Metriguard's grain angle meter (Model 511) measures grain angle in wood by assessing permittivity. This study evaluates the correlations between grain angle meter readings and bending properties of 1,400 kiln-dried 2 by 4 specimens of southern pine (Pinus spp.) lumber and considers its utility for providing supplementary data for predicting the strength of lumber. The results showed that in mill-run lumber, the correlation between grain angle and modulus of rupture (MOR) was −0.420. In addition, in graded lumber, the correlation between grain angle and MOR got progressively stronger as the grade went down. With a few technical modifications, applying this device in a mill production setting could prove useful for supplementing other nondestructive methods for assessing bending strength in lumber.Abstract
Perspectives on Ash Wood Utilization and Marketing in Anticipation of Emerald Ash Borer in Minnesota
The emerald ash borer will likely impact over four million acres of Minnesota's forests in the next 10 years. This study surveyed forest products company representatives and other natural resource professionals to understand their perspectives on the current and future use of ash in wood markets. Survey respondents indicated they were only slightly optimistic that there will be new and emerging ash markets to support the large volume of ash wood potentially available in the next 10 years; however, new technologies such as torrefaction and heat treatments were noted as potential new markets for the species.Abstract
This study was conducted to investigate the hydrothermal softening characteristics of heartwood and sapwood from Catalpa bungei. The viscoelastic properties were investigated by dynamic mechanical analysis (DMA Q800) with a tension and submersion mode. Heartwood and sapwood specimens were tested under water-saturated conditions in the radial and tangential directions. The measured temperature ranged from 25°C to 79°C with three heating rates: 0.5°C/min, 1°C/min, and 2°C/min. The results show that heartwood specimens presented a higher storage modulus (E′) and a lower reduction of wood rigidity (ΔE′) than sapwood specimens. A difference was also observed in loss modulus (E″), and the glass transition temperature of lignin in heartwood specimens was nearly 2°C to 3°C lower than that in sapwood specimens. This could be caused by lower lignin content and higher levels of extractives of sapwood in comparison with heartwood. Additionally, a circular arc curve of E′ versus E″ was formed in heartwood specimens, irrespective of heating rate. These findings suggest that heartwood presented better hydrothermal softening characteristics than sapwood. Compared with the tangential specimens, the radial specimens revealed higher E′ and lower ΔE′, indicating that the radial specimens were less influenced by hydrothermal treatment.Abstract
The state-owned forestry enterprises (SOFEs) are important producers of forest products in China, and their competitiveness depends largely on their labor productivity (LP). This article is the first to investigate the sources of LP growth and the convergence patterns of SOFEs in northeast China. Based on panel data from 87 SOFEs in northeast China from 2006 to 2018, this article has used the Cobb-Douglas production function to analyze the sources of LP growth, using three convergent methods to explore convergence patterns. The results show that there is a positive correlation between LP and an SOFE's ability to compete, and that both total factor productivity and capital-to-labor ratio significantly contribute to LP growth in all SOFEs of northeast China; however, the role of the quantity of labor was negative. On the whole, all SOFEs did not have σ-convergence in LP growth, but an absolute and a conditional β-convergence. Although the LP divergence between SOFEs in northeast China has not been narrowed, there has been a “catch-up effect” in LP growth. These results can help people understand the laws pertaining to LP growth among forest enterprises and also how they may reduce production costs, improving market competitiveness among forest products.Abstract
The Internet is composed of more than 6.2 billion Web pages and grows larger every day. As the number of links and specialty subject areas grows, it becomes ever more difficult to find pertinent information. For some subject areas, special-purpose data crawlers continually search the Internet for specific information; examples include real estate, air travel, auto sales, and others. The use of such special-purpose data crawlers (i.e., targeted crawlers and knowledge databases) also allows the collection and analysis of agricultural and forestry data. Such single-purpose crawlers can search for hundreds of key words and use machine learning to determine if what is found is relevant. In this article, we examine the design and data return of such a specialty knowledge database and crawler system developed to find information related to cross-laminated timber (CLT). Our search engine uses intelligent software to locate and update pertinent references related to CLT as well as to categorize information with respect to common application and interest areas. At the time of this publication, the CLT knowledge database has cataloged nearly 3,000 publications regarding various aspects of CLT.Abstract
