Treesearch

Gels made of cellulose nanofibrils (CNF) are biodegradable and renewable with numerous applications. Prior efforts to quantify rheological properties have considered the material primarily as a fluid and have been hindered by strain localization and sample size dependence.We identify important considerations in designing experiments to quantify the time-dependent mechanics of CNF gels and devise experimental methods to quantify the viscoelastic properties of CNF gels on time scales on the order of hours.Shearing experiments were designed using a custom-built loading device to apply uniform...

Wood anatomical information on 30 of the most common commercial species of wood in Colombia is presented as a set of edge-notched cards designed for field wood identification. Wood specimens from the xylaria in the Center for Wood Anatomy Research of the Forest Products Laboratory—the Madison Wood Collection (MADw) and the Samuel J. Record Memorial Wood Collection (SJRw)—were used as references for the descriptions and imaging. The cards present macroscopic anatomical characteristics—such as vessel distribution, parenchyma types, and ray size and arrangement—and images of similar or...

Connections in mass timber buildings degrade during fire due to charring and temperature-dependent material reduction, leading to significant fastener deformation. This study develops a temperature-dependent Beam-on-Foundation (BoF) formulation for CLT balloon-frame connections exposed to the WOODWISE large-scale compartment fire. The ambient-temperature BoF model was first validated against embedment and single-shear tests from the literature, followed by development and validation of a heat transfer model using thermocouple data from WOODWISE Test #3. The validated temperatures were...

Intumescent paints could be used in exterior applications and provide beneficial fire protection for structures located in wildfire-prone areas if the paints were more durable to weathering. A limited number of studies have evaluated the effectiveness of intumescent paints on wood post-weathering, and they have shown that the service life is relatively short, on the order of about one year. None of the previous studies assessed the effects of applying multiple coatings, including an acrylic latex color, bonding primer, and acrylic topcoat, over an intumescent paint. The effects of proper...

When wood is exposed to elevated temperatures (greater than 37 °C or 100 °F), its strength and stiffness can be degraded. The National Design Specifications for wood construction contain reduction factors for mechanical properties of wood and engineered wood used in these situations. These reduction factors were based on experiments where wood and engineered wood were conditioned at high temperatures. Since these experiments were conducted, adhesive formulations used in structural composite lumber have changed. This work compared strength properties of laminated veneer lumber made with...

A condition assessment of several glued-aminated timbers recently removed from service was conducted on the ends of the timbers using stress wave nondestructive evaluation techniques. After the assessment, toughness tests were performed in the laboratory on specimens obtained from the timbers to determine residual strength. Several areas of deterioration from decay were found during the nondestructive assessment. Deterioration was verified during subsequent toughness testing. A statistical relationship was found to exist between nondestructive test measurements and toughness test results.

Forests around the world serve a wide variety of functions, from providing habitats for many species to delivering economic benefits for communities. Conserving forests is often seen as a cost to commercial forestry in that removing land from production could reduce wood supply and jobs. Research led by scientists with the U.S. Department of Agriculture, Forest Service, however, shows that increased conservation may not necessarily come at a cost.A new study published in Nature Communications by researchers at the Forest Products Laboratory and the Southern Research Station, and their...

Consumer preferences are always changing, and wood species are not immune to those trends. Grain pattern, color, density, and other characteristics found in wood can play vital roles in how consumers decide which secondary wood products to purchase or, in the case of customized products, which species to select. This study investigated consumer perceptions of common and underutilized wood species available for use in secondary wood products, which addresses an evolving gap in understanding consumer decision-making. The research measured appearance-based evaluations of 10 different wood...

Hardwood lumber production in the United States reached a peak in 1999, with an estimated 12.6 billion board feet of output. However, the early 2000s ushered in a major structural shift – the large-scale offshoring of U.S. furniture manufacturing. Once the single largest user of hardwood lumber until the late 1970s, wood furniture has become the smallest major market for hardwood lumber today. As U.S. furniture production moved offshore, the industry shifted its focus toward housing and construction markets, which were entering a period of robust growth in the early 2000s. Sectors producing...

For the southern pines, interlocking stone cells (sclereids) are a fascinating periderm feature comprising only a small fraction of the outer bark (rhytidome), yet contributing greatly to its density/hardness. This study addresses the long-overdue need to carry out wet chemical analyses on periderm and obliterated phloem layers, the former herein limited to the stone cells. Extractives distributions by polarity were similar between loblolly pine ( Pinus taeda L.) periderm and wood samples; the total extractives content of the obliterated phloem was threefold higher. The claim that stone...