Shear strength of heat-treated solid wood bonded with polyvinyl-acetate reinforced by nanowollastonite

This study investigated the shear strength of heat-treated solid wood of three species (beech, poplar, and fir) bonded with polyvinyl-acetate (PVA) adhesive reinforced by nanowollastonite (NW). Wood specimens were heat-treated at 165°C and 185°C, and then bonded using PVA reinforced by 5% and 10% of NW. Shear strength tests parallel to the grain of bonded specimens were performed according to ASTM D143-14 (2014). The results demonstrated that the shear strength was significantly dependent upon the density of the specimens. Heat treatment decreased the shear strength of the bonded specimens considerably. This was attributed to several factors, such as a reduction in polar groups in the cell wall, increased stiffness of the cell wall after heat treatment, and a reduction in the wettability of treated wood. However, NW acted as a reinforcement agent or extender in the complex, and eventually improved the shear bond strength. Moreover, the density functional theory (DFT) proved the bond formation between calcium atoms in the NW and hydroxyl groups of cell wall polymers. The overall results indicated the potential of NW to improve the bonding strength of heat-treated wood.

Heartwood and sapwood features of Sorbus torminalis grown in iranian forests

In the present study anatomical, histometrical, chemical and physical properties of the wood of 45-year old trees were determined. For this purpose, three trees were randomly cut at Sangdeh-Mazndaran located in the northern part of Iran. Disks and logs were removed at breast height to study the respective wood properties. Fiber length, fiber diameter, fiber lumen diameter, cell wall thickness as well as lignin and cellulose content of sapwood are superior to those of heartwood. Growth rings boundaries are fairly distinct and can be distinguished by only two to three compact fiber layers. The wood is diffuse-porous and vessels are small and predominately solitary, hardly visible to the naked eye on transverse sections. Most rays are 2-seriate interspersed with only few 3-seriate and uniseriate rays, and composed of procumbent body cells with occasional marginal rows of upright and/or square cells.

Size reduction downcycling of waste wood. Review

The article includes research related to utilization of waste wood which is primarily size reduced due to its voluminity for next processing for lower value added products for about last twenty years. Procedures and results obtained by different authors were considered in one study. In this review a wood waste downcycling was consider as a process of transformation of large size wood products over their lifetime to the new products, where a size reduction is one of the first operations needed to achieve to. Incineration of each way was excluded from the present review, but second-generation biofuels are considered as potential products for the future. Two points of research selection according to origin and according to products made of waste wood was applied in this review. Comparison shown that the most industrially applicable implementation of treated particles obtained from waste wood is intended to the composite materials production as particleboards, fibreboards, cement-bonded and wood-plastics.

Study on the warm-cool and dry-wet feeling of straw board surface

To expand the application of furniture materials, the warm-cool and dry-wet tactile properties of the rice straw particleboard (RSP) surface were investigated. RSP substrates exhibiting densities equal to 757 and 554 kg.m-3 were sanded using different types of sandpaper (mesh 180#, 360#, and 600#). Psychological experiments on sensation were then conducted by bubbling for RSP substrates. By observing and comparing changes in warm-cool and dry-wet tactile properties between the RSP and other different materials, the effects of several variables on surface tactile properties, such as sandpaper types, RSP densities, and thermal conductivity of materials, were evaluated.

Mechanical and physical properties of medium density fibreboard with calcite additive

In this study, it is investigated that are calcite filler can be used in the production of medium density fiberboard. Chips have been to the process of cooking for 4-5 minutes in Asplund defibrator with the vapor pressure of 7-7.5 bar, and 180ºC temperature. 1.5% paraffin and 1% ammonium sulphate to be pulverized is added to fibers on the output of defibrillator and blowline line. Calcite fillers are prepared in a separate tank in order to use calcite instead of lignocellulosic fibers in the production of 1 m³ MDF. After that, urea formaldehyde glue is prepared as three different solutions which include the calcite, respectively with 3% (20 kg.m-3), 6% (40 kg.m-3), 9% (60 kg.m-3). The fibers are dried to moisture of 8%-12%. This press applies temperature about 185-190°C and pressure about 32-34 kg.m-2 to the mixture material for 270 seconds during pressing time. MDF panels (2100 x 4900 x 18 mm) were produced in the process. Both mechanical and physical experiments are performed on boards which are produced.

Flexural behavior of osb reinforced wood truss

In this paper, oriented strand board (OSB) on both sides of the wood truss was used to strengthen the wood truss. The flexural behavior of the reinforced wood truss was studied. The results showed that OSB was an effective technical member to improve the flexural bearing capacity of wood truss. Besides, wood truss and OSB can be firmly combined by using glue bonding and screw connections. The screws served only to apply pressure to the glued joint. And the reinforced wood trusses had good synergy and overall stability. The initial bending stiffness and ultimate bending load of the reinforced wood trusses were increased by 203.20% and 234.39% respectively. Ultimate bending load and initial bending stiffness were improved a little by making the wood truss wider. Compared with the traditional wood truss, the reinforced wood truss had the advantages of simple connection mode, less wood consumption, no rolling machine and easy fabrication.

Impact of electrical cables embedded into oriented strand board on critical heat flux

The paper deals with the research of electrical cables embedded in surface grooves of OSBs and its impact on the critical heat flux. An OSB type 3 board (structural board for use in dry or humid environments) and an electrical cable with fire reaction class B2ca have been investigated. Four different configurations of grooves were investigated. The first configuration consisted of an OSB without grooves (control sample). The second configuration consisted of an OSB with a single groove in the centre in which the electrical cable was mounted. In the third and fourth configurations, there were three and five grooves, respectively in which the electrical cables were mounted (the width of the grooves and the spacing between them was 9 mm). The critical heat flux was calculated from the ignition times at five different heat fluxes (30, 35, 40, 45 and 50 kW.m-2) by using a cone calorimeter. The obtained data showed that the OSB without grooves (first configuration) shows the lowest critical heat flux (8.6 kW.m-2) and the lowest standard deviation of ± 0.5 kW.m-2 (lower ignition resistance) compared to the other configurations (critical heat flux in the range from 9 to 10 kW.m-2 and standard deviation from 3.1 to 3.2 kW.m-2).

