WOOD RESEARCH Volume 66, Number 5, 2021
Tomasz Ozyhar

Short notes: Application of mineral filler in medium density fiberboard (Mdf) and its effect On material properties as a function of particle size

The addition of inorganic filler material in medium density fiberboard (MDF) and the effect on material properties as a function of particle size was examined. Medium density fiberboard was manufactured in a laboratory scale environment to a target raw density of 750 kgm-3. Wood fibers were replaced by using calcium carbonate at 3 and 10 wt.% using fillers with weighted median particle sizes of d50 = 2.0 μm and d50 = 30 μm, respectively. Urea formaldehyde resin was used as binder in all MDF. The influence of filler addition on the modulus of elasticity, bending and tensile strength, dimensional stability and liquid permeability was investigated. The results demonstrate the effect of filler content and its dependence on particle size. The addition of filler with d50 = 30 μm does not have any influence on material properties up to a filler content of 10 wt.%. Using the finer filler with d50 = 2.0 μm at 10 wt.% filler, the quantity significantly increases the water adsorption and swelling behavior and reduces the strength properties of the MDF.

WOOD RESEARCH Volume 61, Number 6, 2016
Alperen Kaymakci, Nadir Ayrilmis, and Huseyin Akkilic

Utilization of tinder fungus as filler in production of HDPe/wood composite

Selected physical and mechanical properties of high density polyethylene (HDPE) composites filled with various mixtures of wood flour and tinder fungus (Fomes fomentarius) were investigated. For this aim, different mixtures of tinder fungus flour and wood flour (0/40, 10/30, 20/20, and 30/10, and 40/0) (by weight) were compounded with HDPE with a coupling agent (maleic anhydride grafted polyethylene (MAPE) in a twin screw co-rotating extruder. The test specimens were produced by injection moulding machine. The thickness swelling and water absorption of the HDPE/wood composites significantly decreased with increasing content of the tinder fungus flour. The mechanical properties of the composites were negatively affected by increasing amount of tinder fungus flour but there were no significant differences up to 30 wt % tinder fungus content, except for the tensile strength. The optimum physical and mechanical properties for the filled HDPE composites were found to be a 10/30/60/3 formulation of wood flour, tinder fungus, HDPE, and MAPE, respectively.

WOOD RESEARCH Volume 61, Number 6, 2016
ROMAN RÉH and Martin Guoth

Thermoplastic plywood and it’s drawback when moderately heated

GradaTM is new plywood which contains the thermoplastic adhesive. There are so far two material versions 1000 and 2000 which have wide potential in production of wooden products with new perspective of manufacturing. This paper investigates possibilities of including GradaTM material and its versions in skateboard production. Bending strengths at the moderate heat up of this material are presented, specifically at 30, 40°C for both material versions. All increased temperatures are compared to the room temperature (20°C). Mechanical properties that were obtained from the test are modulus of elasticity, modulus of rapture, and stroke strain. The results show the undesirable level of changes present in both versions however version 1000 acts significantly better than 2000.

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
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
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 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
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
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 62, Number 2, 2017
Wei Sun, Xiaokai Mu, Qingchao Sun, and Weiqiang Huang

The impacts analysis of moisture content on mechanical properties of wormwood stem

The disposable chopsticks caused a large amount resources waste of bamboo and wood. Thus, it has a significant resources and environmental benefits using wormwood stem as raw materials to make disposable chopsticks. In this paper, the radial compression and bending performances of wormwood stem were tested with different moisture content, which provide a reference for reasonably design the grinding device of wormwood stem and the feasibility of wormwood stem instead of bamboo chopsticks. The test results show that: the mechanical properties decrease with the increase of moisture content. In the actual grinding process, the moisture content of wormwood stem is controlled about 20%, it can withstand the radial force of 600N and the bending force of 41N, which meet the load requirements of the grinding processing and use. This study provides a theoretical basis for reasonably design grinding device of wormwood stem, producing and storing high quality herbal chopsticks.

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 63, Number 2, 2018
Enhua Xi

Dynamic relationship between mechanical properties and chemical composition distribution of wood cell walls

Wood is a natural composite material with a complex structure. Its mechanical properties are mainly due to the cell walls. In order to investigate the relationship between mechanical properties and chemical composition of wood cell wall. Nanoindentation and Raman imaging were used to characterize the longitudinal mechanical properties and chemical composition distribution of wood fibers of three years old fast-growing poplar (Populus×euramericana cv. ‘74 /76’) during the growing season at different times. The results were showed that the content and distribution of cellulose and lignin are closely related to the mechanical properties of wood fiber cell walls, especially the cellulose for the longitudinal elastic modulus and the lignin for the hardness of cell walls. It was also demonstrated that the longitudinal elastic modulus and hardness of the secondary wall 2 layer (S2) were strongly correlated to the micro fibril angle (MFA) and crystallinity of cellulose during the active phase.

WOOD RESEARCH Volume 66, Number 4, 2021
Hess Dominik, Pařil Petr, Dömény Jakub, and Baar Jan

Permeability and mechanical behaviour of microwave pre-treated Norway spruce ripewood

This is a study of the influence of microwave (MW) pre-treatment on the permeability of Norway spruce ripewood (Picea abies L. Karst) as it affects its mechanical properties. Specimens were treated under variable moisture content, MW intensity, and impregnation processes. According to the results, the specimens with an initial moisture content of 45–65% exhibited the highest permeability values compared to reference samples. An insignificant difference was found between MW pre-treatments at 2 and 3 kW. Statistically significant results were found after long-time (24h) vacuum-pressure impregnation (LP). The average retention value following LP was 132 kg.m-3, which is almost three times greater than the MW-treated groups impregnated in a short-time vacuum-pressure process. The average depth of penetration after LP was 2.0 mm and the proportion of the impregnation area following LP was 17.6%. MW pre-treatment had no effect on the impregnability or the mechanical properties of the wood; other MW regimes are open for further examination.

