WOOD RESEARCH Volume 61, Number 2, 2016
Xiurong Guo, Danfeng Du, Zhanfeng Qi, Peng Wang, and Hoseok Song

Microstructure characterization of wood fiber pit adsorbing ultrafine particles emitted by diesel engine and simulation of its influence factors

Wood fiber is a porous biomass material, which has a strong adsorption ability for the PM (particulate matter) emitted by diesel engines. Through the SEM experiments, the fact that the pits of micron wood fiber after heat-treated can adsorb lots of ultrafine particles (aerodynamic diameter is less than 1μm) is shown clearly. In simulation, the particle concentration equations and fibrous filtration theory are applied. The collection media around pits is assumed as a cylinder. The simulation results show that the pits have relatively lower collection efficiency for the particles within the diameter from 0.4 to 0.6 μm. Out of the range of 0.4 to 0.6 μm, the collection efficiency increases rapidly, which implies that the pits have higher collection efficiency to filter the particles with the diameter out of 0.4 to 0.6 μm. Among all the affecting factors on collection efficiency, the reduction of permeate flow rate and the addition of tracheid wall thickness improve the collection efficiency. However, exhaust temperature has negligible influence on the collection efficiency.

WOOD RESEARCH Volume 61, Number 2, 2016
Monika Terebesyová, Pavla Ryparová, Petr Ptáček, and Petr Kuklík

Fungicide efficacy of nanofibre textiles containing chemical preservatives for protection of wooden materials – preliminary study

The aim of presented work was to verify a possible application of nanofibre polyvinyl alcohol (PVA) textiles doped with commercially available biocides for chemical preservation of wooden materials. Fungicide efficacy of biocides based on Propiconazole, Tebuconazole, IPBC was evaluated on Norway spruce samples (Picea abies Karst. L.) 25 x 25 x 4 mm covered by the nanofibre textiles, against the wood destroying fungus Coniophora puteana during 28 days. Decay resistance of spruce samples with the fungicidally treated layer was valued on the base of weight loss (Δm) criteria. The durability of spruce samples significantly increased after incorporation of fungicides into the nanofibre textiles (Δm from 0.2 to 3.7 %), but the influence of the stabilization process was also reflected.

WOOD RESEARCH Volume 61, Number 2, 2016
Tibertius Agus Prayitno and Ragil Widyorini

The adhesion properties of wood preserved with natural preservatives

Wood preservation technology has been using synthetic preservatives for a long time. However, some disadvantages have been recorded such as quality degradation of environment, killing more non target wood destroying organism. Since environment quality requirement has been up lifted, then general wood processing and wood preservation paradigm has to change from utilization of synthetic to natural wood preservatives. The new natural wood preservatives have their own properties and influence differently on wood adhesion. Wood adhesive based products such as plywood, lamination, particleboard and fiberboard use wood waste consisting of all kind of processes wood such as naturally preserved wood. The objective of this research is to know the effect of naturally wood preservatives on wood adhesion properties. This research was conducted by wood adhesion block method. The fast growing teak plantation wood was chosen since this type of teak wood was claimed as low grade of wood quality. This type of wood has high portion of sapwood which is susceptible to wood destroying organism. The source of natural, local wood preservatives are gadung tubers, pulai bark and kumis kucing leaves. The wood adhesive used was bio-industrial PVAc in the form of glue paste. Extraction procedure of natural wood preservatives followed ASTM D1110-1984. The procured naturally extracts was processed to obtain extract concentration 1.00 gram per liter concentration. Wood preservative application used padding method on the wood surface by 0; 1; 2 and 3 application times. Each padding layer processed was applied after the former one was air dried. Wood adhesion test followed block type with 40#/MSGL glue spread and cold press system. Compression shear test of block samples followed British Standard (1957). This adhesion test method was chosen since the method has proven as efficient and effective adhesion test in the laboratory. The research results showed that interaction factor of natural wood preservative and padding application did not affect to the adhesion strength. This adhesion strength was affected by single factor of natural wood preservative and padding application. The highest adhesion strength of 94.29 kg.cm-2 was resulted by pulai bark followed by gadung tubers (80.61 kg.cm-2) and kumis kucing leaves (55.31 kg.cm-2). Padding application exerted a negative correlation to adhesion strength. Higher padding application number of natural preservative on the wood surface, lower adhesion strength. The reduction of adhesion strength of 1; 2 and 3 padding application resulted 20; 42 and 66 % for gadung tubers. Pulai bark extract reduced 24; 30 and 57 % while kumis kucing leaves lowered 22; 37 and 75 % consecutively.

