Treesearch

The second glued-laminated structure built in the United States was constructed at the USDA Forest Products Laboratory (FPL) in 1934 to demonstrate the performance of wooden arch buildings. After 75 years of use the structure was decommissioned in 2010. Shortly after construction, researchers structurally evaluated the glued-laminated arch structure for uniform loading on the center arch. This structural system evaluation was added to the existing laboratory work on glued-laminated arches to develop the foundation on which the current glued-laminated arch design criteria is based. After 75...

Homogeneous and transparent CNF films, fabricated from the (2,2,6,6- tetramethylpiperidin-1-yl) oxyl (TEMPO)-modified CNF suspension, were laminated onto wood flakes (WF) based on phenol-formaldehyde (PF) resin and the reinforcement potential of the material has been investigated. The focus was on the influence of CNF film lamination, relative humidity (RH), heat treatment, and anisotropic properties of WF on the CNF-WF laminate tensile properties (elastic modulus, ultimate tensile strength, strain to failure). Results demonstrated that CNFWF laminates had improved mechanical performance...

Nature has often provided inspiration for new smart structures and materials. Recently, we showed a bundle of a few wood cells are moisture-activated torsional actuators that can reversibly twist multiple revolutions per centimeter of length. The bundles produce specific torque higher than that produced by electric motors and possess shape memory twist capabilities. Here we also report that ion diffusion through wood cell walls is a stimuli-responsive phenomenon. Using the high spatial resolution and sensitivity of synchrotron-based x-ray fluorescence microscopy (XFM), metal ions deposited...

In the field of conversion of biomass to ethanol, an important area of research is the enzymatic hydrolysis of cellulose. Once cellulose is converted to glucose, it can be easily fermented to ethanol. As the cellulosic ethanol technology stands now, costly pretreatments and high dosages of cellulases are needed to achieve complete hydrolysis of the cellulose fraction of the biomass.1-3 This is mostly due to the inability of the enzymes to fully access the cellulose fraction given the complex plant cell wall structure. Many different technologies are being developed to modify the biomass to...

The fate of lignin from wheat straw, Miscanthus, and Loblolly pine after pretreatment by a non-toxic and recyclable ionic liquid (IL), [C2mim][OAc], followed by enzymatic hydrolysis was investigated. The lignin partitioned into six process streams, each of which was quantified and analyzed by a combination of a novel solution-state two-dimensional (2D) nuclear magnetic resonance (NMR) method, and size exclusion chromatography (SEC). Pretreatment of biomass samples by [C2mim][OAc] at 120 and 160 °C enhances hydrolysis rates and enzymatic glucan digestions compared to those of untreated...

This paper characterizes the corrosion rate of embedded fasteners as a function of wood moisture content using gravimetric and electrochemical measurements. The results indicated that the corrosion rate increased with moisture content before reaching a plateau. The phases present in the corrosion products, as analyzed using X-ray diffraction, are generally consistent with previous work. Uniform corrosion was observed for all fasteners and all conditions except steel fasteners embedded in water-saturated wood. Data of dependence of corrosion rate on moisture content, presented herein, are...

Wood is a durable engineering material when used in an appropriate manner, but it is susceptible to biological decay when a log, sawn product, or final product is not stored, handled, or designed properly. Even before the biological decay of wood becomes visually apparent, the decay can cause the wood to become structurally unsound. The progression of decay to that critical state depends heavily on temperature and moisture conditions. As a preventative measure, wood preservatives are chemical treatments applied to wood to protect less-durable wood species from decay. To ensure that these...

This study applied dilute acid (DA) and sulfite pretreatment to overcome the recalcitrance of lignocelluloses (SPORL) to deconstruct earlywood and latewood cell walls of Douglas fir for fermentable sugars production through subsequent enzymatic hydrolysis. DA pretreatment removed almost all the hemicelluloses, while SPORL at initial pH=4.5 (SP-B) removed significant amount of lignin between 20 and 25 %. But both are not sufficient for effective enzymatic saccharification. SPORL at low initial pH=2 (SP-AB) combines the advantage of both DA and SPORL-B to achieve approximately 90 % hemicellul...

The Forest Products Laboratory (FPL) has provided equilibrium moisture content (EMC) values of wood for given temperature and relative humidity (RH) conditions in various forms over the course of its history, primarily for practical purposes related to drying lumber and controlling moisture content. The FPL EMC data have been widely cited and reprinted, not only in literature of a practical nature such as the Wood Handbook, but also in textbooks and journal articles as a basis for scientific discourse on the thermodynamics of water vapor sorption in wood and evaluation of physical models....

Wood specific gravity (SG) is widely employed by ecologists as a key variable in estimates of biomass. When it is important to have nondestructive methods for sampling wood for SG measurements, cores are extracted with an increment borer. While boring is a relatively difficult task even at breast height sampling, it is impossible at ground level and arduous at heights above a couple of meters. Therefore, if a nondestructive estimate of the biomass of a whole stem is required, the variation of SG with height must be known. Here we look at the SG variation with height of five tropical trees,...