Articles

WOOD RESEARCH Volume 61, Number 6, 2016
Juraj Gigac, MONIKA STANKOVSKÁ, and Pažitný Andrej

Influence of the coating formulations and base papers on inkjet printability

At the coating were used two substrates, commercial base paper and base paper produced in pilot experimental paper machine. The printing quality varied at both base papers. The coating colours contain commercial silica and precipitated calcium carbonate pigments. As a binder was used polyvinyl alcohol and cationic starch combined with high-cationic polymer SMAI 1000. Colour gamut significantly improved when the inkjet ink contact angle decreased below 14° independently of the base paper. The order of coating colours effect on the base papers was similar. Application of silica pigment in the coating colour provided papers with the largest inkjet ink wetting, the best colour gamut area, print sharpness and smoothness. By using of polyvinyl alcohol, a high colour gamut area was reached but it resulted in a markedly low print sharpness in comparison with cationic starch. Coating of base paper produced in pilot experimental paper machine introduces papers with higher colour gamut and also print sharpness.

WOOD RESEARCH Volume 61, Number 6, 2016
Birol Üner, Kenan Kömbeci, and Mehmet Akgül

The utilization of tomato stalk in fiber production: NAOH and CAO pulping process

This study was conducted to explore the utilization of tomato stalk in the paper industry. Fiber morphology of the material was determined according to standard test methods and average fiber length was found to be 980 μm and the width of the fiber was 15 μm. As a result, slenderness ratio was resolved to be around 60. This was considered to be comparable fiber with the most of the hardwood species. Tomato stalks were cooked with soda and lime in a separate process. Screened pulp yield was determined to be 35-45 %. Soda pulp of tomato stalks showed good mechanical properties when temperature raised to 135ºC and low alkali concentration (10 %) and lime pulps showed properties as well as that soda pulp at 135ºC and high alkalinity ratio (30 %).

WOOD RESEARCH Volume 61, Number 6, 2016
Adam Wójciak

Deacidification of paper with Mg(OH)2 nanoparticles: The impact of dosage on process effectiveness

The aim of the work was to analyse the influence of Mg(OH)2 nanoparticle dosage on the deacidification process, especially in relation to paper permanence. Samples of model papers were characterised by SEM-EDX and XPS methods which proved effective neutralisation. The influence of the suspension concentration was evaluated on cellulose DP and on the optical properties after the paper thermal ageing process. Generally, the protective effect of deacidification increased along with an increased dosage of the magnesium hydroxide nanoparticles in artificially acidified paper samples and in papers covered with iron gall ink.

WOOD RESEARCH Volume 61, Number 6, 2016
Bo-Han Xu, Yan-Hua Zhao, Jing-Hua Guo, and Ya-Xun Wang

Fracture toughnesses of interlaminar fracture of glued-laminated timber

Critical strain energy release rate GC and stress intensity factor KC are both defined as fracture toughness, and they can be converted to one another through an equivalent elastic modulus for wood fracture. Whereas the equivalent elastic modulus for interlaminar fracture toughness of glued-laminated timber (glulam) is kept unknown. This paper briefly presented Modes I and II interlaminar fracture toughnesses of glulam, which were obtained from double cantilever beam (DCB) and three-point bending end-notched flexure (3ENF) tests using finite element method (FEM). On the basis of Hankinson-type formula and equivalent elastic modulus of wood fracture, this study developed two empirical expressions to calculate the equivalent elastic moduli for Modes I and II interlaminar fracture of glulam.

WOOD RESEARCH Volume 61, Number 6, 2016
Onur Ülker and Erol Burdurlu

Some mechanical properties of densified and laminated Lombardy poplar (Populus nigra L.)

In this study, it was studied the effects of densification and then lamination processes on some mechanical properties of Lombardy poplar (Populus nigra L.), which is one of the low density tree species. Densification temperatures were 80, 100, 120 and 140ºC and ratios of densification were 15, 30 and 50 %. Furthermore, lamellas with a thickness of 4 mm cut from densified materials were laminated by bonding one on top of the other with urea formaldehyde (UF) and polyvinyl acetate (PVAc) adhesives. Bending, modulus of elasticity, compression and tensile tests were applied by preparing specimens from the pieces. According to test results, the most suitable temperature level was 120°C. As the ratio of densification was increased at this temperature level, increase were observed in the mechanical properties. Also, lamination provided significant increases in the mechanical values compared to laminated but undensified Lombardy poplar. Increases were observed in the mechanical properties reaching 444 % with application of densification and lamination processes.

