Volume 13 Issue 1

Strength attributes of isolated microscopic sections of earlywood (EW) and latewood (LW) tissues are evaluated for sessile oak (Quercus petraea). The properties measured at the micro-scale were then used to estimate the macroscopic strength characteristics of the wood. The bending strength, modulus of elasticity (MOE) in bending, and tensile strength of EW and LW sections were determined. The EW and LW ring width, annual ring width, and LW proportion were also determined. The estimated values were calculated using the EW and LW mechanical properties and LW proportions, while the measured values were determined using standard-sized test samples. The LW sections had higher values than the EW sections for all measured mechanical properties. The average EW and LW widths and LW proportion were 0.50 mm, 0.49 mm, and 49.3%, respectively. The estimated bending strength, MOE, and tensile strength values were 80.1 MPa, 2831.7 MPa, and 112.1 MPa, respectively. The estimated bending strength and MOE values were lower than the measured values, while the estimated tensile strength values were higher than the measured values.

Lignocellulosic biomass is one of the most abundant raw materials available on earth, and the study of lignocellulose components is required for the production of second-generation biofuels. Fourier transform infrared spectroscopy (FTIR) has a demonstrated potential as a cost-effective and efficient method to distinguish between lignocellulose specimens. This study compared three FTIR modes—attenuated total reflectance (ATR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and Transmission-FTIR—in their ability to distinguish samples of different lignocellulose species at varying grain sizes, as well as before and after enzyme treatment. The reproducibility among replicates and the separation between different sample groups was assessed using an adjusted “separation/scatter” metric calculated from the scores of principal component analysis (PCA). Attenuated total reflectance was most frequently the best method due to its least amount of variance among sample replicates. However, Transmission-FTIR was better than ATR for certain particle sizes or enzyme treatments. Diffuse reflectance infrared Fourier transform spectroscopy was repeatedly inferior to ATR and Transmission-FTIR, especially in terms of variability. This work provided insight into the best mode of FTIR for characterizing lignocellulose powders. Future work should test the robustness of these results with a wider range of wood species, particle sizes, enzymes concentrations, and reaction conditions.

Changes are reported in perpendicular and parallel glossiness, lightness (L*), red colour (a*) tone, and yellow colour (b*) tone due to thermal aging in beech (Fagus orientalis Lipsky), maple (Acer pseudoplatanus L.), northern red oak (Quercus rubra L.), American black walnut (Juglans nigra L.), and walnut (Juglans regia L.) wood coated with a UV system commonly used on laminated parquets. Coated samples were exposed to different thermal aging levels (30 °C for 30 days, 60 °C for 60 days, and 90 °C for 90 days). Colour and gloss were determined before and after the thermal aging processes. The L* decreased for all species with the thermal aging decreasing more for more intense processes. Variations of the a* and b* colour parameters depended on the species. The colour parameters changed for temperatures higher than 30 °C. In general, glossiness decreased proportionally to the severity of the thermal aging for all of the species studied.

This work conducted market research on the use of smartphones and smartphone applications (apps) in the forest products industry and academia. Scholarly literature was reviewed, and related apps were considered. An online survey was conducted to collect data adopting a convenience sampling method. Participants were individuals who work with wood or wood-based products. The sample was compiled from publicly available online and offline sources. A questionnaire was specifically developed for this study. Out of 1,221 email invitations, 311 responses were returned at the response rate of 27.2%. Descriptive statistics and analysis of variance were used for analysis. Nearly all of the respondents (95.7%) had smartphones, and over half of them were iOS users (52.3%). A higher personal use, as compared to work use, of smartphone apps was observed. Respondents of Millennials and Generation X indicated higher personal app use than Baby Boomers. Academia and research users showed higher app uses. More respondents had purchased paid apps (45.2%) than in-app services on free apps (28.5%). This finding indicates that paid apps may be of more interest to respondents than in-app purchases.

Archaeological wooden artifacts are buried in wet environments, leading to water absorption and waterlogged wood. In order to conserve these wooden cultural heritage items, dehydration and consolidation are critical steps. This study used nontoxic ε-caprolactone (CL) as the dehydration agent to replace the water in the simulated waterlogged wooden structures, inserting the poly(ε-caprolactone) (PCL) into the wood cell walls by oxalic acid catalysed CL ring-opening polymerization (ROP). The mechanical and chemical performance of the untreated and treated wood was evaluated. The weight gain percentage and dimensional stability of the treated wood were significantly improved. The polyester chains within the cell wall structures were analyzed by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA-DTA), and scanning electron microscopy (SEM). FT-IR showed that the intensity of hydroxyl (-OH) absorption peaks decreased, and carbonyl (C=O) peaks attributed to the PCL addition were observed. Thermal analysis revealed that the degradation of PCL polymers was faster than that of wood components. The morphology characterization demonstrated that the treated wood was bulked with the PCL polymers.

