Treesearch

On October 9, 2023, the main mast of the historic schooner Grace Bailey unexpectedly snapped at about two-thirds of its height and fell onto the deck, killing one passenger and injuring three others. The United States Coast Guard promptly initiated a formal investigation into the cause of the mast’s sudden failure. At the request of the Coast Guard, the U.S. Department of Agriculture, Forest Service, Forest Products Laboratory (FPL) conducted an on-site evaluation of the broken mast on December 19, 2023. The inspection used nondestructive testing methods and included visual analysis,...

While buildings have been constructed of wood for centuries, mass timber has revolutionized wood as a building material by enabling construction of high-rise wood buildings, thereby rivaling concrete and steel. Using cross-laminated timber—a form of mass timber made by stacking and adhering dried lumber in alternating directions into solid panels—can increase construction speeds while sequestering carbon, reducing emissions, and providing a market for sustainable forest products.As the number and complexity of structures made with cross-laminated timber continue to increase, critical fire...

A ductile lateral force resisting system (LFRS) for mass timber frames is proposed utilizing Mass Timber Buckling- Restrained Braces (MT-BRBs), with mass timber as the primary casing material. Compressive tests were conducted on Mass Plywood Panels (MPP) with and without horizontal self-tapping screws inserted perpendicular to laminations to assess differences in stiffness, peak load, and maximum displacement. Screws perpendicular to lamination enhanced performance, increasing the peak load by nearly four times and peak displacement by more than three times. Withdrawal tests were also...

An historic 1934 building on the campus of the U.S. Department of Agriculture, Forest Service, Forest Products Laboratory was deconstructed in 2010. The glued-laminated (glulam) beams from the building were preserved, creating a unique opportunity to test the casein adhesive bonding in the beams that had been in service for more than 75 years. The goal of the testing reported in this study was to extend the understanding of protein adhesives in wood products. In this study, we tested wet and dry strength of the bonds using compressive block shear tests. We also tested for delamination and...

The evolution of next-generation flexible, stretchable, and conformal microrobotics hinges significantly on advances in fabrication methods. There is a need to enhance the scalability of actuator feature dimensions and to increase the design versatility. This study demonstrates the additive manufacturing of soft multi-stimulus thermomechanical actuators based on a composite of transition metal carbide (TMC, MXene) and cellulose nanofiber (CNF) nanomaterials using aerosol jet printing (AJP) for scalable/customizable actuation. Aqueous MXene-CNF films with tunable electrothermal and photother...

Wood that is resistant to fungal degradation is highly desirable, and chemical acetylation is one way to inhibit wood decay. The open question is whether acetylation inhibits decay strictly by reducing moisture content within the cell wall or if specific interactions with the acetyl group hinder motion within the cell wall and further inhibit decay. We investigate these hypotheses through molecular simulation, acetylating exposed hemicellulose and lignin hydroxyl groups in a secondary plant cell wall model. By comparing diffusion within the model, we find that acetyl group interactions...

The particle number concentration (PNC) in a suspension is a key measurand in nanotechnology. A common approach for deriving PNC is to divide the total mass concentration by the per-particle mass, calculated as density times volume. The volume is most frequently derived from the arithmetic mean diameter (AMD) of the size distribution. The harmonic mean volume (HMV) has also been used. Given a known size distribution, we show that the correct PNC is obtained by using the arithmetic mean volume (AMV). The AMD-based volume results in an overestimate in PNC that increases superlinearly with...

Plantation forests in the southeastern United States are dominated by loblolly pine (Pinus taeda L.) whose wood is used to supply the lumber, composite, pellet, and pulp and paper industries; processing of this timber affords bark as a major byproduct. To date, information is limited regarding the variation of loblolly pine bark properties with relative tree height and how these trends vary with physiographic region. For this study, 139 stands across the natural range of loblolly pine were destructively sampled with three trees felled from each stand. Bark properties, specific gravity...

This study presents a cellulose nanocrystals (CNCs)/polydimethylsiloxane (PDMS) composite membrane for enhanced water vapor separation at elevated temperatures. CNCs/PDMS membranes were fabricated via a casting method and characterized for their permeability, selectivity, and thermal stability. Water vapor permeability was measured using a Payne diffusion cell coupled with a Dynamic Vapor Sorption instrument, while nitrogen gas permeability was determined with a gas permeation cell. The results indicate that incorporating 2% CNCs increased water vapor permeability by 24.8%, 30.9%, and...

Cellulose nanocrystals (CNCs) are purported as potential nanoreinforcements in polymer composites; however, the hydrophilic surface nature of CNCs limits their usage in composites if the polymers are hydrophobic, which results in poor compatibility. In this research, renewable biobased CNCs were modified using silylation, which is based on introducing a siloxane group to increase the compatibility between CNCs and the polydimethylsiloxane (PDMS) polymer. A silylated CNC/PDMS composite membrane was manufactured, which has applications in air dehydration. For this purpose, spray-dried CNC...