The anatomical structures of both untreated and thermo-vacuum treated (the temperature of 200°C, the duration of 4h and the relative pressure of -0.08 MPa) Szemao pine wood (Pinus kesiya var. langbianensis) and alder birch wood (Betula alnoides) were observated and analysed by light microscopy. The obtained results were as follows. (1) Szemao pine wood with thiner earlywood cell walls and thicker latewood cell walls, which was an abrupt transition from earlywood to latewood, was not susceptible to the thermo-vacuum treatment (TVT) in this test. Only smaller radial cracks were observed in the cross section, and ray parenchyma cells which they were non-lignified cells were partially destroyed. Longitudinal tracheids walls remained intact and were not destroyed. (2) No destruction was also observed except part of the scalarform perforations plates in alder birch wood under the TVT. The results indicated that effects of the TVT on the anatomical structures of woods were slight. In addition, the extractives of both szemao pine wood and alder birch wood were removed, playing an important roles in improving the permeability of wood after the TVT.
Gaharu or agarwood is produced by certain trees in response to fungal infections and wounds. The response is a pathological process that alters the physiological and chemical compounds produced in tree wood, yielding a fragrant resinous material. We investigated the density and hardness properties of agarwood using the drilling resistance method in 25 disks of Aquilaria malaccensis that had previously been inoculated with Fusarium solani. A micro drilling technique was applied in two directions across the diameter of the disks to measure resistance, starting in the part containing agarwood. In addition, hardness properties were determined based on the Janka test and density was measured based on the gravimetric method. We found that hardness properties varied greatly in disks containing agarwood. A low correlation was found between the amplitude of resistance and hardness and density, indicating that other variables beyond density are also involved in the changes of wood properties in agarwood. A strong correlation was observed between hardness and wood density.
The structure of both cambium and the last-differentiated cells from cambium influence the adhesion of bark on wood. In the submitted paper, the bark/wood adhesion is evaluated by means of measuring the shear strength in longitudinal and tangential direction of the wood/bark interface on woody plant beech (Fagus sylvatica L.) during one year. The growing period and dormant period and moisture of the wood/bark interface proved to be important factors influencing the shear strength. The shear strength measured during the dormant period in the greenstate showed values approximately 100% higher than those measured during the growing period. Considering the 12%-moisture, the values of shear strength proved to be circa 300% higher in comparison to the green state. The shear area during the dormant period was led through the zone of the last-created sieve tubes of non-collapsed late phloem, whereas during the growing period the shear area passed through the cambium zone. The structure of shear areas is also significantly influenced by diverse structure of narrow and wide phloem rays.
Dynamic thermo-gravimetric analysis under nitrogen was applied to investigate the thermal decomposition process of wood/HDPE composites (WPC) modified with different amount of ground tire rubber (GTR). Degradation models, including the Friedman and Flynn-Wall-Ozawa (F-W-O) were used to determine the apparent activation energy (Ea) of various materials. Composites with various GTR contents exhibited a similar two-stage degradation process. Initial decomposition temperature (T0) of the composites gradually decreased from 250.1°C to 238.2°C with the increasing GTR concentration, while the peak temperature (Tp) values remained about the same. Kinetic analysis demonstrated an average activation energy decreasing with the incorporation of 5 % GTR within the composites through both methods, but no big difference was observed with further increasing the GTR content from 5 % to 15 %. The established thermal decomposition kinetic parameters allow developing the reutilization of waste tire rubber in composite materials with appropriate loading level.
The article describes the method of evaluation and preparation of fluting liners produced from semichemical pulp of waste wood particle boards (PB) and oriented strand boards (OSB) and after the combination with old corrugated cardboards (OCC) to improve strength properties. The semichemical pulp was obtained by a mildly alkaline boiling process from two fractions of waste PB and OSB. Properties as thickness, bulk density, gurley, tensile strength, tensile index, breaking length, burst index, CMT30 and SCT were monitored on lab sheets 127 g.m-2 and 170 g.m-2. Values of pH and residual NaOH and Na2CO3 were determined in batch leachate.
