Articles

WOOD RESEARCH Volume 63, Number 4, 2018
Partson Tinarwo, Temesgen Zewotir, and Delia North

Pre-hydrolysis pulping process optimization with multiple response surface modelling

Three properties of dissolving pulp namely lignin, viscosity and the α-cellulose were investigated. A laboratory experiment for the dissolving wood pulping process was conducted on nine Eucalyptus genotypes: Edunnii, Esmithii, Egrandis, Macarthurii, Emearnsii, Enitens, GCG438, GUA380 and GUW962. Repeated measurements were taken at each of the six processing stages for the changes in lignin, viscosity and the α-cellulose. A response surface approach was used to select the best genotype for each property and further application of desirability analysis to identify the genotype that simultaneously gives the best results for the three properties. The predictive models and associated statistical tests proved that all the nine genotypes were capable of producing the optimal results (>95.55% α-cellulose) although a few were at the thresholds of the feasible region. The optimisation process also revealed that the genotype Emearnsii possesses the most desirable properties for the α-96 cellulose product output and Enitens consistently produces results within the desired range. The use of simultaneous desirability functions indicated that the overall product quality characteristics for lignin, viscosity and the α-cellulose can be improved by steadily excluding the most resistant genotypes to lignin reduction, especially Edunnii and Esmithii.

WOOD RESEARCH Volume 63, Number 4, 2018
Mária Fišerová, Elena Opálená, Juraj Gigac, and MONIKA STANKOVSKÁ

Oxidative and reductive bleaching of deinked pulp

Deinked pulps for hygienic paper production were bleached with hydrogen peroxide and sodium dithionite in single and two-stage bleaching. The brightness gain of high brightness deinked pulp in the peroxide stage was 5.7% ISO and of low brightness 4.4% ISO. In sodium dithionite stage, the brightness gain of high brightness deinked pulp was 4.0% ISO and of low brightness deinked pulp 3.8% ISO. The two-stage oxidative-reductive bleaching sequence resulted in an increase of brightness by 9.7% ISO for high brightness deinked pulp and by 9.1% ISO for low brightness deinked pulp. Brightness gain in the two-stage reductive-oxidative bleaching sequence was 6.7% ISO for high brightness deinked pulp and 5.6% ISO for low brightness deinked pulp. The coordinate b* value and yellowness of deinked pulps decreased in sodium dithionite bleaching stage more than in hydrogen peroxide stage. The two-stage oxidative-reductive bleaching sequence is more preferred than reductive-oxidative sequence regardless of the fibre composition. The tensile index and the tensile energy absorption index of deinked pulps slightly decreased after single-stage and two-stage bleaching sequences, their reduction in the peroxide stage was greater than in the dithionite stage. The fibre strength and fibre length characteristics of deinked pulps decreased after bleaching, while fibre bonding ability increased. The water absorption and bulk softness increased after bleaching, the increase was higher after peroxide stage than dithionite stage.

WOOD RESEARCH Volume 63, Number 4, 2018
Wang Yanming, Chen Zhongjia, Yuan Xiangyue, and Yu Guosheng

Influence of die temperature and moisture content on the densification of bamboo powder using die heating method

Residues of agriculture and forestry are usually exploited as feedstock within pellet production for energy producing applications. Some variables such as moisture content and die temperature strongly influence this process. Bamboo powder was used as the experimental material to produce high quality pellet fuel in this paper. A series of experiments involving pellet production were conducted in different die temperatures and at different moisture contents by a newly-developed pellet extruder using a die heating production method. Unit density and densification pressure were tested with four levels of moisture contents (5, 10, 15 and 20%) at five levels of temperatures (40, 80, 120, 160 and 200°C). The surface quality of the pellets was investigated 6 months after the pellets had been produced. The optimum moisture content is around 10% and a suitable die temperature is 160°C to 200°C when producing bamboo pellets.

