Articles

WOOD RESEARCH Volume 62, Number 2, 2017
Marija Đurković and Gradimir Danon

Comparison of measured and calculated values of cutting forces in oak wood peripheral milling

The aim of investigations was to determine whether the tested models for calculating forces in wood cutting, set up under strictly controlled laboratory conditions, can yield sufficiently accurate results for predicting wood behavior in real cutting conditions. Tests were carried out on oak wood (Quercus robur). On the basis of measured values for the required cutting power, cutting forces were calculated and used for comparison by applying the method of coefficient (Kršljak’s model) and Axelsson’s model. The analysis indicated that there is not a result, but there is similarity in the curve shape, i.e. changes in measured values are followed by corresponding changes in calculated values. It can be inferred that analyzed models are not suitable for the cutting forces quantification, but could serve for comparing different cutting modes. More accurate modeling of the cutting process requires, besides physical, wood mechanical properties as well.

WOOD RESEARCH Volume 62, Number 2, 2017
Krzysztof Szwajka and Tomasz Trzepieciński

An examination of the tool life and surface quality during drilling melamine faced chipboard

An analysis of the cutting process and tool wear during machining from metal materials has been the subject of many studies. On the other hand, the tool life when machining from wood materials has not received much attention. Optimisation of the cutting process consists of the appropriate selection of major processing parameters as the cutting depth, feed rate and cutting speed in order to ensure adequate machining accuracy at minimum cost, and appropriate process efficiency. Here, we present the results of experimental tests of wearing drills with carbide blades during processing of melamine faced chipboard (MFC). To evaluate the surface quality of the chipboard the maximum radius and area of delamination around the chipboard blind hole are adopted. These parameters are determined independently at the hole entry and exit. Statistical analysis of results using multifactor analysis of variance was carried out. The tool life of drills depends on many combinations of cutting parameters and the wear of the drill blade. In the drilling process, the value of the thrust force mainly depended on wear of tool flank and the feed rate. The cutting speed has little effect on the amount of thrust force and cutting torque.

WOOD RESEARCH Volume 62, Number 2, 2017
Aurel Lunguleasa and Cosmin Spirchez

Torrefaction of lamellar panels made of oak and spruce wood species

This paper is focused on the torrefaction of lamellar panels made of wooden species of spruce and beech, with a view to noticing the influences of the torrefaction on the physical and mechanical properties. The working method highlights the special character of the lamellar panel torrefaction as compared to other torrefied products. The obtained results emphasize that the mass losses increase with the severity of the thermal-treatment condition, where as the hygroscopicity and mechanical properties of the material simultaneously decrease. The analysis of the obtained results recommends the use of these panels in humid/moist environment.

WOOD RESEARCH Volume 62, Number 2, 2017
Aizat Ghani, Paiman Bawon, Zaidon Ashaari, Mohammad Waridwan Wahab, Lee Seng Hua, and Lum Wei Chen

Short note. Addition of propylamine as formaldehyde scavenger for urea formaldehyde-bonded particleboard

Rubberwood particleboard were produced using urea formaldehyde (UF) resin admixed with propylamine as formaldehyde scavenger. 1 % propylamine were incorporated into 8 %, 10 %, 12 %, 14 % and 16 % UF resins, respectively. The effectiveness of propylamine addition to reduce formaldehyde emission from particleboard was examined. Physical and mechanical properties were evaluated according to Japanese Industrial Standard (JIS). The results showed that addition of propylamine had reduced 33 to 65 % formaldehyde emission from particleboard made with different dosages of UF resin. However, the properties of the particleboard were adversely influenced by the addition of propylamine. Higher resin dosage (≥14 %) had counterbalanced the loss of strength and dimensional stability but accompanied by increased formaldehyde emission. As a conclusion, UF dosage of 14 % admixed with 1 % propylamine is the most ideal formulation to produce particleboard with low formaldehyde emission while maintaining the desired properties.