The objective of this study was to investigate the feasibility of using polyurethane (PU) foam waste obtained from automobile shredder residue (ASR) in plywood production. The PU foam waste from ASR was cleaned by water and acetone, ground into powder, dried, and mixed with polymeric diphenyl methane diisocyanate (pMDI) resin at various ratios (2.5%, 5%, 7.5%, and 10%, based on the weight of pMDI). The mixed adhesives were examined with Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis, and evaluated as plywood binders (measured in accordance with Chinese National Standard GB/T 17657-2013). The results indicated that the addition of PU powder into pMDI resin increased adhesive viscosity and efficiency, and also helped solve the problem of deficiency of pMDI on the veneer surface. FTIR results showed various reactions between pMDI and PU powder. This potential cross-linking might contribute to the cohesive strength of the cured adhesive. TG analysis results showed the possible increased thermal stability of the cured mixed adhesive at a temperature range of 150°C to 300°C. The best PU addition ratio was 7.5 percent of the pMDI weight, considering both the bond strength and production practice of plywood. Plywood testing showed that both the dry and wet bond strength reached the peak value at the optimal mixing ratio. The use of PU powder in plywood manufacturing provided a possible way of recycling PU foam waste while improving or maintaining the performance of plywood.Abstract
The objective of this study was to develop a performance-competitive bio-based hybrid resin system composed of methylene diphenyl diisocyanate (MDI) resin and novolac phenol-formaldehyde (PF) resin for engineered wood panel manufacturing. A novolac PF resin and a bio-oil–modified PF resin were blended with MDI at weight ratios of PF to MDI of 85:15, 75:25, 50:50, and 25:75, respectively. The obtained hybrid resins were examined with Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA), and evaluated as plywood binders. The results indicated that the gel times and viscosities of hybrid resins were closely related to the weight ratio of PF resin to MDI. At a ratio lower than 75:25, the viscosities of hybrid resins were appropriate for plywood application. FTIR results showed some reactions between the novolac PF resin and MDI. TGA results showed that reacting novolac PF resin with MDI resin possibly increased the thermal stabilities of hybrid resins in the temperature range of 150°C to 300°C. Panel performance tests showed that blending novolac PF resin with MDI increased both the dry and the wet bonding strength of panels at the optimal ratio of 50:50. Replacing phenol with bio-oil of the hybrid resin had the trend of reducing the hybrid resin gel time and increasing panel dry and wet bonding strength.Abstract
Development of moisture gradients within wood and wood-based composites can result in irreversible moisture-induced damage. Accelerated weathering (AW), generally employing harsh environmental conditions, is a common tool for assessing moisture durability of wood composite products. Use of milder AW conditions, such as cyclic changes in relative humidity (RH), may be of interest to the wood-based composites industry in assessing moisture durability under more realistic conditions. The primary objective of this study was to determine whether moisture profile development in oriented strand board and plywood during cyclic RH changes could be reasonably predicted with a simple moisture transport model, which may be practical for wood-based composite industry members seeking to develop new AW protocols. The diffusion model based on Fick's second law with empirically determined moisture transport parameters fits the experimental data reasonably well for the purpose of screening RH parameters.Abstract
The work presented here focuses on the, incorporation of an engineered polysaccharide polymer, α-1,3-glucan, derived from the enzymatic polymerization of sucrose, as a performance-enhancing additive for commercial, latex-based wood adhesives used in wood bonding applications. Adhesive performance was measured on hard maple (Acer saccharum) using ASTM Standard Method D-905. Dynamic mechanical analysis and solid-state nuclear magnetic resonance spectroscopy were the characterization techniques used to assess the properties of room-temperature–cured adhesive films. Significant increases in shear stress were observed for these formulated latex adhesives containing the polysaccharide polymer.Abstract