WOOD RESEARCH Volume 63, Number 4, 2018
Mohammad Mehdi Ramezanpoor Maraghi, Asghar Tabei, and Mostafa Madanipoor

Effect of board density, resin percentage and pressing temprature on particleboard properties made from mixing of poplar wood slab, citrus branches and twigs of beech

In this study, construction conditions of homogenous particleboard manufactured from mixing of poplar wood (Populus alba) slab, citrus branches and beech (Fagus orientalis) twigs have been investigated. The density of particleboard at three levels of 0.65, 0.7 and 0.75 g.cm-3, the amounts of resin at two levels of 9 and 11% and the amounts of pressing temperature at two levels of 160 and 170° C were considered. Increasing the density from 0.65 to 0.75 led to an increase in MOR, MOE and IB. By increasing the density, water absorption of particleboard decreased but its thickness swelling increased. By increasing the resin percentage the mechanical properties of particleboard improved, although this improvement was not statistically significant. Furthermore, by increasing the resin percentage the dimensional stability of particleboard improved partially. Not only did increasing the pressing temperature have any significant effect on the improving of mechanical properties of the particleboard, but also it has even led to a decrease in IB. Increasing the pressing temperature reduced the water absorption of particleboard in the short term (2 hours) while this increase led to a further increase in the thickness swelling of particleboard.

WOOD RESEARCH Volume 63, Number 4, 2018
Miroslav Sedlecký, Monika Sarvašová Kvietková, Richard Kminiak, and Lukáš Kaplan

Medium-density f iberboard and edge-glued panel after edge milling – surface waviness after machining with different parameters measured by contact and contactless method

This article deals with the quality of the milled surface of board edges. The quality is evaluated using the Wa (mean arithmetic deviation of the surface waviness). The Wa was measured by two methods (contact and contactless). Form Talysurf 50 Intra was used for the contact method, and the LEXT 3D measuring laser microscope OLS4100 was used for the contactless method. The variable factors whose effect on the resulting waviness was determined were the machined material, milling cutters, cutting speed and feed rate. The boards used were medium-density fiberboard, medium-density fiberboard with single-sided lamination and spruce edge-glued panel. Three different cutters were used for the milling, all of which were made of sintered carbide, and one of them was coated (CrTiN). The cutting speeds were 20, 30, 40 and 60 m.s-1, and the feed rates were 4, 8 and 11 m.min-1. All the above-mentioned factors as well as their mutual interaction had an effect on the waviness. There was no significant difference between the two methods for determining the waviness. In terms of waviness, both methods are interchangeable.

WOOD RESEARCH Volume 63, Number 4, 2018
Chenah May and Amrani Moussa

Chemical and structural analysis of lignocellulosic biomass of Ampelodesmos mauritanicus (diss) and Stipa tenacissima

Chemical composition, anatomical characteristics and cell wall structure of Ampelodesmos mauritanicus (Diss) and Stipa tenacissima (Esparto grass) fibers were analyzed. The results reveal the % (W/W) holocellulose content of Diss and Esparto grass was found to be 54.39 % and 51.8 %, respectively. Esparto grass had the greatest % (W/W) lignin content of 32.2 % while Diss had the last lignin content of 24.95 %. Estimation of %( W/W) extractives contents in Diss and Esparto-grass were observed to be 12.03 % and 13.5 % in that order. According to XRD data, Diss showed, as expected, a lower crystallinity index (CI) 52.5 % when compared to Esparto grass samples 55.2 %. The results of the thermal decomposition of natural fibers are shifted to higher temperatures with increasing the cellulose crystallinity. Based on the results of the chemical composition of Diss and Esparto grass, it was confirmed that straw is rich in cellulosic fibers and, therefore, a valuable raw material for the paper and manufacture industry.

WOOD RESEARCH Volume 63, Number 4, 2018
Ekrem Durmaz, Saim Ates, Laboni Ahsan, Zhibin He, and Yonghao Ni

Characterization of microfibrillarcellulose (MFC) obtained from corn stalk, sunflower stalk, reed and sesame husk

Microfibrillar cellulose (MFC) samples from different agricultural resources and their wastes were characterized and compared in this study. MFCs were prepared from corn stalk, sunflower stalk, reed and sesame husk by two different methods. Hydrochloric acid (HCl) was used in Method 1, while formic acid (CH2O2) and sulphuric acid (H2SO4) were used in Method 2. SEM, FTIR, XRD and TGA analyses were conducted to determine the morphological, physical and thermal properties of the MFCs. The widths of the MFCs varied between 2.35 μm – 7.96 μm depending on the treatment methods and the raw materials. The crystallinity index of the lignocellulose increased after the chemical treatment, and the highest crystallinity index was found to be 82.0% for the sesame husk treated by Method 2. FTIR results indicate the presence of cellulose (~1640 cm-1), hemicellulose (1740 cm-1), lignin (1510 cm-1) and the other components in the MFCs. The TGA results show that the decomposition temperatures for the treated samples were higher than those for the untreated samples, indicating that the chemical treatments increased the thermal stability of the MFCs. As a consequence, it was seen that agricultural resources and their wastes can be an effective raw material in production of MFCs.