WOOD RESEARCH Volume 62, Number 2, 2017
Szabolcs Koman, Sandor Feher, and Andrea Vityi

Short note. Physical and mechanical properties of Paulownia tomentosa wood planted in Hungaria

The Paulownia tree (or to its well-known name Chinese empress tree; Paulownia tomentosa) is classified among the most variable wood species of the world concerning usability. Its cultivation in Hungary in form of research plantations has just started in the last decade, first of all for the investigation of energetic properties. Due to this the information related to the physicalmechanical properties of the wood was still not determined, from which aspect this study is essential. The investigated wood with an air-dry density of 0.3 g.cm-3 has shown low bending (42 MPa), compressive (22 MPa), shear (7 MPa), tensile (33 MPa) and impact strength (1.6 J.cm-2) values, based on which its wooden material properties can be compared to poplars considering tree species in the region.

WOOD RESEARCH Volume 62, Number 1, 2017
Xianwu Zhou, Yurong Wang, Li Wang, Jianxiong Lv, Rongjun Zhao, Lihong Yao, and Zhangjing Chen

Cell wall structure and mechanical properties of Salix psammophila

Salix psammophila can grow rapidly in desert and grassland areas. As an abundant bioresource, it is useful to understand its cell morphology, chemical compositions and mechanical properties. In this study, Anatomical properties of Salix psammophila in different annual rings were measured and compared. Fourier transform infrared spectroscopy and chemical titration were used to estimate cell wall chemical compositions. Moreover, mechanical properties in different annual rings were measured through nanoindentation. Fiber cell lumen diameter, fiber cell wall thickness, vessel cell lumen diameter and vessel cell wall thickness of Salix psammophila were measured to be 7.371, 2.285, 32.541 and 1.926 μm, respectively. Fiber cell lumen diameter, fiber cell wall thickness, vessel cell lumen diameter differs among the annual rings. The cellulose, hemicellulose and lignin contents of Salix psammophila were 44.43, 34.99 and 17.93 %, respectively. Both hemicellulose and lignin contents varied among the annual rings with more hemicellulose but less lignin at the annual ring closer to the pith. The modulus of elasticity (MOE) of fiber cell wall of Salix psammophila decreases from pith
to bark.

WOOD RESEARCH Volume 62, Number 1, 2017
Kelly Carla Almeida de Souza Borges, Suely de Melo Dias, Evania Galvão Mendonça, Roberto Carlos Costa Lelis, Leandro Azevedo Santos, and Sonia Regina de Souza

DNA extraction and anatomic characterization in dried heartwood from fabaceae species

The botanical family Fabaceae is the most representative in terms of diversity in Brazil, and it contains species of great importance to the domestic and international timber trade. In spite of numerous attempts to combat illegal logging, this practice is still common in Brazil, making it necessary to seek more accurate techniques for identifying wood species. This study aimed to test different protocols for extracting DNA from dried heartwood of Amburana cearensis (Fr. Allem) A. C. Smith (Cerejeira), Dypterix odorata and Peltogyne confertiflora. Additionally, these species were characterised through visual inspection and scanning electron microscopy. Five DNA extraction protocols were evaluated with six replicates. DNA amplification was conducted for the rbcL gene, a molecular marker of conserved regions in plants. It was possible to extract and amplify DNA from the dried heartwood of the tested species, with Protocol 2 (QIAGEN kit) being the most efficient.

WOOD RESEARCH Volume 62, Number 1, 2017
Birol Uner and Cagri Olgun

The effect of hardener on adhesive and fiberboard properties

Ureaformaldehyde adhesive requires hardener and about 4-6.5 pH to be cured. In this study, boric acid, boron oxide, borax, sodium perborate tetrahydrate, sodium chloride, sodium chlorite and control samples containing ammonium chloride was used as an hardener to investigate cureability of urea formaldehyde adhesive. Chemicals used as an hardener tested to demonstrate the effect on gelation time, swelling properties, MOR and MOE. Ammonium chloride, boric acid and boron oxide improved to properties when used as an hardener in single use or in mixture.

WOOD RESEARCH Volume 62, Number 1, 2017
Ladislav Reinprecht and Zuzana Vidholdová

Growth inhibition of moulds on wood surfaces in presence of nano-zinc oxide and its combinations with polyacrylate and essential oils

The paper deals about an anti-mould efficiency of nano-zinc oxide applied into wood alone (0.1%, 0.33%, 1% and 3% ZnO) or in combination with polyacrylate (5% Paraloid B-72) and essential oils (1% and 3% clove, oregano or thyme oil). Treatment of lime tree and maple samples 50×10×5 mm (L×R×T) with these chemicals was performed by one-step or two-step dipping at 20 °C/1 h. The anti-mould efficiency of used chemicals was determined by the standard STN 49 0604 – evaluating effect of chemicals against growth of four moulds (mixture of Alternaria alternata, Aspergillus niger, Penicillium brevicompactum and Chaetomium globosum) in the 7th 14th, 21st and 28th day. The anti-mould efficiency of ZnO nanoparticles was relatively poor, however, it was evidently improved in presence of clove and oregano oils, mainly in the first 7 days of the mould test.

