet Yasar

A study on noise levels of machinery used in lumber industry enterprises

The aim of this study is to help to create a healthier environment by measuring the noise levels in the furniture and lumber sectors of forest products industry. In this study, noise measurement for approximately 3 min has been conducted in 4 measurement spots in the side of the machinery, in the factory entrance and in full and empty state for each machinery; from 3 different chosen spots in enterprises producing lumber. Measurements have been recorded as 720, from each machine as 36 measurements, with the condition to be recorded every 5 sec for 3 min. For this purpose, noise measurements have been carried out in 17 workplaces producing lumber and results have been compared statistically. As a result of the obtained findings, it is understood that the noise levels of thickness machinery don’t exceed the value for the upper limit stated in the regulations. However, vertical wood band sawmill and band saw machines have been observed to go over this limit. Besides, some factors of planning and multi slitting machine don’t exceed this limit, some of them exceed. As a result, it has been conducted that when noise levels of machinery used in the lumber industry enterprises exceed the upper limit stated in the regulations, they can pose a serious threat to human health.

WOOD RESEARCH Volume 65, Number 5, 2020
Liping Yu, Meifen Tian, Lifen Li, Zhigang Wu, Sicheng Chen, Jie Chen, and Xuedong Xi

Study of nano colloidal silica sol based protectant on the prevention of masson pine

In this study, wood protectants were prepared by using manganese chloride, potassium carbonate, borax and nano colloidal silica sol. Effects of the wood protectants on decay resistance, anti-mold property and fire resistance of Pinus massoniana Lamb. were discussed. The results indicated that the optimal formula of the protectant was composed of 20% colloidal silica sol and 8% modifier (manganese chloride + potassium carbonate + borax). Under this formula, the protectant had good permeability and fluidity, accompanied with synergistic effect between colloidal silica sol and modifier. Pinus massoniana Lamb. treated by the protectant with this formula showed good decay resistance, and its mass loss rates after corrosion by Gloeophyllum trabeum and Coriolus versicolor were respectively about 21% and 19%, lower than those of the control group. This indicated that the preferred samples reached I-level decay resistance according to Chinese Forestry Industrial Standards LY/T 1283-2011. Moreover, Pinus massoniana Lamb. under this formula had good anti-mold property, manifested by 100% resistance to Aspergillus niger V. Tiegh and Trichoderma viride Pers. ex Fr. The treated Pinus massoniana Lamb. also showed good fire resistance with the oxygen indexes before and after leaching respectively at 20.45% and 13.64%, higher than those of the control group. It was concluded that the formulated protectant of this research had not only multiple functions of one dose, but also comprehensive resistances to decay, mold and fire, as well as strong leaching resistance.

WOOD RESEARCH Volume 65, Number 5, 2020
Zill-E-Huma Aftab, Shakil Ahmed, Arusa Aftab, Iffat Siddique, Muzammil Aftab, Zubaida Yousaf, and Farman Ahmed Chaudhry

Wood degrading mushrooms potentially strong towards laccase biosynthesis in Pakistan

In present study, Pleurotus ostreatus, Ganoderma lucidum, Ganoderma ahmadii, Ganoderma applanatum, Ganoderma australe, Ganoderma colossus, Ganoderma flexipes, Ganoderma resinaceum, Ganoderma tornatum, Trametes hirsutus, Trametes proteus, Trametes pubescens, Trametes tephroleucus, Trametes versicolor, Trametes insularis, Fomes fomentarius, Fomes scruposus, Fomitopsis semitostus, Fomes lividus, Fomes linteus, Phellinus allardii, Phellinus badius, Phellinus callimorphus, Phellinus caryophylli, Phellinus pini, Phellinus torulosus, Poria ravenalae, Poria versipora, Poria paradoxa, Poria latemarginata, Heterobasidion insulare, Schizophyllum commune, Schizophyllum radiatum, Daldinia sp., Xylaria sp., were collected, isolated, identified and then screened qualitatively for their laccase activity. Among all the collected and tested fungi Pleurotus ostreatus 008 and 016, Ganoderma lucidum 101,102 and 104 were highly efficient in terms of laccase production. The potent strains were further subjected to Quantitative laccase bioassay for partial purification and characterization of industrially important enzyme.