WOOD RESEARCH Volume 63, Number 4, 2018
Qian Wan, Ge Ge Wang, Ya Chi Zhang, Sha Sha Song, Ben Hua Fei, and Xiao He Li

Cognitve processing torword traditional and new chinese style furniture evidence from eye-tracking technology

Eye-tracking technology was shown to have the ability to indicate human’s cognitive preferences toward objects. Using eye-tracking technology to study the cognitive preferences on different Chinese furniture style may have the potential to promote the furniture design from a novel perspective. Experiment was designed to test the differences of eye movement index (total fixation time, average fixation counts and average pupil diameter) within variables of gender, major and furniture styles. Participants were asked to observe two sets of different styles of Chinese furniture pictures on computer screen. Significant differences of total fixation time and average fixation counts were found between different furniture styles (p<0.01), gender (p<0.001), but not in major (p>0.05). Significant difference was also found in average pupil diameter in different furniture styles (p<0.01) and gender (p<0.01).Subjects’ fixation time stayed longer on new Chinese style furniture pictures than traditional furniture pictures. The results indicated that compared to traditional Chinese style furniture, people tend to take more interest in the new Chinese style furniture. Gender as a factor had a significant influence on the cognitive processing towards the viewing of pictures of the Chinese style furniture. Meanwhile, subjects paid more attention to the decorative details on the furniture, implying appropriate design and decoration may improve people’s interest to the furniture.

WOOD RESEARCH Volume 63, Number 3, 2018
Ján Iždinský, Ladislav Reinprecht, and Erik Nosáľ

Antibacterial efficiency of silver and zinc-oxide nanoparticles in acrylate coating for surface treatment of wooden composites

The paper deals with antibacterial effect of silver and zinc-oxide nanoparticles in acrylic coatings applied at treatment of commercial wooden composites – particleboard and medium density fibreboard. The silver nanoparticles usually better suppressed the activity of the Gramnegative bacterium Escherichia coli and the Gram-positive bacterium Staphylococcus aureus already at lower concentrations (0.04 – 0.2 mg Ag/100 g of coating) as the zinc-oxide nanoparticles used in 100-times higher concentrations (4 – 20 mg ZnO/100 g of coating). Both types of applied nanoparticles at higher concentrations had a more apparent efficiency against E. coli comparing to S. aureus.

WOOD RESEARCH Volume 63, Number 3, 2018
Zhongxi Zhou, Xiaoling Yao, Chungui Du, Huilong Yu, Qiuli Huang, and Hongzhi Liu

Effect of hygroscopicity of fire retardant on hygroscopicity of fire retardant bamboo chips

This paper presents a study on the effect of hygroscopicity of fire retardant on the hygroscopicity of fire retardant materials (bamboo chips). The results showed that the hygroscopicity of fire retardant and fire retardant bamboo chips increased with increasing fire retardant concentration, and the suitable range of fire retardant concentration is 20- 30 %; the hygroscopicity of fire retardant and fire retardant bamboo chips increased with the increasing of drug loading rate of fire retardant bamboo chips, and the suitable drug loading rate is 10.2 %; the hygroscopicity of fire retardant bamboo chips increased with the increase of the hygroscopicity of fire retardant, and the hygroscopicity of fire retardant bamboo chips is smaller when treated with the fire retardant whose water absorption rate less than 18 %.

WOOD RESEARCH Volume 63, Number 3, 2018
Mátyás Báder and RÓBERT NÉMETH

The effect of the relaxation time on the mechanical properties of longitudinally compressed wood

Longitudinal compression makes natural wood easier to bend. The relaxation after compression results in much improved bending properties. During a bending test, the maximum deflection increases with the relaxation time, while the needed force to reach the same deflection decreases, similarly to the modulus of elasticity (MoE). The modulus of rupture (MoR) of the compressed wood does not change considerably compared to the untreated wood, except at the long-time relaxed samples. The ideal relaxation time is 1 minute. After that the change of the important properties slows down. Of course with special demands, the relaxation time can be also very long. In this case the process leads to a wood sample with pronounced flexible properties. Samples were left to rest between normal circumstances for 1 day, but this resting period did not have a significant effect on its mechanical properties.

