Articles

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The effect of combined melamine-resin-colouring agent modification on water related properties of beech wood

Beech wood (Fagus sylvatica L.) was modified with aqueous solutions of methylated N-methylol melamine (NMM) and a metal-complex dye and the water related properties were determined. Wood blocks, treated to the highest weight percent gain (WPG), attained approximately 5 % cell wall bulking and 30 % anti-swelling efficiency (ASE) after ten cycles of water saturation and drying. The metal-complex dye was stably fixed in the resin matrix and was hardly washed out. The equilibrium moisture content of the modified samples related to the dry mass of untreated beech wood (EMCR) was not considerably reduced compared to the EMC of the control. The maximum swelling of the modified samples as a result of vapour sorption was only reduced above 65 % relative humidity compared to the control. Capillary water uptake of wood was significantly reduced by the resin modification. The results indicate the potential of the combined modification to improve the water related properties of wood.

The use of complex impedance as a parameter for wood differentiation

Electrical and dielectric wood properties are used in many applications. Wood parameters such as resistance, conductivity, complex impedance can be used e.g. for determination fungal decay, moisture content and density or for defects detection. In this work, the complex impedance of seven wood species was measured for frequency range 10 Hz – 1 MHz. The specimens were cut from sapwood and heartwood and measurements were conducted with parallel and perpendicular orientation of the electrical field with respect to the visible grain. The impedance of various wood types differs significantly for frequencies below 2 kHz. Therefore, for wood samples classification, the complex impedance values measured in frequency 1.1 kHz were used. Three different classification methods were used for clustering. Results show that the impedance can be a useful parameter for wood differentiation and membership of each group depends on number of clusters.

Determination of acoustic parameters of bio-based materials distended for building: Application case to Aleppo pine wood cork and their composites

In this work, we are interested to incorporating acoustic comfort in buildings by using bio-based materials. More specifically, this work aims to determinate experimentally the sound absorption coefficient (α) and the sound reduction index (R) in three different samples. The first sample consists of Aleppo pine wood (Pinus halepensis) with two different configurations (solid wood and laminated timber wood). The second sample consists of a black agglomerated cork (suber) with two different thicknesses. The third sample consists of sandwich assemblies obtained by superimposing two wooden layers (solid or laminated timber wood) bonded with an inter layer cork. In this experimentation, we have used Kundt tube to determine sound absorption coefficient and AcouSYS V2.0 software to predict the sound reduction index. The obtained results showed that the first parameter (α) is influenced by the thickness of material. The second parameter (R) of symmetrical and asymmetrical sandwich assemblies of solid laminated timber wood with an interlayer of black agglomerated cork even shows good performances.

The influence of density of test specimens on the quality assessment of retarding effects of fire retardants

Test methods evaluating wood flame retardant efficiency are comprised of a parameter which is often considered to be an evaluation criterion and its calculation includes the weight of the test specimen or takes into account the change of its weight during the test. In this case, the overall result may be affected not only by the weight of the test specimens, but also by their density. Our aim is to observe the influence of density while evaluating the efficiency of wood flame retardants.

Surface characteristics of Oriental beech and Scots pine woods heat-treated above 200°C

Heat-treated of Oriental beech (Fagus orientalis L.) and Scots pine (Pinus sylvestris L.) woods were carried out by hot air in an oven for 1, 3, and 5 hours at 205, 220, and 235°C. After heat treatments, some surface properties such as color and gloss changes of both wood specimens were evaluated. Our results showed that heat treatment caused decrease in gloss values of Oriental beech and Scots pine wood specimens. Higher treatment temperature and duration resulted in higher gloss loss of wood specimens after heat treatments. Heat-treated wood became darker tonality, especially; it became more darkening after 3 and 5 hours heat treatments. Generally according to our results, Δa* and Δb* decreased after heat treatments. Oriental beech wood tended to become less reddish than Scots pine after heat treatments. Δa*, Δb* and ΔE* of heat-treated Oriental beech and Scots pine decreased with increasing treatment temperature and duration.

Radial variation of fiber dimensions, annual ring width, and wood density from natural and plantation trees of Alder (Alnus glutinosa) wood

The aim of this research was to determine radial variations of some wood properties from natural and plantation trees of Alnus glutinosa. Oven-dried wood density (WD), fiber cell features, and annual ring width (ARW) were determined in radial positions of stem at breast height of tree. The results showed that the cultivation methods had significant influence on the fiber length (FL), fiber diameter (FD) and ARW. The effect of interaction between radial position and cultivation methods on anatomical features was not significant, except for cell wall thickeness (CWT). Fiber cell features and WD increased with distance from pith for both cultivations trees. The ARW decreased with increasing the cambial age in both cultivation methods. The average of FL and ARW in plantation trees was higher than those in natural trees. Widest FD was found in natural forest. There were significant relationships between ARW-WD and WD-FD for natural forest and between ARW-WD, ARW-CWT and WD-FL for plantation forest. About 67 % of WD variation in natural and plantation trees were related to FD and ARW, respectively. Due to high FL and ARW, wood from planted trees could be suitable for paper production than wood from natural trees.