The selective biodegradation of grape pomace tannins was studied using Aspergillus niger strains. The conditions were optimized in terms of monomeric catechin production. The optimal degradation conditions were: 10.0 g·L-1 of tannins in the induced medium, pH 6.5, and cultured on a shaking table at a rate of 120 r·min-1 at 28 °C for 36 h. The biodegraded tannins were used to partially substitute for phenol-formaldehyde in adhesive formulations. The biodegradation enabled the production of adhesives and wood panels with better properties (lower resin viscosity, higher internal bond strength, and lower thickness swelling). A particleboard in which the resin contained 60% biodegraded grape tannins displayed good performances (IBdry = 0.46 MPa, IBwet = 0.15 MPa) and passed the standard specifications for dry and wet conditions.

This study investigated two classifications of wood cellulose of particle sizes 300 µm to 424 µm and 600 µm to 849 µm. The cellulose samples were characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). The cellulose crystal revealed a preferred orientation along the (200) plane for the most prominent peak. The XRD diffractogram revealed an orthorhombic structure obtained from the powder diffractogram file (PDF). Furthermore, the crystallinity index and crystalline size were calculated and the increase in crystalline size of the isolated cellulose indicated higher thermal stability. The EDX analysis showed chemical components of carbon (C), sodium (Na), chlorine (Cl), and oxygen (O) in the isolated cellulose. The morphology of the cellulose appeared as strings of fibres. The isolated cellulose has applications in the production of biomaterial, thermal insulating devices, and domestic applications.

To perform a non-destructive evaluation of wood, the Christoffel equation is frequently used to describe the relationship between the ultrasonic wave velocity and the mechanical parameters. In the context of acoustical tomography imaging of standing trees, the key contribution of this numerical study is to determine the influence of mechanical parameters of the wood radial-tangential plane on the wave velocity computation using the Christoffel equation. Mechanical parameters from six species were selected. A sensitivity analysis was carried out by increasing and decreasing every parameter by a given percentage, and then by computing the variation of velocity for a set of wave direction of propagations. The evolution of the wave velocity, according to the direction of propagation, depended on the considered species; there was a difference between the softwoods and the hardwoods. The sensitivity analysis showed a bigger influence of the Young’s moduli, followed by the Poisson’s ratio, and finally by the shear modulus. However, these last two parameters cannot be neglected when using the Christoffel equation to solve the inverse problem of standing tree tomography. A proposed solution involves determining the propagation paths using the Young’s moduli as variables and then inversing the set of equations in accordance with the overall parameters.

This research aimed to develop economical, high-performance acoustic oil palm boards (OPB) using the convection (CV) and microwave (MW) wood drying technologies under variable thermal conditions. The results revealed that the CV and MW oven temperatures were positively correlated with moisture desorption but inversely correlated with drying time. The CV heating temperatures were inversely and positively correlated with the density and volumetric shrinkage, respectively, and the MW power output was positively correlated with density and shrinkage. Thus, the MW-treated OPB specimens exhibited stronger mechanical characteristics than the CV-treated OPB specimens. Importantly, the CV-treated OPB specimens acoustically outperformed the MW-treated counterparts, as evidenced by the former’s higher noise reduction coefficients (NRC). This phenomenon was attributed to the abundance of fissures between the vascular bundles and the parenchyma. Thus, the CV technology was more operationally and economically suited to the high-performance acoustic OPB.

The present work studied the numerical modelling of heat transfer in a pile of Pinus radiata samples of a square cross-section by using radio frequency heating.  More precisely, the study focused on the effects of the energy transferred to a dielectric material (wood) from an electromagnetic field, which required the calculation of the dielectric loss factor and its correlation with conservative equations. In this way, the temperature distribution across Pinus radiata samples was obtained through the integration of the energy equation using the finite volume method. The numerical results were compared to experimental data obtained from three experiments of radio-frequency heating of wood samples of a cross-sectional area of 4 in × 4 in, 3.1-m-long, and 20 cm of separation between plates. According to the observed linear behavior of the heat transfer process, the numerical results of the transient variation of temperature were in agreement with the experimental data.