WOOD RESEARCH Volume 63, Number 3, 2018
Xi Enhua

Visual simulation on dynamic accumulation of the differentiating xylem cells

This study describes the dynamic accumulation of xylem cells of the fast-growing Populus×euramericana cv. ‘74 /76’ during the growth phase by the methods of microscopy analysis and computer simulation technology. In order to show a more intuitive accumulation and dynamic variation process of cells in different periods, the computer simulation software was used to simulate the accumulation process of cambium and xylem cells according to the data of the accumulation and anatomical characteristics. The dynamic accumulation process of the xylem cells was visually displayed by the computational simulation technology during the active period.

WOOD RESEARCH Volume 63, Number 3, 2018
Niken Subekti, Priyantini Widiyaningrum, Tsuyoshi Yoshimura, and Fidia Fibriana

The strength and termite resistance characteristics of fiberboards produced from the renewable bamboo biomass

This study investigated the physical, chemical, and termite resistance characteristics of fiberboard made from the trunk fiber of five bamboo species (Giganto chloaapus, Gigantochloa atroviolacea, Giganto chloaatter, Dendrocalamus asper, and Bambusa vulgaris) and its suitability as a construction material. Five types of fiberboard with a target density of 0.8 g. cm-3 were prepared by using a hot-pressing system at a temperature of 180°C for 15 minutes. Fiberboards were examined for the bonding strength, lignin content, and morphological characteristics. Termite resistance characteristic of fiberboards was performed by three-week laboratory feeding trials against Coptotermes formosanus Shiraki and Incistermes minor Hagenas described in Japanese International Standard (JIS) K. 1571. The results showed that the strongest bonding characteristic was B. vulgarisfiberboard, followed by G. apus, G. atroviolacea, and G. atter. The highest lignin content presented in G. atter (29.23%), followed by G. atroviolacea (28.78%), D. asper (26.60%), G. apus (26.48%), and B. vulgaris (23.87%). The lowest weight loss of bamboo fiberboard after termites’ assay was D.asper (7%). In conclusion, the fiberboard made from the fiber of bamboo trunk waste hasthepotency as a promising building material. However, alltypes of bamboo fiberboard would require additional protection for applicationin the area with a high number of termite nests.

WOOD RESEARCH Volume 63, Number 3, 2018
Yihang Zhou, Kai Wang, Dongbo Hu, Li Guan, and Hao Wu

Degradation features of archaeological wood surface to deep inside a case study on wooden boards of marquis of haihun’s outer coffin

Although researches have been carried on the bio-chemical deterioration of archaeological wood, still the degradation of archaeological wood is so complicated to fully understand. One essential question is how archaeological wood of large volume would degrade from surface to deep inside and why. The recently unearthed outer coffin of Marquis of Haihun, buried for over 1800 years, gave us a great opportunity to investigate this question. The degradation features were analyzed with methods of optical microscopy, Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), viscosimetry, and determination of physical properties of wood. The results, including the microstructures of wood fibers, wood components, degree of polymerization and crystallinity of cellulose, and shrinkage of wood, unanimously show that the sapwood of the board is worst degraded, the surface layer of the heartwood is degraded to a higher extent than the inner part, and it tends to degrade more easily along the axial direction.

WOOD RESEARCH Volume 63, Number 3, 2018
VLADIMÍR IHNÁT, HENRICH LÜBKE, ALBERT RUSS, Pažitný Andrej, and Vlastimil Borůvka

Waste agglomerated wood materials as a secondary raw material for chipboards and f ibreboards Part II. Preparation and characterisation of wood f ibres in terms of their reuse

The paper describes a process for the preparation of fibre from waste wood particleboards (PB), oriented strand chipboard (OSB) and medium density fibreboard (MDF). The purpose of recycling of agglomerated wood materials is to reuse them for the production of fibrous materials. The agglomerated materials disintegrated after the initial destruction were further processed under the specified conditions with respect to the moisture content, their type, adhesive used, and properties of final particles – wood chips. The obtained wood particles were characterized by the fractional composition of chips. The resulting chips were mechanically defibred with subsequent characterization of fiber obtained for its reuse in the manufacture of MDF. A quantity of formaldehyde released into the water when cooking waste MDF and PB was set up depending on the cooking time. Residual level of formaldehyde is the main chemical load that determines the amount of waste material that can be reused for production of new panels based on ureaformaldehyde adhesives.

