Soy flour was evaluated as a partial substitute for resin in the manufacture of oriented strand board (OSB), a wood-based composite that often replaces solid lumber and plywood in structural applications in the construction industry. Since the presence of soy could alter OSB biodegradation properties, termite resistance of OSB panels made with 0, 10, and 20 percent of polymeric methylene diphenyl diisocyanate (pMDI) resin substituted with soy flour (OSB0, OSB10, and OSB20, respectively) was investigated. Single choice tests between three types of OSB and southern yellow pine (SYP) solid wood and an OSB choice test (OSB0 vs. OSB10) were evaluated. Results indicated that termites always showed a preference for SYP, with the OSB becoming less palatable when soy flour was present. Percentage weight losses for OSB0, OSB10, and OSB20 were 5.7×, 8.4×, and 8.6× less, respectively, compared with SYP. In the absence of SYP, termites did not differentiate OSB0 from OSB10, with OSB10 showing 1.5× less weight loss compared with OSB0. Visual rating data supported weight loss data, except significantly less damage was only found when the choice paired SYP with OSB made with soy (OSB10 or OSB20). Termite consumption preference for SYP was explained by differences in water absorption kinetics. SYP reached saturation (105% moisture content) within 1 week on moist sand, while moisture content of OSB composites slowly climbed to 79 percent over 4 weeks, never reaching a plateau. Lower moisture content was due to the presence of water-repellent resin and wax in the OSB.Abstract
Sticker stain is a material defect that results from moisture migration during wood drying, often spoiling the appearance of the surface of wood products. The effect of drying temperatures on the occurrence of surface sticker stain was investigated using Japanese cedar (Cryptomeria japonica D. Don) and three types of stickers (air-dried Japanese cedar, aluminum, and stainless steel) under four drying temperatures (20°C, 50°C, 75°C, and 100°C). At lower drying temperatures, the air-dried wood sticker tended to suppress the occurrence of surface sticker stains, whereas higher temperature or metal stickers produced sticker stains with deep color. However, no definitive relation was shown between the initial moisture content and the extent of sticker stain with deep color regardless of drying temperatures. It was considered that the partial delay of drying happened around the contact area with stickers, especially in cases of metal stickers. It was also found that the use of metal stickers at higher drying temperatures induced depressions in Fourier transform infrared spectra related to the occurrence of hygrothermal conditions.Abstract
In 1990, Europe, North America, and the Asian democracies of Japan, Taiwan, and South Korea (JTK) were the major export markets for U.S. hardwood lumber and oak species accounted for 59 percent of total exports. In the 1990s, shipments to Europe and North America increased, while shipments to JTK declined. During the early 2000s, exports to China and Vietnam (CHV) increased. The worldwide recession of 2009 caused exports to decline in all regions, and oak species accounted for 37 percent of total shipments that year. Since 2010, CHV has become the most important export market for all species except maple. In 2020, oak species accounted for 43 percent of total export volume, and walnut ranked third in value of shipments. An examination of imputed prices found that exports tend to be composed of mid- to higher-quality hardwood lumber. Since 1997, real prices of exported lumber have declined for most species, and this decline occurred concurrently with increased U.S. sawtimber volume. In the 1990s, increased exports expanded the market for domestically produced hardwood lumber. Since the early 2000s, increased lumber exports have partially countered reduced domestic demand and have acted as a hedge against greater declines in overall demand for U.S. hardwood lumber.Abstract
Flame-retardant reed inorganic particleboard was prepared by hot-pressing with reed particles as a reinforcing material and using magnesite cement as an inorganic adhesive. The effects of inorganic sizing amount, density, and hot-pressing temperature and time on the properties of reed inorganic particleboard were investigated by orthogonal testing. Particleboard properties were tested and characterized by means of a universal mechanical testing machine, scanning electronic microscopy (SEM), X-ray diffraction (XRD), and cone calorimetry. The results showed that the mechanical properties of particleboard prepared under conditions of 60 percent sizing capacity, 100°C hot-pressing temperature, 15 minutes hot-pressing time, and 1.2 g/cm3 density were the best, reaching the national standard for cement particleboard. At 60 percent sizing, the characteristic peak value of inorganic adhesive hydrate crystal phase was the largest, the crystallization area dense and orderly, and the coating effect on shavings good; these attributes confirmed the trend of mechanical properties of reed shavings board increasing with sizing amount. Thus, the sizing amount had a significant influence on flame retardancy and smoke suppression performance of this particleboard. With an increased application amount, the heat release and total heat release rates of the particleboard and total smoke generation rate showed decreasing trends. Additionally, when the ignition time was delayed, the flame retardancy and smoke suppression performance of the particleboard was enhanced.Abstract