WOOD RESEARCH Volume 61, Number 2, 2016
Alireza Bastani, Holger Militz, Stergios Adamopoulos, and Anti Rohumaa

Development of bonding strength of modified birch veneers during adhesive curing

This study investigated the bonding strength development of furfurylated, N-methylol melamine (NMM) modified and thermally treated birch veneers glued with hot curing phenol formaldehyde (PF) adhesive in different pressing (20, 160 s) and open assembly times (20 s, 10 min). For testing, the automated bonding evaluation system ABES was used with 2 N.mm-2 applied pressure at 130°C. The bonding strength of both modified and unmodified samples increased significantly by prolongation of the pressing time from 20 to 160 s in all cases and for both open assembly times. A deviation was observed for the samples treated at 220°C and at 20 s open assembly time. With the exception of NMM modified veneers, bonding strength did not change significantly by increasing the assembly time in the case of 20 s pressing for both modified and unmodified samples. At 160 s pressing time, extension of the assembly time developed a better bonding for controls, NMM modified and thermally treated veneers at 180°C. The combination of 10 min assembly time and 160 s pressing time proved as the optimal bonding condition for controls, NMM modified and thermally treated veneers at 180°C while the highest bonding strength was noted in 20 assembly time and 160 s pressing time for furfurylated veneers. In most of the cases modification affected negatively the bonding performance of the veneers, in particular for furfurylated and NMM modified samples.

WOOD RESEARCH Volume 61, Number 2, 2016
Juraj Gigac, Monika Stankovská, Elena Opálená, and Pažitný Andrej

The effect of pigments and binders on inkjet print quality

The effect of silica and calcium carbonate pigments, polyvinyl alcohol and cationic starch binders combined with high-cationic polymers on physical-chemical and printing properties of coated papers were studied. The best printing properties were obtained with coating colour based on silica. Colour gamut significantly improved when the inkjet ink contact angle decreased below 15°. The water fastness was influenced with specific charge density of coating colour. Application of silica provided papers with the largest inkjet ink wetting, colour gamut area, print sharpness and surface roughness. By using of polyvinyl alcohol a high colour gamut area was reached but it resulted in a low print sharpness in comparison with cationic starch. High-cationic polymer poly-DADMAC showed a more significant effect on all printing properties of coated paper in comparison with SMAI 1000. The final inkjet print quality depends on structural and chemical properties of coating.

WOOD RESEARCH Volume 61, Number 2, 2016
Hong Yun, Kaifu Li, Dengyun Tu, and Chuanshuang Hu

Effect of heat treatment on bamboo fiber morphology crystallinity and mechanical properties

This study aimed to investigate the fiber morphology, crystalline structure and mechanical properties of heat-treated bamboo. Moso bamboo was treated by superheated steam at 120, 140, 160, and 180ºC. Fiber morphology and crystalline structure of heat-treated Moso bamboo were researched by transmission electron microscope and X-ray diffraction. The mechanical properties of heat-treated bamboo were tested in the paper. The result showed that the relative crystallinity and length-width ratio of heat-treated bamboo were increased with increased temperature. The elastic modulus of bamboo was increased as the temperature rose from 120 to 140ºC. and then decreased with higher temperature, which was associated with the increase of the crystallinity.

WOOD RESEARCH Volume 61, Number 2, 2016
Jaroslav Sandanus, Kristián Sógel, and Miloš Slivanský

Results of rheological test on timber trusses

In the paper the results of exceptional experimentation are presented, which focuses on the long-term loading of metal plate connected wood trusses. The uniqueness of research project is given by real dimensions of long-span samples and by the term of loading over one year. The aims of long-term experimentation were detection of two main parameters. The magnitude of additional deflections and time of load action needed for their development. In the paper the deflection curves are presented, namely time dependence of deflections. In the paper the recommendations for producers of metal plate connected wood trusses and for structural engineers are mentioned. The purpose of that research project is to increase the safety and reliability of timber load-bearing structures.