Influence of wet and dry cycle on properties of magnesia-bonded wood-wool panel

In this paper, magnesia-bonded wood-wool panel was subjected to different times of wet and dry cycle to analyze their effects on the physical properties and the sound absorption property of the panel from macro and micro perspective. The results showed that with the increase of the wet and dry circle times, both MOE and thickness swelling decreased and the average absorption coefficient of the specimen increased.

Genetic and selection assessment of the scots pine (Pinus sylvestris L.) in forest seed orchards

Cultivation of highly productive stands of the Scots pine is a priority task of the forestry industry. This task should be solved using the methods based on the molecular genetic analysis. Following these methods carefully will allow improving the work quality and efficiency in the forest seed farming, to control successfully the stand phytosanitary condition, as well as to use DNA markers in the in vitro culture reproduction of tree species. Our studies have shown a high level of the Scots pine genetic diversity in forest seed orchards, which is confirmed by insignificant spread of values between similar studied characteristics when analyzing the Scots pine with high morphological characteristics, selected from natural populations. Thus, genetic monitoring of the objects of permanent forest seed base of this tree species should be introduced into practice of the forest selection seed farming.

Mechanical properties and set recovery of compressed poplar with glycerin pretreatment

In order to improve the mechanical properties of low-density wood, the densified wood was fabricated. Northeast China fast-growing poplar was firstly immersed in 50% glycerin for 24 h, and then compressed under 150°C to attain 60% compression ratio with different thermal modification time (0.5, 1, and 2 h). The set recovery, modulus of elasticity (MOE), modulus of rupture (MOR) and hardness of compressed wood were tested to assess the influence of thermal modification time and wet/dry cycles on mechanical properties and set recovery of compressed poplar with glycerin pretreatment. It can be found that the thermal modification time of 1 h can be more appropriate, the first wet/dry cycle has a significant effect on mechanical properties and set recovery of compressed wood due to the dilution of glycerin during the soaking.

Blue stain in lumber industry and losses caused by cutting methods

In this study, it is aimed to determine the waste and productivity losses of Scots pine (Pinus sylvestris L.) logs that were exposed to blue stain degradation. In this context, a total of 39 timber production processes were analyzed in 7 different lumber managements using prism cutting and sharp cutting method. The main product yield and additional processing requirements were determined for flawed and flawless logs in blue stain damage. As a result of the study, it was determined that the blue stain degradation decreased the main product efficiency by 17% in the prism cutting method and by 33% in the sharp cutting method. Statistically significant differences were discovered between the efficiency values obtained as a consequence of cutting flawed and flawless logs with prism and sharp cutting methods. In addition, additional processing requirements were determined in the sharp mowing method.

Test analysis and verification of the influence of milling cutter blade shape on wood milling

In this paper, the influence law of cutting tools with different blade shapes in the process of wood milling was studied. Keeping the cutting speed, cutting depth, cutting width unchanged, the blade shapes of milling cutter were the research object, the cutting force, cutting vibration, and chip morphology change under different feed rate were discussed, the surface roughness of the processed material was analyzed under down milling and up milling. The results showed that when the feed rate increased from 6 m.min-1 to 14 m.min-1, the cutting force in up milling was less than that in downing milling, the cutting vibration of upright milling cutter with spiral curved blade was the smallest, it increased gradually in the range of 13.6 m.s-2 – 27.4 m.s-2 in up milling. On the whole, the surface roughness of the workpiece in down milling was better than that in up milling. The experimental study on the cutter milling blade shapes had a guiding significance for improving the precision of surface machining and provided a theoretical reference for the selection of process parameters in the milling process.

Timber column seismic response design

The timber column seismic response has been analyzed when it has been subjected to near-fault ground motion. The cyclic displacement and cyclic strain have been investigated. It needs to indicate in most of the literature acceleration history of earthquake used in the numerical analysis is not well clear for the reader. The results showed that the damping ratio, strain energy, and nonlinear deformation were changed in respect to the frame geometry. The innovation of this paper is to develop cycling graphs by means ABAQUS for study timber column seismic response and improve the concept of strain energy in understanding displacement mechanism.

Development of cross-laminated timber (CLT) products from stress graded canadian hem-fir

To explore the feasibility of hem-fir for CLT products, this work addressed the exploratory and pilot plant studies of hem-fir cross-laminated timber (CLT) products through mechanical tests. The hem-fir lumber was procured and then stress-graded based on dynamic modulus of elasticity (MOE). The resulted 5-ply prototype CLT products were then tested non-destructively and 3-ply pilot plant hem-fir CLT was tested destructively. The results showed that bending performance of hem-fir CLT panel can be predicted. Considering cost-competitiveness and end applications of hem-fir CLT products, the panel structure can be optimized based on the stress-graded data of hem-fir lumber.

Elastic constants of six wood species measured with the resonant beam technique

The elastic properties of six wood species were determined using the resonant beam technique. By stimulation of transverse vibrations and analyzing the responding oscillations of carefully prepared rectangular beams of wood, simultaneous determination of one Young’s modulus and two shear-moduli on one specimen is possible. Using three different cutting orientations along the principal material directions all three Young’s moduli and three shear moduli can be determined. This paper presents the application of this technique to six wood species: two softwoods, two hardwoods and two tropical woods.