When discussing structural southern yellow pine lumber, questions frequently are asked regarding changes over time. This is a significant area of discussion given that structural lumber properties (i.e., design values) were changed around 2012. Climate change, forest management, genetics, processing, and others are listed among the many possible contributing factors. Of interest are these questions: (1) Are changes in bending properties permanent at some fundamental level, or are they somewhat dynamic and responsive to controllable factors? (2) To what degree have the basic southern pine wood mechanical properties changed over time? Related thereto, this research examines the bending properties of small clear pine specimens from three samples. Sample 1 was pulled from a production-weighted sample of in-grade parent lumber. Sample 2 was pulled from commercially available molding and millwork. Sample 3 was pulled from data from the U.S. Department of Agriculture Forestry Products Laboratory from the early to mid-1960s. The flexural properties of small clear specimens among the three samples showed some statistically significant differences. However, there was no clear trend regarding these differences. These results appear to support the notion that while the variability of pine's flexural properties is significant and that while many changes in forest management and production have occurred over the past five decades, the basic density and bending strength of clear southern pine appear generally stable over time.Abstract
Southern yellow pine (SYP) is one of the most used softwood species in the world. Most of this raw material come from fast-grown plantation trees. It is of interest to determine if SYP clear wood properties may have changed over the long term, in particular whether such properties may have declined. Herein, specific gravity (SG), ultimate compression strength parallel to grain (UCS‖), and UCS perpendicular to grain (UCS⊥) from three samples were compared: Sample 1 tested in 2014; Sample 2 from molding and millwork producers tested in 2017–2019; and Sample 3 from a study conducted in the mid-1960s. With respect to specific gravity (SG), the wood in Sample 1 was significantly lower than that from Samples 2 and 3. With respect to UCS‖, all three samples were statistically different. Adjusting to 12 percent moisture content had no influence on the mean separation of UCS‖. With respect to UCS⊥, no statistically significant differences were detected among the test data from any of the three samples. However, for the UCS data generated from the SG and moisture content–related model, Sample 2 was higher than Sample 3, and Sample 3 was higher than Sample 1, and these differences were statistically significant. Overall, these findings do not suggest that broad or consistent changes or declines of these wood strength properties have occurred during the past five decades.Abstract
Moso bamboo (Phyllostachys edulis), an apt example of an anisotropic, functionally graded composite material, is the most important commercial bamboo species of China. This species has excellent mechanical properties due to its unique vascular bundle structure. This article examines the variation in mechanical properties of single vascular bundles with respect to their location within a bamboo culm. The mechanical exfoliation method was used to prepare the single vascular bundle. This study found that moso bamboo has superior stiffness and strength. Additionally, the variation in properties was large in the radial direction but minimal in longitudinal direction. The large variation in mechanical properties of vascular bundles can be ascribed to the synergistic effect of the fibrous sheath and parenchyma rather than to changes in fibrous sheath properties. This study provides a basis for the structure application for moso bamboo.Abstract
This study investigates the properties of Lonchocarpus sericeus to determine its potential use for timber. Three matured trees of L. sericeus were selected from a forest located in Longe Village, Oluyole Local Government Area in Oyo State, Nigeria. Discs from the harvested trees were collected at the base (10%), middle (50%), and top (90%) and further partitioned into inner wood, center wood, and outer wood. An investigation was carried out to characterize the wood age, density, shrinkage, impact strength, modulus of elasticity, modulus of rupture, compressive, and shear strength. The ages were 28, 29 and 32 years. The mean wood density at 12 percent moisture content was 836.63 kg/m3, which shows that it belongs to the high-density wood category. The mean shrinkage values in the radial, tangential, and longitudinal directions were 2.50, 3.99, and 0.78 percent respectively; the volumetric shrinkage was 6.36 percent. These shrinkage values were indicative of good dimensional stability. The mean impact bending strength, modulus of rupture, modulus of elasticity, maximum shear strength parallel to grain, and maximum compression strength parallel to the grain were 24.14, 114.18, 11,276, 12.76, and 47.16 N/mm2, respectively. End-use assessments suggest that the wood species can be used in similar applications as well-known timbers. The study found L. sericeus to be very dense with high strength in comparison to well-known timbers. It was observed that the mechanical properties of the species decrease from the base to the top and also increase from the outer wood to the core wood.Abstract