WOOD RESEARCH Volume 65, Number 5, 2020
Wenbo Xie, Yewei Ding, Zheng Wang, Zizhen Gao, Tongyue Zhang, Yuhao Zhou, Yuhang He, and Xiuling Huang

Testing and analysis of hemlock cross laminated timber

In this paper, the three-layer Canadian hemlock CLT panel was designed to test the elastic modulus and bending strength of CLT specimens by four-point bending method. The interlaminar shear of CLT specimens was tested by short-span three-point bending method. Strength, the shear strength and wood breaking rate of the CLT specimens were tested by the stair shear method. At the same time, the failure mode of the CLT board was analyzed. The main conclusions indicate that the test values of bending and shear performance of Hemlock CLT can meet the relevant grade requirements of standard ANSI APA PRG320: 2012. During the bending process, the CLT specimen firstly exhibits a rolling shear failure of vertical layer after reaching the non-elastic deformation phase. After that, the damage extends gradually to the interface layer. The final failure mode is shear failure of interface layer or tensile failure of parallel layer. The interlaminar shear performance is partly relevant to the converted timber performance of parallel layer of CLT under the short-span three-point bending test conditions. The position of interlaminar shear failures is concentrated near support points of specimens and the position is generally located at the interface between parallel and vertical layers, inclining to the parallel ones. CLT at Grade 1 has significantly higher interlaminar shear strength than CLT at Grade 2. There is a certain variability in the test results of wood failure rate of CLT. The overall mechanical properties of the hemlock specification material and the hemlock CLT can meet the relevant grade requirements of Standard ANSI APA PRG320: 2012. The above can provide reference for the optimization design and application work of CLT heavy-duty timber structure.

WOOD RESEARCH Volume 65, Number 5, 2020
Elena Nikolaevna Koptelova, Natalia Alekseevna Kutakova, Sergey Ivanovich Tretjakov, Anna Viktorovna Faleva, Evgeny Razumov, and Štefan Barcík

Extraction of betulin from the birch bark balance at pulp and paper production

The technical bark was used to obtain betulin; the one which is a barking of birch balance at pulp and paper production. The bark was prepared by grinding it on a crusher of abrasive action and fractionating, thus, the main fractions were obtained: less than 1 mm (35.4%), from 3 to 4.5 mm (31.5%). The bark was separated during the grinding process, the bark prevails in the coarse fraction, while bast is found in the fine fraction. For comparison, model samples of various sizes of birch bark were obtained by hand cutting. Chemical processing of bark fractions and model birch bark samples were carried out by the use of super-high frequencies (SHF) extraction with ethyl alcohol. Raw betulin was settled from extracts. The yield of extractive substances and raw betulin was 12.1-21.9% and 5.1-16.7% from absolutely dry raw materials; the maximum yield was from a coarse fraction of the bark or from model samples with smaller particle sizes. The authors studied the kinetics of the yield of extractive substances depending on the duration of SHF-extraction for bark fractions and birch bark samples. The optimal duration of the extraction for bark fractions is 10 min, and for birch bark is 15 min. The quantitative content was determined by the high performance liquid chromatography (HPLC) method for the obtained samples of betulin raw material. The total content of triterpenoids in the samples is about 80%, the betulin share is between 70.3 – 72.1%, from the absolutely dry substances of the extract. Coarse fraction of the bark contains more of the main component as compared to other fractions. It is advisable to use the fine fraction of the bark as a source of phenolic substances.

WOOD RESEARCH Volume 65, Number 5, 2020
HENRICH LÜBKE, VLADIMÍR IHNÁT, Kuňa Vladimír, and Balberčák Jozef

A multi-stage cascade use of wood composite boards

A multi-stage cascade model was implemented on wood composite boards in four stages: particle boards → 100% recycling → middle density fibreboards → 100% recycling → paper liner. Preparation of composite boards bonded with urea-formaldehyde resin was simulated on plates 400 x 400 mm and final fiber was pulped using semi-production refiners to create the conditions closed to real. Mass changes and losses were observed during a whole simulated life process.
Results confirmed a deterioration of mechanical strength of recycled particle boards, the flexural strength in 13% and internal bond strength in 34% and slight increasing of the modulus of elasticity in static bending in 1.3%. Termomechanical pulping for the fineness in range 13°SR-24°SR (Schopper-Riegler) was chosen as appropriate for a fibrous board preparation from recycled chips, but their mechanical properties are at lowest levels compared to the requirements of standards. A low quality paper liner containing OCC, to improve its strength, was produced in the last stage of cascading.

WOOD RESEARCH Volume 65, Number 5, 2020
Ignacio J. Diaz-Maroto and María Consuelo Diaz-Maroto

Cork from Quercus suber L.: Forest certification system for sustainable management of cork oak forests

Cork is the outer bark of the cork oak (Quercus suber L.), it is a secondary protection structure of tree, and its chemical composition is different from that of other lignocellulosic materials, as wood, agricultural, or forestry wastes. The best cork sheets are used to manufacture natural cork stoppers, vital in the aging process of “great” wines. It is a Mediterranean species covering an overall area of 2,139,942 hectares; Portugal and Spain countries where it occupies a larger area.
This paper was developed to assess the possibility of implementing a system of payment for ecosystem services and/or a certification of forest management for small stands of cork oak privately owned areas of less than 25 hectares. The process is leaded by the Regional Groups of Forest Certification and Chain of Custody, main regional institutions. The system used is the Programme for the Endorsement of Forest Certification (PEFC). As specified by the multifunctional forestry applied in these ecosystems, its main use is the production of natural cork stoppers for the quality aging wines. The cork oak forests are living representatives of sustainability and a driving force of sustainable development.