WOOD RESEARCH Volume 64, Number 6, 2019
Zoltán Pásztory, ZOLTÁN BÖRCSÖK, Peter Adamik, and Dimitrios Tsalagkas

Internal fiberglass mesh reinforced bark-based panels

One-layer bark panels were internally reinforced with two different grid sizes fiberglass mesh sheets (M1 and M2). The thermal conductivity, water absorption, thickness swelling, static bending properties and internal bond strength of these panels were tested. The reinforcement doesn’t affect the thermal conductivity, but the physical and mechanical properties of the panel were improved. The thickness swelling was reduced by 7.43% and 12.93%; the water uptake decreased by 4.93% and 16.32% for the M1 and M2 sheets, respectively. MOR increased from 0.54 MPa to 2.44 and 2.1 MPa, and MOE increased from 0.28 GPa to 0.66 and 0.63 GPa, respectively. The internal bond didn’t change. The findings indicate that it is possible to produce internal reinforced bark panels for insulation materials depending on the characteristics and tensile properties of the reinforcing materials, as well as the adhesion properties and interfacial interaction of the composite materials.

WOOD RESEARCH Volume 64, Number 5, 2019
Wenbo Che, Zefang Xiao, and Yanjun Xie

Modification of radiata pine wood with low molecular weight modifying agents and large molecular weight styrene/acrylic acid copolymer dispersion

Our previous study revealed that treatment with aqueous styrene/acrylic acid copolymer (SA) is a cell-lumen filling process, and the treated wood exhibited negative values for cell wall bulking efficiency (BE) and anti-swelling efficiency (ASE). In this study, three low-molecular-weight agents (LMWAs), 1, 3-dimethylol-4, 5-dihydroxyethyleneurea (DM, 10%), glutaraldehyde (GA, 10%), and n-methylol acrylamide (NMA, 10%), were separately combined with SA (5, 10, 15, or 20%) and used to modify radiata pine wood at the levels of cell walls and cell lumens. The combinative treatments caused positive BE and ASE values, indicating restrained wood deformation, likely due to the diffusion and reaction of LMWAs in the wood cell walls. Infrared spectroscopy and dynamic mechanical analysis showed that LMWAs exhibit little reaction with SA, and the SA copolymer retains thermoplasticity in the wood cell lumen. The combinative treatments resulted in considerable improvement in bending modulus, bending strength, and compression strength of wood of 36, 36, and 124%, respectively, but there was little effect on impact strength. These findings confirm that LMWAs can act as cell wall modifying agents to synergistically improve wood properties, especially the dimensionally stability, when used together with SA.

WOOD RESEARCH Volume 64, Number 4, 2019
SHAOXIANG CAI, Shouheng Hu, YANJUN LI, Xinzhou Wang, Lican Chen, and Jun Li

Nanomechanical behavior of wood cell walls observed by different indentation loading prerequisites

The variations of nanomechanical behavior of wood cell walls under different peak loads, loading times, and holding times were studied. Samples were separately loaded to preset peak loads of 100, 150, 200, 250 and 300 μN. Changes in the micromechanical properties were tracked in the longitudinal direction to determine change values of the elastic modulus and hardness. Moreover, the creep behavior was also analyzed under different holding times. It was found that the longer the holding time, the larger the creep ratio of all of the samples, and the creep rate decreased slowly with longer loading times. Finally, when the peak load was larger, the displacement rate and strain rate increased, but the strain rate in each test exhibited a tendency to become constant after 10 s.

WOOD RESEARCH Volume 64, Number 4, 2019
Ondřej Schönfelder, Aleš Zeidler, Vlastimil Borůvka, and Lukáš Bílek

Impact of silvicultural measures on the quality of Scots pine wood. Part I. effect of regeneration method

This study deals with the influence of the silvicultural measures on selected mechanical properties of Scots pine (Pinus sylvestris L.) wood in the Czech Republic. Sample trees were selected at two different localities that are characteristic of Scots pine growth, and they represent two different Scots pine regeneration methods, namely the clear-cutting and shelterwood regeneration method. We tested compressive strength and impact bending strength. The density of the wood was also evaluated as a factor influencing strength characteristics. The shelterwood regeneration method shows higher values in most of the investigated characteristics (49.3 MPa for the shelterwood method and 44.6 MPa for the clear-cutting method in the case of compressive strength); however, these differences are not significant for the processing industry. Another positive effect of the shelterwood regeneration method is the even distribution of the properties within the trunk in radial direction in contrast to clear-cutting method.

WOOD RESEARCH Volume 64, Number 4, 2019
Radosław Mirski, Dorota Dziurka, and Aleksandra Banaszak

Effects of manufacture conditions on physical and mechanical properties of rape-polymer boards

The paper presents a method of manufacturing boards composed of lignin-cellulose chips and thermoplastic polymers (waste-based particle polymer composites, WPPC) by means of flat pressing. Rape chips, similar in size to wood chips in traditional particleboards, served as filling material, and polyethylene and polypropylene made up the outer layers. The polymers enriched only the external layers, as this allowed for considerable shortening of pressing time. The resulting boards featured satisfactory properties as compared with control, not polymer covered boards. Our study identified a temperature of 220°C and low moisture content of the polymer-containing layers as favorable for production of this type of boards. We also found out that using a sublayer with higher moisture content not only shortened the pressing time, but also improved the board properties evaluated by a bend test.