Wood and Fiber Science (E-Journal)
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Time-temperature effects on early-stage primary thermal creep of plywood and oriented strand board (OSB) at elevated temperatures
Full text linkThis study examined the effects of elevated temperatures on plywood and Oriented Strand Board (OSB) subjected to a constant load. Due to the short duration and the absence of a steady-state, this behavior was classified as "Early-Stage Primary Thermal Creep." Deflections at each elevated temperature, ranging from 120°C to 200°C, were analyzed to assess the thermal effects. Statistical analysis of the maximum deflections indicated the onset of thermal degradation at around 170°C for both plywood and OSB. Notably, a significant increase in deflection was observed between 180°C and 190°C for OSB, suggesting adhesive thermal decay. In addition to the statistical analysis, a numerical model was fitted to the experimental data to create temperature-dependent deflection curves, revealing an exponential trend. To understand the combined effects of temperature and time on early-stage primary thermal creep, two models were evaluated: a modified rational function model and a modified power model. The temperature-dependent power-exponential creep model provided a superior fit for both plywood and OSB, as indicated by higher R² values and lower root mean square errors
A survey of woods for acoustic guitar soundboards
No full textThe soundboards of guitars have been crafted from wood since the beginning of string instruments. Based on industry-specific criteria, soundboards have traditionally been made from spruce and a few selected tropical wood species. This paper aims to find potential U.S. hardwoods that can serve as viable options to supplement the current manufacturing needs of the guitar industry. This paper also identifies the properties within the industry-specific criteria and determines how each property contributed to the market success of the soundboard woods used in production. The woods were separated into spruces, other woods in production, and U.S. hardwoods. A decision matrix determined which U.S. hardwoods would make viable options for production-grade soundboards. Basswood has the most promise of being a supplemental option
Drying Ochroma pyramidale from Costa Rican plantations using kiln, solar and air drying: time, moisture content, color and drying defects
No full textBalsa (Ochroma pyramidale) holds significant market importance due to its rapid growth and the low density (<0.2 g/cm³) of its wood. Extensive areas of balsa have been established in many tropical regions; however, knowledge about drying wood from this species remains limited. This study evaluated kiln drying (KD), solar drying (SD), and air drying (AD)—in terms of drying time, wood color, and the presence of defects such as warp, splits, and cracks—of 6-cm-thick lumber from 1.7- and 4.5-year-old balsa plantations in Costa Rica. Drying time was shortest for KD, while SD required an intermediate duration between KD and AD. Balsa wood dried using KD exhibited statistically significant differences in all three color parameters, with the highest overall color change. Conversely, wood dried using SD and AD displayed similar values for the three color parameters, with minimal color change. Boards exhibited varying levels of warping (crook, bow, cup, and twist), splits, and checking before drying. SD resulted in similar defect levels (incidence, magnitude, and quality index) to AD. However, KD caused the greatest changes in wood quality and the highest defect incidence. While KD allowed for drying balsa wood with fewer defects in the shortest time, the highest wood quality was achieved with SD and AD, albeit requiring longer drying durations
Printability and mechanical properties of wood resin polymer composites manufactured using stereolithography
Full text linkWood polymer composites (WPC) fabrication using stereolithography has received little attention. WPC research has been mostly directed to traditional manufacturing methods and fused deposition modeling. Stereolithography offers better print precision, structural accuracy, and ease of production than other 3D printing methods and directly creates the final wood polymer composite. Typically, WPCs fabricated using traditional methods used 40-60% wood in the mixture; however, the highest ratio used with stereolithography has been 10%. Increased wood content reduces costs and creates a product that more closely resembles the mechanical properties of wood. This study focused on increasing the wood flour ratio of WPC printed using stereolithography beyond 10% while studying the factors influencing printability and the mechanical properties of the printed materials. A blend of maple and oak wood flour was combined with methacrylate-based resin at wood levels of 2.5, 5, 7.5, 10, 12.5, 15, and 17.5 wt. % to fabricate the wood polymer composite. The highest ratio of wood flour successfully printed in this study was 17.5 wt.%. This paper discusses the tensile and compressive behaviors of the WPC, as well as the dimensional accuracy of the stereolithography process for higher wood ratio WPC fabrication. The process of fabrication, post processing, success and failure in printing, and characterization of print defects were also studied. Stereolithography can be used to manufacture wood polymer composites in a direct production method at higher wood flour ratios, and improving the capability of the method holds the potential to increase access to a sustainable substitute for conventional wood for various uses
The impact of water exposure on the mechanical properties of a wood-plastic composite
Full text linkProcessed and unprocessed polypropylene samples reinforced with various proportions of pine and beech wood were manufactured using pressure molding and subjected to various mechanical tests. Increasing the percentage of wood particles regardless of the wood species was associated with increased density and hardness of the wood-plastic composite, while tensile strength, deformation at fracture, and elastic limit decreased with increasing particle size. Higher moisture contents were associated with increases in both tensile strength and elastic limit