WOOD RESEARCH Volume 61, Number 6, 2016
Xu Jiahe, Zhou Yucheng, Qi Yuhan, Hou Xiaopeng, Ge Zhedong, and Chen Yongping

A weighted filtered back projection algorithm for log CT two-dimensional and three-dimensional image reconstruction

Log computer tomography (CT) image reconstruction is the kernel of wood CT nondestructive testing (NDT) technology. In this paper, based on the logs physical properties and the X-rays propagation characteristics in solid, the X-ray wave equation inside logs is deduced. A weighted filtered back projection (FBP) algorithm for log CT image reconstruction is proposed. Four group of logs are chosen for simulations on the weighted FBP algorithm. In the twodimensional image reconstruction process, the capabilities between conventional FBP algorithm and weighted FBP algorithm are compared to verify the effectiveness of the algorithms for logs of different species. From both the image quality and data results, it can be clearly seen that the weighted FBP algorithm has good performance and advantages for image reconstruction process of log CT scan. The three-dimensional log image reconstruction is well completed, but has a big room for improvement.

WOOD RESEARCH Volume 61, Number 6, 2016
Iveta Marková, Eva Mračková, Alena Očkajová, and Juraj Ladomerský

Granulometry of selected wood dust species of dust from orbital sanders

Formation and presence of dust in the timber premises is part of the technology. Dust is generated as a byproduct based on the method of machining. The paper deals with granulometric analysis of selected samples of wood dust sessile oak (Quercus petraea Liebl.) and from deciduous multiple-pore wood there was chosen European beech (Fagus sylvatica L.) and alder (Alnus glutinosa L.) and the mixture taken directly from timber production of grinders SCM SANDYA 300RCS) for the purpose of selecting the percentages of the various fractions (0.032; 0.063; 00:08; 0.125; 0.250; 0.5; 1; 2 mm) of samples of wood dust. Wood dust samples were made using a hand orbital sander BOSCH PSS 200AC and sizing on the automatic mesh vibratory sieve machine Retsch AS 200 control. The most frequent percentages of dust particles (between 50-79 %) in all samples of wood dust there were fractions of 32 and less than 32 μm (bottom). The most abundant percentage creates conditions of the risk of inhaling and respirable components contained in the fraction over 32 μm and the potential of formation of a dust-air explosive mixture. Comparison of results granulomertic fractions contribution of wood sanding dust typically processed wood in the furniture industry (beech, oak, spruce, fir, and alder) was significantly confirmed of the particle size.

WOOD RESEARCH Volume 61, Number 6, 2016
Ergün Güntekin and Tuğba Yilmaz Aydin

Prediction of bending properties for some softwood species grown in Turkey using ultrasound

Ultrasound has been used in prediction of bending properties for some important wood species grown in Turkey including Calabrian pine, Anatolian black pine, Cedar and Oriental Spruce. Sound velocities of small clear wood specimens were determined using EPOCH 650 ultrasonic flaw detector with 2.25 MHz contact longitudinal transducers at constant moisture content. Following non-destructive measurements, specimens were subjected to three point bending tests. The measured average sound velocities for species tested in L directions were ranged from 4510 to 5254 m∙s-1. Although spruce had the lowest density (425 kg∙m-3), it had the highest sound velocity. The predicted average dynamic modulus of elasticity (Edyn) values for the species tested varied from 10137 to 12856 N∙mm-2. The correlation coefficients between Edyn values and MOE values were higher than those between Edyn and MOR. Edyn values are higher than calculated MOE values. The correlation coefficient between predicted Edyn and calculated MOE values ranged from 0.81 to 0.89. The correlation coefficient between Edyn and MOR varied from 0.78 to 0.88 for the species tested. Results indicated that there was no certain relationship between the density and wave velocity except Calabrian pine which showed negative weak correlation. MOE is better indicator of MOR than Edyn as expected.

WOOD RESEARCH Volume 61, Number 6, 2016
Martin Boldiš, Miroslav Gašparík, Milan Gaff, and Daniel Ruman

Compression set of PU foam mattresses with self-clamping joints and sandwich structure

This paper deals with research on the impact of composition on compression set of the PU foam mattresses. Three type of mattress composition, with sandwich structure and self-clamping joints, were used for research. The fourth type, which contained traditional glued joint, served as a reference. During static compression of mattresses, the properties of the individual layers have been recorded or calculated, such as Young’s modulus, shear modulus and coefficient of shear friction, which were necessary for the SolidWorks simulation of the permanent deformation. The results, as well as simulations of mattress compositions, have proven that the compression set is strictly dependent on the loading time. The highest permanent deformation was recorded for mattress type A and the lowest ones for mattress type B, which had permanent deformation almost identical to that of the composition with glued joints. The last two mattress types had permanent deformation 35 % greater. It is clear from the results that the properties of selfclamping joints in upholstery can equal those of conventional glued joints. Using self-clamping joints is more advantageous in that they exclude the negative effects of glues as well as the gluing process itself.