WOOD RESEARCH Volume 62, Number 1, 2017
VLADIMÍR IHNÁT, HENRICH LÜBKE, ALBERT RUSS, and Vlastimil Borůvka

Waste agglomerated wood materials as a secondary raw material for chipboards and fibreboards. Part i. preparation and characterization of wood chips in terms of their reuse

The article describes a method of preparing particles from waste particle boards (chipboards) and oriented strand boards (OSBs). Their reuse is the main target of recycling. Method of their destruction was determined in this work. Agglomerated materials disintegrated after an initial destruction were further processed under specified conditions with regard to the material humidity, type of materials, contained adhesives and given characteristics of final particles – wood chips. Wood particles obtained were characterized by a fractional composition and amount of residual formaldehyde as an important parameter for the reuse of waste materials in production of furniture boards. New chipboards and pulp for production of middle density fiberboards (MDFs) will be provided from such defined particles.

WOOD RESEARCH Volume 62, Number 1, 2017
HUICHUAN JIANG and Feng Fu

Colorimetric and thermochromic properties of reversible thermochromic wood

To endow wood materials with a thermochromic function, an organic thermochromic agent consisting of thermochromic dye, bisphenol A (BPA) and long-chain alcohols (1-tetradecanol (TD), or 1-hexadecanol (HD)) was used as a dye to prepare reversible thermochromic wood (RTCW). The colorimetric properties, including total color difference (ΔE*ab), lightness index (L*), red-green index (a*), and yellow-blue index (b*), were investigated at different temperatures. The color change temperature range and color hysteresis of RTCW were also analyzed. The color difference unit of National Bureau of Standards (NBS) was used to determine the color change temperature range and the achromic (chromic) temperature. In the decolorization process, with the temperature increasing, the values of ΔE*ab, L* and b* of the RTCW samples increased, and the values of a* decreased, but the values of ΔE*ab, L*, a*, and b* were just opposite in the colorization process. Meanwhile, the color of the RTCW with TD or HD could repeatedly change between red and light brown (wood colore) within a color temperature range of 25-35°C or 37-49°C respectively, presenting a “color hysteresis” phenomenon over a heating (decolorization) and cooling (colorization) cycle. The achromic and chromic temperature of the RTCW samples with TD was 31°C and 25°C respectively while RTCW samples with HD was 43°C and 37°C.

WOOD RESEARCH Volume 62, Number 1, 2017
Irena Hubálková, Jakub Houška, Jan Kubíček, Pavel Mazal, Jindřich Pavliš, Josef Pohořalý, Gabriela Vačkářová, and Martin Duchoslav

Preliminary anatomical study on secondary thickening parts of endemic Dracaena cinnabari balf.fil. from the Soqotra island

The present study investigates anatomical structure of secondary thickening parts (rootstem- branch) of endemic monocot Dracaena cinnabari. The measurement of microscopic structure parameters was carried out using analytical imaging. The differences between vascular bundles were determined. The results show presence of concentric vascular bundles in all investigated plant organs. In general, the parenchyma cells cover majority of the total area (an average of 77%), much less covers xylem (an average of 19%) and phloem (an average of 4%). The results indicate that the plant body is well adapted to sub-tropical climate regimes and specific environmental conditions prevailing on the island such as limited access to soil moisture and sufficient nocturnal dew which is essential for plant growth and survival.