WOOD RESEARCH Volume 61, Number 2, 2016
Qing Ke, Lin Lin, Shaoyu Chen, Fan Zhang, and Yachi Zhang

Optimization of L-shaped corner dowel joint in pine using finite element analysis with Taguchi method

The strength of the furniture corner-joints in pine remains unknown, and the lack of information restricts its use in furniture industry. Therefore, the aim of this study is to optimize the strength of L-shaped corner dowel joint in pine under compression loads using finite element analysis (FEA) with Taguchi method. By adopting a L9-34 Taguchi orthodoxy array (OA), four experiment factors (i.e., structure style, tenon length, tenon diameter, and tenon gap), each at three levels, were carried out to determine the optimal combination of factors and levels for the von mises stress using ANSYS software. The results of Signal-to-Noise ratio (S/N) analysis and the analysis of variance (ANOVA) revealed that the optimal L-shaped corner dowel joint in pine is 45° Bevel Butt in structure style, 24 in tenon length, 6 in tenon diameter and 20 mm in tenon gap.

WOOD RESEARCH Volume 61, Number 2, 2016
Paola Cetera, Luigi Todaro, Teresa Lovaglio, Nicola Moretti, and Angelo Rita

Steaming treatment decreases MOE and compression strength of Turkey oak wood

This study examined the mechanical properties of Turkey oak (Quercus cerris L.) wood before and after combined steam and thermal treatments under vacuum conditions. Wood was steamed at 100 to 110°C and thermally treated under vacuum at 160°C by the press-vacuum or thermo-vacuum process. Treated material was characterized in terms of the modulus of elasticity (MOE) and compression strength of heartwood and sapwood. The MOE was established using a nondestructive technique based on the measurement of ultrasonic pulse propagation. Results differed depending on the treatment or combination of treatments, and showed that the steaming process strongly affected the MOE. Thermo-vacuum treatment increased the compression strength, whereas steaming had the opposite effect.

WOOD RESEARCH Volume 61, Number 2, 2016
Mehmet Yeniocak, Osman Goktas, Ertan Ozen, and Ahmet Gecgel

Improving mechanical and physical properties of particleboard made from vine (Vitis vinifera L.) prunings by addition reinforcement materials

The main goal of this study was to improve mechanical and physical properties of particleboards made from vine (Vitis vinifera L.) prunings by addition of reinforcement materials. In Turkey, there are 462.000 hectare areas for vine cultivation. Annually, approximately 2.345.000 ton vine pruning parts residues are remained. Every season, large quantities of vine prunings are left as by-products in the fields, and unfortunately they are not utilized properly by the related industries. In this study, vine prunings and particles were used as raw material for three-layer flat pressed particleboards. Cord fabric fibre (CFF) (mixed), Cord fabric (CF) (sandwiched), plaster mesh (PM) (sandwiched), polyester fibre (PF) (sandwiched) were used as reinforcement materials. A commercial urea-formaldehyde (UF) resin was used as binder. Small size experimental panels (56x56x2 cm) were manufactured. Some physical properties (like, thickness swelling (TS), density, moisture content (MC) and mechanical properties (like, modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB) perpendicular screw-holding (PSH, ⊥), lateral screw-holding strengths (SHS, //), and tensile strength parallel to surface properties of panels were determined. The results indicated that some properties of the reinforced panels can give satisfactory values compared to control (non reinforcement) panels. Generally the reinforcement materials increased the mechanical properties of the particleboards. Such particleboards can meet the standards for isolation panels and interior-use.

WOOD RESEARCH Volume 61, Number 2, 2016
Rongrong Li, Xiaolei Guo, Pingxiang Cao, and Xiaodong (Alice) Wang

Optimization of laser cutting parameters for recombinant bamboo based on response surface methodology

A means for selecting the optimal process parameters for the laser cutting of recombinant bamboo, based on the design of experiments (DOE) approach, was presented. Recombinant bamboo with thicknesses of 5, 10, and 15 mm was cut by a CO2 laser. The parameters investigated were the laser power, air pressure, and cutting speed. The results were compared using a number of process responses which define the efficiency of the cutting, including the upper kerf (UK) width, lower kerf (LK) width, and the ratio of upper-to-lower kerfs. Mathematical models were developed to establish the relationship between the process parameters and response parameters; special graphs were drawn for this purpose. Finally, a numerical optimization was performed to find out the optimal process settings to achieve a minimumupper-to-lower kerf ratio.