The dielectric properties of seven wood species from Poland were measured as a function of frequency and grain orientation of wood. Measurements were conducted parallel and perpendicular with respect to the visible grain for specimen cut from sapwood and heartwood, at frequencies ranging from 1 kHz to 1 MHz. Both, relative permittivity and loss coefficient were affected by frequency and anisotropic direction. The most significant influence of wood species on dielectric wood properties was observed below 5 kHz for relative permittivity and below 200 kHz for loss coefficient. The relative permittivity decreases with increasing frequency and loss coefficient increases with increasing frequency (at frequencies above 200 kHz) for all wood species and fiber orientation. Understanding the dependencies between dielectric parameters of wood and other wood parameters at frequency range from 1 kHz to 1 MHz is important when wood is used for electrical insulation or in high-frequency drying.
This study was aimed to investigate the gloss, surface hardness, surface roughness, and color changes of Scots pine that was treated with some chemicals after six months of weathering exposure. Chromated copper boron (CCB), vacsol aqua, and imersol aqua were used as the impregnation chemicals. Scots pine wood specimens were impregnated with 3% aqueous solutions of the chemicals according to ASTM standards.The results showed that while chemical treatment caused a decrease in surface hardness, gloss, and lightness of wood specimens, it increased the surface roughness of the wood before weathering. While the gloss values of all treated Scots pine specimens increased after weathering, the gloss loss was observed for the untreated specimen after weathering. All of the treated and untreated Scots pine wood surfaces were softened after weathering. The chemical treatment caused a decrease of surface roughness of wood after weathering. While in terms of the gloss, surface hardness, and surface roughness changes, the vacsol aqua-treated pine specimens gave the best results. The CCB-treated Scots pine showed the best color stability after weathering.
This paper deals with changes in roughness and crack formation after surface embossing of aspen wood. Embossing was based on pushing a wedge with 45° angle into three embossing depths, i.e. 2, 4 and 6 mm. The surface roughness before and after embossing was evaluated on the basis of the arithmetical mean deviation of the roughness profile, Ra. Surface quality measurements were carried out in perpendicular (transversal), parallel (parallel) and perpendicular/parallel to the wood grain. (Embossment area quality was evaluated by the mean of portion of cracks in embossment). This evaluation was based on a digital image of the embossed area and a subsequent calculation of the portion of the cracked area in relation to the total evaluated area. Increasing the embossing depth has a positive impact on the quality of the embossed surface, i.e. the highest quality was generally achieved with an embossing depth of 6 mm. The worst surface quality was achieved with the perpendicular orientation of the wedge regardless of the direction of the roughness measurement.
Our work on the physical properties of wood in hardwood species, Quercus robur L., Q. petraea (Matts) Liebl., and Q. pyrenaica Willd., for study its use in cooperage, began with the proportion appraisal of bark, sapwood, and heartwood, and its relationship with age, to know and assess the variation thereof in the Galician oaks. To properly perform our study, it was necessary to fell several Quercus trees within the study area (Galicia, NW Spain). In total, 45 trees were selected in 15 different stands located in the Galician provinces of Lugo and Ourense, from which we obtained 45 slices of wood at 60 cm height on the tree trunk. There are many anatomical differences between hardwood and softwood species; however wood parts of a tree system are common to both. The analysis of different proportions of bark, sapwood, and heartwood made it possible to reveal: i) the rapid growth of Quercus pyrenaica gives rise to the formation of large proportion of heartwood in a few years; ii) Quercus petraea has the largest proportion of heartwood, but the studied trees are older and their growth is slower than the other species; iii) Quercus robur has an intermediate growth between the other two species. Therefore, our aim was to carry out a complete description of these parts of the wood, later, in upcoming work estimate their physical properties for use in cooperage industry.