WOOD RESEARCH Volume 62, Number 1, 2017
Alina Samusevich, ALEŠ ZEIDLER, and Monika Vejpustková

Influence of air pollution and extreme frost on wood cell parameters at mountain spruce stands (Picea abies (L.) karst.) in the ore mountains

The aim of the research was to evaluate the potential of wood anatomy parameters as stress indicators on base of changing cell characteristics and proportion of latewood in Picea abies stands damaged by extreme climatic conditions in combination with high air pollution load during the winter 1995/96. The research was carried out in the Ore Mountains (Czech Republic), where sites were located along the gradient of forest damage. Preliminary analyses showed the decrease of lumen width, cell wall thickness and the number of tracheid in the tree rings of spruce at heavily damaged site. Significant difference was shown between sites with different damage level. Moreover the difference in reaction dynamics of earlywood and latewood parameters was recorded. The length of stands regeneration was shown to be around 3 years depending on the assessed parameter and the damage rate.

WOOD RESEARCH Volume 62, Number 1, 2017
Ilyas Deveci, Ergun Baysal, Hilmi Toker, Mehmet Yuksel, and Turkay Turkoglu

Thermal characteristics of oriental beech wood treated with some leaching resistant borates

It was aimed to investigate thermogravimetric analysis (TGA), differential-thermogravimetric (DTG), and differential-thermal analysis (DTA) of Oriental beech (Fagus orientalis L.) wood treated with some leaching resistant borates such as sodium tetraphenylborate (STPB) and phenylboronic acid (PBA). In this study; 0.25, 1.00, and 4.70 % aqueous solutions of borates were prepared. Results of the study indicated that pyrolysis occurred in three stages for STPB and PBA treated Oriental beech wood. Generally, while concentrations of the STPB and PBA increased, Ti and Tmax values of STPB and PBA treated wood specimens decreased. Residual char contents of STPB and PBA treated wood specimens for all concentrations were higher than untreated control specimen.

WOOD RESEARCH Volume 62, Number 1, 2017
Xiaolei Guo, Huiyun Wang, Qingqing Chen, and Bin Na

The dimensional stability of engineered wood f looring in heating systems

In this work, the effect of decorative veneer type, wood structure and wood shape on the dimensional stability was studied in a laboratory with a simulated heating system. Poplar/seven layer plywood engineered hardwood (structure C) or a 9 mm thick poplar substrate layer wood which contained the two veneer surface layers, structure A and structure B were used. The results indicated that whatever the structure and decorative veneer of flooring were, the dimensional stability of engineered wood flooring had a better performance in length; In width, with the same structure and decorative veneer, the dimension stability of engineered wood flooring with the veneer shape of mono-block was better than the shape of three splice; With the same decorative veneer, the dimensional stability of structure C was best, the second was structure B, and structure A was the worst; With the same structure, the dimensional stability of engineered wood flooring decorated with birch was best, the second was eastern black walnut, the third was eucalyptus, and maple was the worst. Thus, the engineered wood flooring of structure C decorated with birch with mono-block veneer was judged to be better for the dimensional stability.

WOOD RESEARCH Volume 62, Number 1, 2017
Andrea Nasswettrová, Soňa Křivánková, and Pavel Šmíra

Comparison of the results of dendrochronological measuring based on different images of a historical wood sample of silver fir (Abies alba) from the Czech republic

The aim of the paper was to compare the results of different methods of measuring the tree rings curve performed using different images of a reference sample made from a historical wooden con-struction of silver fir wood. The tree-ring curves were measured using two measurement methods: firstly manually on the traversing table using a stereo microscope with TSAPWin dendrochronolog-ical software and secondly in the LignoVision software (LV) from uploaded image files (scans, modified monographic scans and X-ray scans). Automatic image analysis was also tested in this software. Results showed that the tree-ring curves based on manual determination of printed-out photographs and scans using a stereo microscope on a traversing table and on manual determination of identical digital images in LignoVision matched to a large extent the data obtained by measuring the physical sample. The results were worse when tree-ring curves were measured from an X-ray scan, both using stereo microscope on a printed image, and using LignoVision. The automatic anal-ysis of the LignoVision software showed a high error rate. Finally, the results of measurements of individual image types and the possibilities of practical use of individual image records of dendro-chronological samples are discussed.