WOOD RESEARCH Volume 61, Number 2, 2016
Piotr Mańkowski, Paweł Kozakiewicz, and Michał Drożdżek

The selected properties of fossil oak wood from medieval burgh in Płońsk

Oak wood is characterized by a high resistance to effects of biotic factors and thereby it is often found in archaeological excavations. While lying over many years in the wet environment, the wood turns black as a result of reaction with iron compounds. Archaeological oak is a valuable raw material. In this paper selected mechanical and chemical properties of a thousand years archaeological oak were investigated. Then the archaeological oak properties were examined and compared with the contemporary oak wood. Archaeological oak wood as well as contemporary oak wood has a directly proportional relationship between MOE (modulus of elasticity) and wood density, and similar relationships between wood density and compressive strength, bending strength, content of mineral substances. Contemporary wood of the same density as the archaeological oak wood would show significantly higher mechanical properties.

WOOD RESEARCH Volume 61, Number 2, 2016
Cengiz Gűler, Halil ibrahim Sahin, and Sevcan Yeniay

The potential for using corn stalks as a raw material for production particleboard with industrial wood chips

In this study particleboards were manufactured from mixtures of corn stalks (Zea mays indurate Sturt.) and industrial woodchips at several ratios. The corn stalks and industrial wood particles were mixed at ratios 0, 25, 50, 75 and 100 % respectively. The suitability of corn stalks chips for particleboard production was examined. Urea formaldehyde resin was used as a binder in 3-layers particleboards. Produced panels were tested for certain mechanical and physical properties. The manufactured boards were tested according to EN standards. In addition, the chemical properties of corn stalks were evaluated. Experimental results indicated that increase in corn stalk chips in the mixture generally diminished the mechanical and physical properties.

WOOD RESEARCH Volume 61, Number 2, 2016
Lucie Jezerska, Ondrej Zajonc, Jan Vyletelek, and Jiri Zegzulka

Mechanical material properties effect on pelletization

The relation between the mechanical properties of input materials and the smoothness of material flow from a storage bin, cohesion variability of the compressed powder mixtures, and pelletization process were studied. Three material types were examined: Pyrolysis char from biomass – spruce wood (Picea abies L.), compost and spruce sawdust. Increased input material compressibility and cohesion affected the resulting durability and hardness of the pellets. Additional important material parameters affecting the pelletization process and final pellet quality include flowability and wall friction angle: Pellet durability and hardness increases with decreasing flowability (shift to the cohesive materials mode) and wall angle of the incoming materials. Those parameters are taken into account when designing conveyors. Application of the Quality by Design (QbD) approach to the prediction of behaviour in the pelletization process is outlined. The feasibility of inferring acceptable pelletization process behaviour from the mechanical-physical properties of the input materials is demonstrated.

WOOD RESEARCH Volume 61, Number 2, 2016
Oliver-Villanueva José-Vicente, García-Andújar Enrique, and Gascón-Garrido Patricia

Analysis of durability and dimensional stability of hydrothermal carbonized wooden pellets

Hydrothermal carbonization (HTC) is a chemical pretreatment of wood waste for convert it in biochar by the application of high temperatures and pressures in a reaction time that do not exceed 10 hours. One of the main applications of the HTC biochar is as pellets. In this research durability against fungal decay and dimensional stability associated with relative humidity changes of HTC pellets were analyzed and evaluated. A comparison of these properties between HTC pellets and wooden EN+ pellets has been carried out. HTC pellets are significantly more durable against fungal attack, more dimensionally stable against relative humidity changes and denser than wood pellets, which confers better properties for logistics processes like storage and transport.

WOOD RESEARCH Volume 61, Number 2, 2016
Cosmin Spirchez, Aurel Lunguleasa, and Tatiana Griu (Dobrev)

Testing model for assessment of lignocellulose-based pellets

This paper aims to find a simple testing and assessment model applicable to lignocellulose-based pellets, for the purpose of making the appropriate selection from the market. It is analysed the main tests of pellets, as density, caloric value and shear strength, for three different types of pellets bought from the competitive market. Afterwards is detailed the method of operation for the shear strength due to its not so frequent use. Finally, based on the tested values and limits required by the existing standards, it is determined a simple method for assessing for pellets, pointing out the closeness of each tested value to the standard limits.