Companies in the construction industry have a wide range of suppliers to choose from to meet their building material needs. Local (in-state) suppliers within key southern states in the United States face challenges gaining market share within the construction sectors. Construction companies often outsource their purchase of wood products from a different state or country, which adversely affects the local economy as a result of loss of revenue. However, if companies were limited to in-state supply it would affect trade across states and countries; but the focus was to improve local wood products supplier market impact. Companies within the states of Georgia, Texas, Oklahoma, South Carolina, Florida, and Virginia were interviewed by phone and in person to determine how companies chose wood product suppliers and what factors affected their purchasing decisions. Key factors included cost, quality, delivery, flexibility, location, relationship, and payment options. A survey of construction companies was conducted after the interviews were concluded. Important factors highlighted by responses included cost, quality, relationship, and lead time in choosing a supplier. Suppliers were asked to differentiate their products using information the construction companies highlighted as factors they emphasized. In-state wood product suppliers have an opportunity to gain market share within the construction industry using the factors those construction companies favored in interviews and survey results.Abstract
The objective of this study was to investigate the lab-scale manufacturing process of insulation fiberboard (IFB) with cellulose nanofibers (CNFs) and evaluate the effects of CNFs on the mechanical and physical properties of the IFB. Because the fabricated IFBs with CNFs had a homogeneous appearance, it was assumed that CNFs can be easily dispersed within IFB by adding them during the mixing stage of the wet process of wood-based board production. The results for the IFBs with CNFs revealed that the density and bending properties increased, while the thickness decreased with an increase in the CNF addition ratio. Furthermore, after the water absorption test, the weight change rates of the IFBs decreased, and the thickness swelling rates increased. Although the size of the specimens was different from the size in JIS A 5905 (Japan Standards Association 2014), the modulus of rupture (MOR) values of IFBs with a target density more than or equal to 0.20 g/cm3 were higher than the value of A-class IFB in the standard for all CNF addition ratios. In addition, lower thermal conductivity may be realized under similar MOR values by adding CNFs to IFB. On the other hand, to produce CNF-reinforced IFBs with target density/thickness, it is necessary to develop a method for decreasing the cohesive force derived from CNF aggregation and the compressive force originating from the water surface tension caused by the high water retention of CNFs.Abstract
To investigate the decay extent of wooden components in the ancient buildings of Danxia Temple, the absorption peak intensities, changes in chemical components, and cellulose crystallinity of red oak (Quercus sp.), birch (Betula sp.), and maple (Pterocarya sp.) wooden components were determined and analyzed using Fourier-transform infrared spectroscopy. The results are as follows: (1) The absorption peak intensities representing cellulose and hemicellulose decreased or disappeared obviously in the decayed red oak wood (DROW); on the contrary, those representing lignin increased. The indexes of the content of cellulose, hemicellulose, and cellulose crystallinity also decreased; on the contrary, those of the content of lignin increased. Those results indicated that cellulose and hemicellulose in DROW were largely degraded by brown-rot fungi. (2) The absorption peak intensities representing cellulose and hemicellulose decreased both in the decayed birch wood (DBW) and the decayed maple wood (DMW), whereas those representing lignin increased. The indexes of the content of cellulose, hemicellulose, and cellulose crystallinity also decreased, whereas those of lignin increased. Those results showed that cellulose and hemicellulose in DBW and DMW were seriously harmed not only by insects but also by brown-rot fungi. By comparison, the extent of fungal damage was lower in DMW than in DBW.Abstract
Interest in cellulose nanocrystal (CNC) recently has been growing significantly. Many applications have been developed for CNC and appropriate procedures to handle the CNC suspensions are critical for these applications. In this study, we explored a method evaluating CNC suspensions based on rheological property characterization. We used a rotational viscometer to characterize CNC suspensions at concentrations of 3, 4, 5, and 6 wt.%. We collected primary readings from the rotational viscometer, including spindle rotation speed and torque, to generate apparent viscosity and shear rate for CNC suspensions. We applied three different methods summarized from the literature to calculate apparent viscosity and real shear rate. We critically analyzed differences among calculation results from the three methods. Shearing thinning behaviors obeyed the power law flow model for all CNC suspensions in the shear rate tested. At different concentrations, consistency and flow behavior indices in the model differed in the measured shear rate range. With the same shear rate, higher concentration CNC suspension had a higher apparent viscosity. The apparent viscosity of the CNC suspension was associated with its weight concentration in a power law relationship. This study indicated that a rotational viscometer can be used as a quality control tool for characterizing the rheological properties of the CNC suspensions. We made recommendations for using appropriate calculation methods to obtain shear rate and apparent viscosity of CNC suspensions from the primary readings of a rotational viscometer under different situations.Abstract