WOOD RESEARCH Volume 61, Number 6, 2016
Kaiting Zhang, Yuxia Chen, Yong Guo, Shengquan Liu, Tingliang Guan, Na Su, and Shiliu Zhu

Research of bamboo qualitative material tactile characteristics

In this study, the semantic differential method was employed for investigating the tactile properties of bamboo qualitative material, such as bamboo integrated timber (vertical splicing plate), bamboo integrated timber (transverse splice plates), bamboo parallel strand lumber, whole bamboo unfolding plate (outer of bamboo), whole bamboo unfolding plate (remove outer of bamboo), bamboo plastic composite plate, while Liquidambar formosana and Abies fabri (Mast) were selected as contrast. Respondents rated the samples by descriptive words, such as natural, exclusive, eco-friendly, rough, inexpensive, reliable, warm, modern, snug, and solid. Moreover, statistical analysis was employed for analyzing the data. The results showed that material and tactile characteristics exhibit significant correlation. Principal component analysis yielded four attributes based on tactile perceptions. Summing up the main points of the experiment, the tactile properties of different bamboo qualitative material were obtained.

WOOD RESEARCH Volume 61, Number 6, 2016
Jin Heon Kwon and Nadir Ayrilmis

Short note. effect of hot-pressing parameters on selected properties of flakeboard

Physical and mechanical properties of flakeboards produced from radiata pine flakes under different hot-pressing conditions were investigated in this study. The flakeboard mats were hot-pressed at 2.8 MPa with two different temperatures (170 and 190°C) and three different durations (7, 10, and 15 min). At the 170°C of hot-pressing temperature, the highest bending strength was found in the flakeboards pressed for 7 min while the highest modulus of elasticity was found in the flakeboards pressed for 15 min. The highest internal bond strength was found to be 0.13 MPa for the flakeboards pressed at 190°C for 15 min. The thickness swelling and water absorption of flakeboards pressed at 190°C were lower than those of the flakeboards pressed at 170°C. The control of hot press temperature and duration appears an effective method to enhance serviceability of flakeboard.

WOOD RESEARCH Volume 61, Number 5, 2016
Chu Jie, Ma Li, and Zhong Yang

Comparison of bamboo fibers in sulfuric acid, sodium hydroxide and glycerin pretreatments

The chemical compositions and structural characterizations of bamboo samples with three pretreatments using sand bath to heat were comparatively studied with Fourier infrared spectrum (FTIR). The results showed that the holocellulose and cellulose yields increased significantly and the dilute alkali (NaOH) pretreatment performed better lignin removal rate than that of dilute acid (H2SO4) and glycerin pretreatments.Furthermore, when the same solutions were used, the compositional changes were more remarkable at 135 than at 117°C, and the similar degradation of hemicelluloses was observed for the different pretreatments. With sodium hydroxide at 135°C, compared to un-treated bamboo, cellulose increased by 14.21 % and hemicellulose decreased to 13.98 %, counting the removal of lignin to 20.29 %. In which, the bamboo expressed the betterdelignification with sand bath and higher temperature and combinations with other methods of glycerin pretreatment should be evaluated in the future work.

WOOD RESEARCH Volume 61, Number 5, 2016
Ignacio Javier Diaz-Maroto and Sylvain Tahir

Analysis of physical properties of wood in three species of Galician oaks for the manufacture of wine barrels Part i: Wood infradensity

The current study about physical properties of wood of Quercus robur L., Q. petraea (Matt.) Liebl., and Q. pyrenaica Willd. in Galicia (northwest of Spain) was based on the determination of proportion of sapwood, heartwood, infradensity, and porosity to understand and estimate the variation of these characteristics and/or properties in the Galician oaks. For this, it was necessary to fell several trees within the study area. In total, 45 trees were chosen in 15 different stands of provinces of Lugo and Ourense, i.e., we have obtained 45 wood slices of Quercus at 60 cm tall on the trunk of the tree, and 194 wood samples with a parallelepiped shape and dimensions of 2×2×4 cm ± 1 mm. The infradensity characterization reveals that oak wood from Galicia has a greater infradensity than French oaks, and Quercus pyrenaica has a higher infradensity than Q. robur and Q. petraea. There is a strong variation of the same based on the geographic origin, but there is almost no variation inside a plot. The global objective was to realize a detailed description on the physical properties of wood of these species for its possible use in industry cooperage. For this, the objective of this initial work was to begin with the study of wood infradensity.