The aim of this study was to investigate the components of volatile by-products released at different treatment temperatures. For this objective, the aldehydes and ketone were trapped in DNPH solution and the aldehyde and ketone derivatives were analyzed by HPLC. The acids and alcohols were trapped in deionized water and analyzed by HPLC and GC. The other volatile organic compounds were trapped on Tenax TA tubes and analyzed by GC-MS. The results showed that there was an increasing trend in the concentrations of aldehydes, acids, and alcohols with the increasing treatment temperature. The heat treatment at higher temperature resulted in more kinds of volatile organic compounds.
In this study, Turkish fir wood (Abies nordmanniana subsp. bornmulleriana) was subjected to two heat treatment process with varying temperatures (150, 180 and 200°C) and durations (2, 4 and 6 h). Some properties of the heat treated Turkish fir wood; mass change, water absorption, volumetric swelling, bending strength, modulus of elasticity (MOE), compression strength parallel to grain, color change and surface roughness have been tested and evaluated by statistical analysis. Consequently, volumetric swelling and water absorption values of the heat treated wood samples reducing. Bending strength, modulus of elasticity and compression strength parallel to grain values were decreased by heat treatment at high temperatures. Additionally, color change and surface roughness values of heat treated wood decreased with weathering compared to those of control samples.
To promote the environmentally friendly properties of wood plastic composites (WPC) fabricated via a polyvinyl chloride resin matrix, the effects of different amounts (0, 5, 15, 25, and 35 phr) of expoxidized soybean oil (ESO) on mechanical strengths, thermal stability, melting processing properties, and water absorption of the composite samples were studied. The results show that the tensile strength of WPC decreased. However, the elongation at break, water absorption and thickness swelling rates increased, especially for ESO addition amounts beyond 15 phr. The flexural strength and modulus of WPC followed an upward trend initially (at 5 phr ESO), then switching to a downward trend. The initial thermal stability at the first thermal decomposition stage and the melting processing temperature of the composites ewere effectively improved with the increase of ESO level. Compared to the samples without added ESO, the maximum thermal decomposition temperature (Tmax1 and Tmax2) values of the composites increased by 31°C and 8°C, respectively, while the melting processing temperature of the composites significantly decreased by 24°C corresponding to an added level of 35 phr. In summary, the WPC samples with 5-15 phr ESO addition not only effectively retained their the mechanical strengths and water absorption stability, but also improved their the thermal stability and melting processing properties.
The paper deals with the calculation and analysis of cutting force and input power when crosscut sawing with a chainsaw. For obtaining and evaluating the results, we have used empirical relationships and the values of appropriate coefficients given by the literature. After the evaluation we have gained the theoretical knowledge of the impact of a tree species and its moisture on cutting force intensity and input power. Tree species have a strong influence on cutting force; the harder the tree species is, the greater cutting force is required. Input cutting power is calculated from the cutting force that is why the impact of a tree species on input power is as big as on cutting force. It has been confirmed that the cutting force and cutting input power are affected by wood moisture content, as well.
The article presents calculation methods for flat-crush resistance (FCT) of honeycomb paperboard. The calculations were made on the bases of mechanical properties of the material that is, paper used for core production and shape of its cells. The methods presented in the article allow to calculate the FCT for the cores with the cells of the theoretical hexagon shape as well as of the real shape. The correctness of the methods proposed was verified by the comparison of calculation results with the results of FCT measurements for boards of different core height.
The relevant standards for glueline shear strength testing were summarized and analyzed in this paper. Depending on these existing test standards, the resulting stress in glueline is not pure shear stress, but a combination of shear and normal stresses. In order to overcome this deficiency, a symmetrical structure was proposed for making samples. Some comparative testing was accomplished by using these symmetrical samples, the results showed that the normal stress could be avoided during testing. These results were also confirmed by finite element method (FEM), the simulation results showed that the shear stress in glueline was uniform.