The effect of alkaline copper quaternary type D (ACQ-D) treatment on color retention, mold resistance, and surface physicochemical characterization of Neosinocalamus affinis bamboo was analyzed. The results showed that a treatment of 0.25 percent ACQ-D solution combined with pretreatment of potassium hydroxide and sodium dodecyl sulfate mixed aqueous solution can achieve a desired green color on the bamboo surface. The mold test result revealed that the treated bamboo samples had better mold resistance than samples only treated with a mold inhibitor. The thermogravimetric–Fourier-transform infrared spectroscopy analysis of the treated and the control samples indicated that the chemical structure of the surface was slightly modified, e.g., silicon was almost completely removed, which enhanced liquid permeability. The dilute ACQ-D solution combined with a proper pretreatment process could retain the favorable green color of bamboo and also improve mold resistance by slightly modifying the surface chemistry.Abstract
This research aimed to investigate the compressive fracture behavior and the compressive strength parallel to the grain in relation to moisture contents (MC) below and above the fiber saturation point (FSP) in Calamus simplicifolius cane. FSP of the rattan was investigated using a dynamic vapor sorption (DVS) apparatus, and the fracture behaviors of compression parallel to grain were analyzed by three-dimensional X-ray microcomputed tomography. The study indicated that the value of FSP derived from the DVS method was 25 percent. The average compressive strength parallel to the grain was found to be 39 MPa at 3 percent MC, 30 MPa at 10 percent MC, 17 MPa at 12 percent MC, 12 MPa at 27 percent MC, and 10 MPa at 45 percent MC. The strains of the yield and densification stage were prolonged with increasing MC, whereas the stress in the linear elastic stage decreased with increasing MC. The cracks of the rattan core and the deflection angle at higher MC were larger than that of low MC. Below the FSP, the compressive failure of the rattan showed a shear band oriented around 45° to the loading axis, and the surface was rough. Above the FSP, the rattan samples showed brooming failure. The interface among fiber bundles was delaminated and the fiber surface in the failure area was smooth. The fracture toughness of the rattan was higher than that of wood, which suggests that the rattan might be more suitable for modeling and curved materials.Abstract
Green building materials made from waste wood fiber have attracted worldwide attention. Poplar wood fiber can be molded into indoor partition wall brick with calcium hydroxide. The best process parameters are studied by single and multifactor methods. Compressive strength increases with the decreasing poplar wood fiber content and increasing calcium hydroxide content. The best process is 310 g of poplar wood fiber, 1,849 g of calcium hydroxide, and 10 minutes of cold press time. The mass proportion of poplar wood fiber and calcium hydroxide is 14:86. Compressive strength is affected extremely significantly by the interaction of poplar wood fiber mass, calcium hydroxide mass, and cold press time. It is affected significantly by the interaction between the calcium hydroxide mass and cold press time. The results are important to effectively use poplar wood fiber.Abstract
Maple and poplar are common names of species that grow in the eastern United States. Physical and mechanical properties were evaluated from small clear wood specimens of hard maple (Acer saccharum) and yellow poplar (Liriodendron tulipifera). Specific gravity, static bending strength and modulus of elasticity, compression parallel and perpendicular to grain, and Janka hardness were tested. The experiments were carried out on defect-free specimens extracted from boards supplied by members of the Staircase Manufacturers Association. The material was donated by companies located in the eastern United States. On the basis of the findings, it can be stated that mechanical properties for maple and yellow poplar have not changed substantially because the average values remain in a range that is very close to the values published in previous studies.Abstract
The performance of several wood surface treatments as well as a silica treatment claiming to provide protection against fungal decay and termite attack in aboveground applications were examined in termite, ground proximity, and sandwich tests at a subtropical site near Hilo, Hawaii. In general, the surface treatments performed similarly to untreated controls and provided little or no protection against fungal or insect attack. The silicate treatment provided some termite and decay protection, but fungal decay resulted in rapid declines in condition after 50 to 54 months of exposure. Copper azole–treated lumber provided the best performance against both termites and fungal attack, illustrating the benefits of pressure treatment over surface treatments in high-decay-hazard environments. These results also illustrate the importance of rigorous testing and standardization protocols for any product that makes durability claims before it enters the market to ensure that it will perform as expected.Abstract