WOOD RESEARCH Volume 61, Number 5, 2016
Zuzana Brezániová, Mária Fišerová, MONIKA STANKOVSKÁ, Juraj Gigac, Elena Opálená, and Jarmila Puškelová

Effect of prehydrolysis on enzymatic hydrolysis of two-stage pretreated wheat straw

The effect of water prehydrolysis conditions, which was used as the first stage of wheat straw pretreatment, on the composition of filtrates was analysed. Many of the substances that are present in the prehydrolysis filtrates are broadly used and thus they contribute to improvements in the efficiency of bioethanol production. Prehydrolysis was carried out at temperatures of 140, 160 and 180°C and times of 30, 60 and 120 min. Xylose and its oligomers were the most represented in prehydrolysis filtrates, their yields increased up to 12.1 % with increasing weight of wheat straw removed up to 28.6 %. Besides xylose and glucose, acetic acid, formic acid and the phenolic compounds were also present in the prehydrolysis filtrates. At 160 and 180°C, levulinic acid and furfural and hydroxymethylfurfural, respectively, were also present. The solid fractions of wheat straw were subjected to steam explosion under the same conditions at 200°C for 2 min. Two-stage pretreated wheat straw was subsequently enzymatically hydrolysed. The conditions of water prehydrolysis combined with steam explosion pretreatment had a significant effect on the results of enzymatic hydrolysis of wheat straw. The conversion of cellulose increased with increasing prehydrolysis temperature and time from 64.8 to 91.7 %. Similar results were observed for the conversion of xylan from 73.7 to 92.4 %. With increasing of prehydrolysis temperature and time, the amount of inhibitors in hydrolysates decreased. The recommended conditions for water prehydrolysis at two-stage pretreatment of wheat straw correspond to temperature of 160°C and time of 60 min.

WOOD RESEARCH Volume 61, Number 5, 2016
Mehmet Colak

Determination of antifungal and antibacterial activities of natural dye of pomegranate skin (Punica granatum L.) implemented on wooden materials

The demand for partially harmless dyes produced from natural sources as an alternative to synthetic dyes has been increasing. Natural dyes environment and they are attractive materials contributing to the protection of natural balance and to the reduction of aesthetic concerns of people. Yet, for natural dyes to be long-lasting and cling to the surface, they need to be used with mordant substances. In the present study, the purpose is to determine the antifungal and antibacterial activities of natural dye obtained from pomegranate skin by means of ultrasonic. Plant extract obtained through ultrasonic method was applied to oriental beech (Fagus orientalis L.) and yellow pine (Pinus sylvestris L.) wooden materials by means of dipping and ultrasonic-assisted immersion. For the analysis of the results, data obtained from the natural dye were compared with those obtained from the synthetic dye. The findings of the analysis revealed that the most effective results in terms of antifungal activities were obtained from the solutions applied to yellow pine wood. For beech samples, the natural dye yielded better results when compared to the synthetic dye. Moreover, pomegranate skin solutions were found to prevent the spread of antibacterial activities. As a result, it was concluded that pomegranate skin extract can be used as wood preservative and coloring materials by mixing with holding provider.

WOOD RESEARCH Volume 61, Number 5, 2016
Jihang Hu, Wenmiao Fan, Bin Luo, Hongwu Guo, and Li Li

Assessment of the dyeing properties of maple veneer treated by dichlorotriazine reactive dye based on fuzzy comprehensive evaluation

Effects of dye concentration, dyeing temperature and time, volume ratio, and dyeing assistant and fixing agent, fixing time on the dye-uptake and K/S were investigated with orthogonal experiments. The major factors on dye-uptake and K/S were identified using visual and variance analysis. Dye-uptake and K/S were synthetically evaluated and optimally selected with fuzzy comprehensive evaluation. Results showed that dye concentration and temperature were significantly affected by all the seven factors during dyeing process on dye-uptake and K/S. The optimal parameters for the dye effect of maple veneer were: temperature 65.0ºC, dye concentration 3.0 %, dyeing assistant 40.0 g.L-1, dyeing time 3.0 hours, fixing agent 20.0 g.L-1, fixing time 10.0 minutes, volume ratio 1:20. Additionally, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) results indicated that reactive dyes were combined with maple fiber and diffused into the wood lumen and wood ray. X-ray diffraction (XRD) results indicated the intensive of crystallinity in the dyed wood was declined due to the dichlorotriazine reactive dye. Furthermore, thermogravimetric analysis (TGA) demonstrated that the residue of dyed veneer was higher than undyed, and the temperature at maximum degradation rate of dyed and undyed veneer was different.