WOOD RESEARCH Volume 63, Number 3, 2018
Mehmet Yeniocak, Osman Goktas, Ertan Ozen, Mehmet Colak, and Mehmet Ugurlu

Determination of leaching features of wood surfaces colored by eco-friendly red beetroot (Beta vulgaris) extract

The aim of this study to develop an eco-friendly wood stain and to determine the adsorption and desorption on surfaces. In this context; plant dyestuff was extracted from the red beetroot by using ultrasonic assisted method and applied to wood blocks of Turkish oriental beech, Scots pine, oak, and walnut with immersion (classic) and ultrasonic-assisted immersion methods. As mordants, ferrous sulphate, aluminum sulphate, copper sulphate, and vinegar were chosen. In the study, the effect of such parameters as the medium pH (3, 7 and 9), temperature (22°C and 40°C), velocity of agitation (10 and 30 rpm) in leaching was investigated. As a result of experiments; red beetroot extracts performed good desorption, vinegar and copper sulphate were reduced the best desorption on surfaces. Ultrasonic-assisted method was not affect the leaching performance positively, but general leaching results showed that red beetroot can be used for wood surface stain and they can be alternative to chemical dyes.

WOOD RESEARCH Volume 63, Number 3, 2018
Hong Wei, Xiaolei Guo, Zhaolong Zhu, Pingxiang Cao, Baojin Wang, and Mats Ekevad

Analysis of cutting performance in high density fiberboard milling by ceramic cutting tools

In order to study the cutting performance of TiC reinforced Al2O3 ceramic cutting tools in milling high density fiberboard, the effects of cutting parameter on the cutting forces, tool wear and cutting quality were investigated. Under the condition of same average chip thickness, feed per tooth and geometry angles, firstly, the change rate of maximum cutting forces were higher than that of average cutting forces at two different cutting speeds, and the cutting forces at high speed cutting was less than that at low speed cutting. Secondly, the flank wear at high speed cutting was more pronounced than that at low speed cutting, whose abnormal wear were pull-out of grain, cracking, chipping and flanking. Thirdly, the machining quality at high speed cutting was better than that at low speed cutting. Fourthly, the tendencies of cutting forces, tool wear and surface roughness relative to cutting length were similar, but the change rates were different, especially at the initial stage. Finally, high speed cuttingare plausible to use in HDF processing, which not only improves machining quality, but also promotes production efficiency.

WOOD RESEARCH Volume 63, Number 3, 2018
Mohammad Ahmadi, Siavash Bayani, and Mearaj Sharari

Organosolv pulping of Calotropis procera by mono ethanol amine

In this study, usage of mono ethanol amine (MEA) as an organic reagent was considered in pulping of Milkweed compared with alkaline non-friendly pulping methods including Kraft and Kraft-AQ and soda-AQ. In this case, monoethanolamine was added in various ratios i.e. 100, 75, 50, 37.5 and 25% in replacement with water (MEA-water pulping). Besides, anthraquinone was added in parallel with MEA-water treatments (MEA-water -AQ ) and its effect on pulp properties has been considered. The results indicated that replacement ratio of 75/25, 240 minutes of retention time and with0.1% usage of anthraquinone showed the optimum conditions based as yield and kappa number of the pulp samples. Moreover, at the same degree of delignification, the MEA pulps showed about 15-20% higher yield based on raw material. Total unbleached MEA pulp yield is very high, ranging between 48 to 54% with kappa number of 58. For Kraft, the yield varied between 38 to 43%.

WOOD RESEARCH Volume 63, Number 3, 2018
Roman Fojtík and Kateřina Dědková

Analysis of diagnostic methods for detecting the presence of gloeophyllum spp

The development of wood use as a renewable raw material for construction caused that can be also seen as the construction of bridge structures, which have to withstand the environment. It is a modern construction using LLD or replicas of historical buildings using RD. Many of these constructions, despite impregnation, are struggling with biological pests that greatly reduce their durability. Revealing of the most dangerous ones is complex and usually cost such amount of money. Diagnostic methods and their results are different. The article deals with the comparison of the diagnosis methods of wood decaying fungi from the family of Gloeophyllaceae to the real construction.

WOOD RESEARCH Volume 63, Number 3, 2018
Bo Li and Zhankuan Zhang

Technique to improve paint utilizing efficiency of wooden board during electrostatic spraying process

A technique to improve paint utilizing efficiency of wooden board during electrostatic spraying process was proposed. An experiment was carried out for verification of its feasibility. A finite element model for electric field between spray gun and wooden board was built by ANSYS software. Experimental results show that paint weight per square meter of wooden board surface after electrostatic spraying is increased significantly when the technique is used. Simulation results show that the electric field intensity between spray gun and wooden board is increased obviously when the technique is used.