WOOD RESEARCH Volume 62, Number 1, 2017
Zhaolong Zhu, Xiaolei Guo, Bin Na, Xingyu Liang, Mats Ekevad, and Futang Ji

Research on cutting performance of ceramic cutting tools in milling high density fiberboard

The effect of cutting parameters and tool parameters on cutting forces and tool wear were investigated in high density fiberboard (HDF) peripheral up-milling using toughened ceramic cutting tools. The results showed that whether at low speed cutting or high speed cutting, the tangential forces Ft and normal forces Fr increased slowly with the increase of cutting length. The tangential forces Ft and normal forces Fr at low speed cutting were higher than that at high speed cutting. The tangential forces Ft and normal forces Fr decreased with the decrease of wedge angle in the same rake angle. Then, the effect of high cutting speed on the flank wear was greater than that at low cutting speed. The bigger wedge angle tools led to the serious flank wear. The main wear pattern in milling HDF consisted of pull-out of the grain, flaking, chipping and cracking, the main wear mechanism were adhesive and abrasive wear.

WOOD RESEARCH Volume 62, Number 1, 2017
Roger Moya and Carolina Tenorio

Strength and displacement under tension and compression of wood joints fastened with nails and screws for use in trusses in Costa Rica

The objective of the present study is to determine the behaviour of two typical types of fastener (nails and screws) used in trusses made of Gmelina arborea and Hieronyma alchorneoides timber. Wood joints with metal fasteners (nails and screws) and five angles (0°, 30°, 45°, 60° and 90°) were subjected to tension and compression loads in order to establish values of displacement in relation to applied loads, strength, stiffness values, mode of failure and a model for prediction of stiffness for intermediate orientations. Results indicate that the differences in loads and displacements appear among species in the compression test, whereas those differences appear among fasteners in the tension test. The results obtained for stiffness indicate that jointsofH. alchorneoides wood present the highest values. Models for prediction of stiffness for truss joints of intermediate orientations were: in compression, while for tension the model was.

WOOD RESEARCH Volume 62, Number 1, 2017
Eva Mračková and Iveta Marková

Parameters of the laboratory model terrestrial forest fire created from the needles of pine (Pinus nigra)

The work deals with the monitoring of selected parameters in the model of terrestrial forest fire, which originated in forest litter (natural challenged material). A needle of black pine (Pinus nigra) was used as a fuel. For the model there was developed forest fire apparatus – wind tunnel, which simulates terrestrial forest fire on the basic model Superior Técnico in Lisbon (Portugal). In the apparatus, there is possibility to placing a sample on the basis of changes of coniferous litter and regulate the speed of the airflow over the layer of litter. The work reviews the effects of air velocity depending on time and temperature of coniferous leaf litter on the wind tunnel and the speed of flame propagation along the coniferous litter layer. In the article, there are original work results which show a significant effect of air flow over the surface of coniferous litter on a fire and the flame propagation speed after layer of litter. Threshold limits of the flow rate of air are in the range <0.5 m.s-1, 1.0 m.s-1>, in which there is an increase in linear speed of the spread of fire of 2 to 2.5 times. Subsequently, the linear speed of spread for models of terrestrial forest fire appeared significantly comparable at air speed 1.0 cm.s-1 and 2.5 cm.s-1. But time which shows spread of fire at specified speed has been reduced by 60% from the time of fire development at a speed of 0.5cm.s-1.

WOOD RESEARCH Volume 62, Number 1, 2017
Tomasz Jelonek, Witold Pazdrowski, and Magdalena Arasimowicz-Jelonek

Correlation between the stem hydraulic conductivity rates in scots pine (Pinus sylvestris L.) and the lignin content in tracheid walls

This paper is an attempt to evaluate the lignin formation in tracheid walls within the stem circumferential area in mature Scots pine (Pinus sylvestris L.), and establish the correlation between lignin content, and diameter at breast height and hydraulic conductivity in mature pine. The independent variables included lignin content (Lc) in tracheid walls within the stem circumferential area, and pine diameter at breast height (DBH), and the dependent variable was the relative conducting surface of stems (Sa/Nmass, Eas/Nmass). Research material came from the 89-91 year old pine stand in the north of Poland. Chemical analysis included mature wood area, i.e. last ten annual rings at 1.30 m (DBH). The results show clear interdependence between the relative conductive surface (stem hydraulic conductivity), and tree diameter at breast height and lignin content in tracheid walls within the stem circumferential area. Biometric features of pines grown in fresh coniferous forest (FC) and in fresh mixed coniferous forest (FMC) conditions were functionally linked. The link between these values was clear, although it varied, and could be approximated using the linear function.