Correlation between non-destructive assessment of wood veneers and the resulting laminated veneer lumber
Full text linkThis study investigated correlations between the mechanical properties of individual red maple (Acer rubrum) veneers and that of associated laminated veneer lumber (LVL). Veneers with an average thickness of 3.5 mm, width of 304 mm, and length of 2.44 m, were first subjected to a nondestructive test (NDT) using stress wave analysis. Dynamic modulus of elasticity (MOEd) was used to classify 480 veneers into four equal groups: high-grade, medium-grade, low-grade, and a mixed group. Each LVL consisted of 12 veneers bonded with polyurethane (PUR) adhesive. All LVL billets were evaluated nondestructively to determine their dynamic modulus of elasticity. Two different measurement systems were employed: a Fakopp Microsecond Timer was used for a time-of-flight approach and a Hitman HM200 (resonance acoustics approach) applied the longitudinal stress wave method and assessed its reliability for predicting the mechanical performance of LVL billets. A strong correlation (r = 0.85 and R2 = 0.73) was found between the average MOEdVeneer of veneers and that of the LVL billets (MOEdLVL). There was a strong correlation between MOEd from the Hitman HM200 device (MOEdHitman) and that from the Fakopp device (MOEdFakopp) (r = 0.93 and R2 = 0.86)
Near-infrared spectral signatures differentiate blue stain and brown rot fungi in conifer and broadleaf trees
Full text linkColonization by blue stain and brown rot fungi affects timber quality in distinct ways. Blue stain fungi cause discoloration without reducing wood properties, while brown rot fungi degrade wood tissues, resulting in brittleness and brown coloration. Given these chemical differences, we investigated whether near-infrared spectroscopy (NIRS) could distinguish between these fungal types. We hypothesized that early fungal attack would produce unique spectral signatures, allowing for rapid identification. Wood disc samples were collected from white spruce, lodgepole pine, and trembling aspen in Fox Creek, northwest Alberta, Canada, ca. 4 months after a wildfire. The trees were colonized by fungi associated with blue and brown sapwood discoloration and analyzed using NIRS. In white spruce, we found consistent and significant absorbance differences between blue- and brown-discolored sapwood across each 100 nm segment. In lodgepole pine, the most distinct differences occurred in the 1650–1750 nm, 2050–2150 nm, and 2350–2450 nm ranges. For trembling aspen, differences were evident across most 100 nm intervals, except 2150–2250 nm. Permutational multivariate analysis of variance (PERMANOVA) indicated greater spectral dissimilarity between fungal types in white spruce and trembling aspen, with less pronounced differences in lodgepole pine. Our findings suggest that NIRS can effectively classify fungal-discolored wood in white spruce and trembling aspen within the first year following wildfire. However, its application to lodgepole pine in the same timeframe may be less reliable
Spatiotemporal dynamics of termite infestation in urban Araucaria cunninghamii: A case study in Taipei
Full text linkTermite feeding on the trunk cross-sections of Araucaria cunninghamii in Taipei, Taiwan, was examined using 2D stress wave imaging (FAKOPP system). Six inspections were conducted at 2-month intervals to monitor six trees. 2D cross-sectional stress wave velocity images were created at different heights (30–180 cm) to assess termite feeding damage. Termite damage, quantified as damage ratio (DR, %), ranged from 0% to 55% across different trees and heights, with maximum increases of up to 21% in DR observed over a 2-month period. In the investigated cases, termites primarily fed on the interior of tree trunks. The feeding pattern typically extended longitudinally, then proceeded in a tangential (circular) direction, and finally moved radially. This study identified Coptotermes formosanus as a key termite species involved. Typically, termites prioritized feeding on the earlywood over the latewood. The periods with the highest damage to trunk cross-sections due to termite feeding occurred during seasons with higher temperatures and relative humidity. Damage initially appeared near the heartwood or the boundary between the heartwood and sapwood, gradually expanding into the heartwood. Of the six trees monitored for the full study duration (after one tree was felled for validation), subterranean termite tunneling was observed as the primary pattern in three trees, while aerial swarm invasion patterns were inferred for two trees based on initial damage locations
Wood Properties of Four Tropical Species from Mining Areas in the Amazon, Brazil Part 1: Anatomical Characterization: Wood Properties of Tropical Species from the Amazon
No full textVegetation suppression is a common activity in mining areas, and it generates large volumes of discharged logs from excavation activity. In most cases, these logs are stacked and stored in open-air yards, as a result, the material is exposed to conditions that favor the degradation process. Mining activities have a significant impact on the surrounding environment and ecosystem, but most of these changes are not yet understood, especially the changes that can occur in wood properties. Thus, the goal of this article (Part 1) was to characterize the anatomical features of tropical species stored in mining areas. Wood samples were identified and collected during five different exposure periods (0, 1, 4, 6, and 8 years of exposure). The species identified and studied were Jacaranda copaia, Astronium lecointei, Caryocar villosum, and Protium altissimum. Three logs were collected from each species and each year of exposure, totaling 54 specimens used for the anatomical analysis of the microstructure of the species studied. Variations in the cellular dimensions of the anatomical structures were observed but without a pattern of increase or decrease in relation to storage time. Degradation signs were also observed in some species, and Jacaranda copaia, a lower-density species, showed higher levels of degradation