It can be helpful for selected applications to improve the functionality of wood by compounding nano-metal materials with wood, endowing the wood surface with certain physical properties, for example, metallicity, electrical conductivity, and hydrophobicity. Therefore, in this study, a thin copper film was deposited on the surface of Pinus sylvestris L. var. mongholica Litv. veneer by magnetron sputtering. The film was applied at both room temperature and 200°C to obtain nano-copper–wood composites. The physical properties of wood-based nano-metal composites were characterized. The results indicated that the wood veneer metallization had no effect on the crystallization zone of wood; there were still wood cellulose characteristic peaks, but the intensity of the diffraction peak decreased. At the same time, there were characteristic diffraction peaks of copper. The mechanical properties of the wood veneer surface changed greatly; the surface of copper-plated wood veneer had good electrical conductivity and the wettability of the wood surface transformed from hydrophilic to hydrophobic. When the base temperature was 200°C, not only was the sheet resistance of the sample with coating time of 15 minutes about 4.6 times that of the sheet resistance of the sample at room temperature, but also the quality of the copper film on the wood surface was better than that at room temperature. The copper film was mainly composed of small particles with a compact arrangement.Abstract
Partial substitution of polymeric methylene diphenyl diisocyanate (pMDI) resin by 10 to 15 percent soy flour for the manufacture of strand board improves board properties while decreasing cost. For particleboard and medium-density fiberboard the soy-substituted resin performs as well as the control pMDI. The reaction of soy flour with pMDI occurs over several hours as tracked by CO2 evolution. The soy-amended resin must be used within about 30 minutes of formulation. Uniform mixing of soy flour with pMDI is critical because unreacted soy flour tends to retain water, which degrades the wet properties of the board. The soy flour increases the tack of pMDI resin, which increases the surface coverage and the relative bonded area at the glue line.Abstract
In this study, wood density, anatomical characteristics, and major chemical components were investigated on branchwood, trunkwood, and rootwood of three Alnus sibirica trees grown in Maoershan Mountain, Northeast China. The anatomical structure and composition of xylem within a tree were spatially heterogeneous. At the alpha = 0.05 level, the differences among branchwood, rootwood, and trunkwood were significant in wood density, cell dimensions, extractives, and ash content. The trunkwood was desired as papermaking raw material and structural timber because of its high-quality fibers, cellulose content, and medium density value. Because of its similar density to trunkwood, large-sized branchwood could be used as a substitute for structural materials. The rootwood with low densities and large vessel dimensions was suitable for producing short fiber biocomposite.Abstract
Wooden crossarms play a major role in supporting electric distribution lines in North America, but relatively few data exist on their condition as they age. The residual capacity of Douglas-fir crossarms in service in western Oregon for 45 to 60 years was investigated. Arms were sampled for residual preservative retention, the presence of visible decay fungi, and residual flexural properties; these results were then compared with three nondestructive tools. A majority of the arms tested had preservative levels well below those required for new arms, but only one decay fungus was isolated, and only five arms removed and dissected had any evidence of visible internal decay. Moduli of rupture for the arms were generally below the minimum levels required by national standards, but most still retained at least 67 percent of this value. Nondestructive evaluation tools were generally poorly correlated with flexural properties, possibly because of the heavily weathered and checked exterior condition.Abstract
The objective of this article is to evaluate the relationship between the dynamic modulus of elasticity (MOEd), which was obtained with acoustic-based nondestructive testing (NDT) methods, and static bending properties of two domestic hardwood oak species. The mechanical properties were conducted using static modulus of elasticity (MOE) and modulus of rupture (MOR) in radial and tangential directions. Mechanical tests were performed according to ASTM D143 on small clear, defect-free specimens from the two tree species: red oak (Quercus rubra) and white oak (Quercus alba). The MOEd was determined by two NDT methods and three longitudinal vibration methods based on the fast Fourier transform. The destructive strength values obtained in this study were within the expected range for these species. The MOE was best predicted by NDT methods for both species but also had a strong capability to predict MOR.Abstract