Treesearch

Combined heat and moisture transfer modeling is used in building envelope analysis to identify potential moisture durability risks. Moisture transfer in porous materials is typically partitioned into liquid transport and vapor diffusion. Although modeling approaches differ in complexity, coefficients for liquid transport are often derived from laboratory measurements of water absorption by partial immersion. Models generally include the assumption that capillary transport is dominant during the measurement, while vapor diffusion is negligible. This is reasonable for mineral-based materials,...

In August, the Federal Reserve Board of Governor’s focus for a "housing reset" was in full force. Month-over-month data continued a negative movement in many data categories. Year-over-year data were similar. Single-family permits decreased again, which foreshadows further moderation in single-family activity in the forthcoming months. The impact of increasing borrowing costs, slow income growth, and still-elevated house prices have resulted in a major obstacle for new and existing house sales. The number of potential buyers is dwindling quickly, and first-time buyers also are being...

Soy flour dispersions are used as adhesives for bonding interior wood laminates, but the high viscosity of these dispersions requires low solids in the adhesive formulations; the greater water content causes excessive steam pressure during hot press manufacturing. This limits the utility of soy adhesives in replacing urea–formaldehyde adhesives; thus, understanding the cause of high soy viscosities is important. Lack of literature on aqueous soy flour dispersion rheology led to our dynamic rheology studies of these dispersions to understand high viscosity and the effect of various additives...

A wide variety of mathematical models exist which attempt to assess the risk of mold growth in building envelopes. Model predictions often fail to adequately represent observations from field experiments. We examine ways in which one model, the mold resistance design (MRD) model, can be improved to better align with empirical data. A database of laboratory mold growth results was assembled from the literature, which included not only the European spruce and pine on which pioneering models were based, but also materials commonly used in North America, such as oriented strand board (OSB) and...

Lignin is a by-product of biorefineries and pulp and paper manufacturers. Lignin is a renewable source of phenolic precursors for fuels and chemicals. Hydrogenolysis of lignin cleaves the abundant β-O-4 bonds and releases phenolics. However, selective hydrogenolysis of lignin’s β-O-4 bonds is challenging because it requires high-pressure H2. Here we show efficient hydrogenolysis of lignin model compounds and technical lignin by Ru/C catalyst and internal hydrogen. The aliphatic hydroxyl groups (Cα OH) in lignin enabled Ru-catalyzed dehydrogenation of internal hydrogen and the formation of...

Wood-water interactions are central to the utilization of wood in our society since water affects many important characteristics of wood. This topic has been investigated for more than a century, but new knowledge continues to be generated as a result of improved experimental and computational methods. This review summarizes our current understanding of the fundamentals of water in wood and highlights significant knowledge gaps. Thus, the focus is not only on what is currently known but equally important, what is yet unknown. The review covers locations of water in wood; phase changes and...

The United States Capitol building was breached on January 6, 2021. Historically significant materials, many made of wood, were stolen, damaged, or destroyed. Shortly after the breach, the USDA Forest Service, Forest Products Laboratory (FPL) was contacted by the Department of Defense and the Architect of the Capitol and asked to provide technical advice and vintage lumber to aid in restoration efforts. This technical report includes the following: (1) details of FPL efforts to provide vintage lumber specimens to the Architect of the Capitol staff for use in repair of the U.S. Capitol...

In July, month-over-month data continued a negative movement in the majority of data categories. Year-over-year data were better; however, single-family permits decreased again. Again, this portends further moderation in single-family activity in the forthcoming months. July also was the sixth consecutive monthly decrease for existing house sales.

Sea level rise (SLR) is among the climate-change-related problems of greatest concern, threatening the lives and property of coastal residents and generating far-reaching economic and ecological impacts. We project that SLR will lead to an increase in the rate of new housing construction to replace destroyed structures, impact global wood products supply and demand conditions, and cause changes in global forest sector carbon mitigation potential. Findings indicate that 71 million new units will be built by 2050 to accommodate the SLR-affected global population. More than two-thirds of...

Cellulose nanomaterials derived from wood, plants, and other organisms provide mechanical reinforcement to a wide variety of polymers. The reproducibility and uniformity of these bioderived and biodegradable nanomaterials makes them suitable for use in existing petrochemical-derived polymers and resins in which relatively simple and pure molecules are used. The composites benefit from improved mechanical, thermal, rheological, and other properties while imparting biobased content (new carbon), thereby sequestering carbon in a multitude of products. The refractive index match between...