WOOD RESEARCH Volume 61, Number 5, 2016
Kristýna Vavrušová, David Mikolášek, Antonín Lokaj, Kristýna Klajmonová, Oldřich Sucharda, and Přemysl Pařenica

Determination of carrying capacity of steel-timber joints with steel rods glued-in parallel to grain

The issue of behavior and deformation of joints of wooden structures is an integral part of the design of timber structures in its entirety. In this article the attention is therefore devoted to joints of timber structures. For testing there were selected joints with glued-in steel rods. These joints are currently, due to the frequent requirement for invisibility of joints in structures, at the forefront of interest. The content of this paper is therefore testing of these joints and determination of their carrying capacity and describing the type of deformation under load. These tests were carried out on a pressure machine EU100 in the laboratory of the Faculty of Civil Engineering VSB-TU Ostrava. The results of the laboratory tests have been statistically evaluated and accompanied by the graphical records of deformation response to loading. Comparison of test carrying capacity results with values determined from calculation according to the current applicable European standard for design of timber structures and numerical modeling are also presented.

WOOD RESEARCH Volume 61, Number 5, 2016
Fatih Yapici, Nurettin Şenyer, and Raşit Esen

Comparision of the multiple regression, ann, and anfis models for prediction of MOe value of OSB panels

This research investigates the prediction of modulus of elasticity (MOE) properties, which is the most important properties in many applications, of the oriented strand board (OSB) produced under different conditions (pressing time, pressing pressure, pressing temperature and adhesive ratios) by multiple regression, artificial neural network (ANN) and adaptive Neurofuzzy inference system (ANFIS). Software computing techniques are now being used instead of statistical methods. It was found that the constructed ANFIS exhibited a higher performance than multiple regression and ANN for predicting MOE.Software computing techniques are very useful for precision industrial applications and, also determining which method gives the highest accurate result.

WOOD RESEARCH Volume 61, Number 5, 2016
Andrea Nasswettrová, Soňa Křivánková, Pavel Šmíra, Jan Štěpánek, Martin Friedl, and Jan Trubák

Acoustic detection of wood-destroying insects during

This thesis deals with experimental verification of hot-air preservation efficiency on wooden members of structures against larvae of wood-destroying insects, particularly against larvae of longhorn beetle Hylotrupes bajulus L. The verification of hot-air efficiency on mortality of larvae was performed within the process of hot-air preservation of a room of a building in Čeladná, Czech Republic. Parameters of hot-air preservation met the specifications of standards according to which the process is controlled. The efficiency was monitored by means of the Acoustic Pack acoustic system which recorded acoustic emissions of larvae emitted during wood ingestion. To verify the acoustic system and hot-air preservation, the samples were subject to destruction analysis after the preservation. Using a Keyence VHX-S550E digital microscope, the analysis of changes in the structure of larvae before and after the process of preservation was performed. The results showed that designed parameters of hot-air preservation lead to the mortality of larvae.

WOOD RESEARCH Volume 61, Number 5, 2016
Kuňa Vladimír, Balberčák Jozef, Elena Opálená, Pažitný Andrej, ALBERT RUSS, and Jiří Schwartz

The effect of multi-component retention systems on the properties of the paper suspensions

This study presents the influence of retention reagents and multi-component retention systems on properties of pulp suspension which is used during toilet paper production. The following relationships were evaluated: influence of retention systems on rate of pulp suspension water drainage, values of specific cationic and anionic demand, Zeta potential of fibers, WRV values of fibers and water turbidity. The best results were achieved from applying three-component retention system which consisted of micro-milled bentonite Hydrocol OT, modified cationic polyethylenimin Polymín SK and cationic polyacrylamide Percol 830. The above mentioned three-component retention system resulted in increased rate of pulp suspension drainage by 43 %, improvement of water turbidity by 50 % and decrease of specific cationic demand by 33 %. The proposed retention system resulted in improved values of WRV pulp suspensions, which led to decrease of values by about 10 %. Influence of three-component retention system resulted only in minimal decrease of Zeta potential values for fibers.