Treesearch

The RPA Timber Assessment projects, over the next 50 years, the likelihood of increasing relative use of imported forest products versus U.S. roundwood harvest to meet U.S. consumption needs, although our projected consumption needs are now estimated to be lower than we projected in 1993. The projected higher imports relative to U.S. roundwood harvest is due in part to slower projected increase in available hardwood inventory and harvest in the South. Softwood harvest is projected to increase notably with increasing area and management intensity for plantations in the South, and we project...

Considerable interest has been generated in the use of lignocellulosic fibers and wastes (both agricultural and wood based) as fillers and reinforcements in thermoplastics. In general, present technologies limit fiber loading in thermoplastics to about 60 percent by weight of fiber. To produce high fiber content composites for commercial use while maintaining adequate mechanical properties requires innovative processing techniques. A new technique has been developed that allows very high fiber loading. We have processed composites up to about 95 percent by weight of fiber in polypropylene...

Aspen fiber-polypropylene composites were prepared with various levels of fiber (0,30%, 40%, 50%, and 60%), polypropylene (PP) (100%, 98%, 70%, 68%, 60%, 58%, 50%, 48%, 40%, and 38%), and the compatibilizer maleated polypropylene (MAPP) (0 and 2%). Specimens were either subjected to 10 cycles of 1 week room temperature water soaking-oven drying or 2-hr. boiling wateroven drying. Thickness swelling and weight loss were calculated. Specimens were then exposed to the brown-rot fungus G. trabeum or the white-rot fungus C. versicolor for 12 weeks to determine the effect of repeated water...

It is often proposed that brown rot basidiomycetes use extracellular reactive oxygen species (ROS) to accomplish the initial depolymerization of cellulose in wood, but little evidence has been presented to show that the fungi produce these oxidants in physiologically relevant quantities. We used [14C]phenethyl polyacrylate as a radical trap to estimate extracellular ROS production by two brown rot fungi, Gloeophyllum trabeum and Postia placenta, that were degrading cellulose. Both fungi oxidized aromatic rings on the trap to give monohydroxylated and more polar products in significant...

Research at the Forest Products Laboratory (FPL) related to durability and disaster mitigation includes damage by decay fungi and termites and contamination by mold fungi. All these household pests are attracted to excess moisture, which can result from inadequate surface drying of condensation, leaks in pipes and foundations, poor ventila-tion, or flooding. Homeowners are increasingly concerned about moisture management and indoor air quality (IAQ). However, chronic moisture problems in a home can lead to more than poor IAQ—persistent high moisture can lead to a cascading biological...

Prototype designs for wood highway sound barriers meeting the multiple criteria of structural integrity, acoustic effectiveness, durability, and potential for public acceptance have been developed. Existing installations of wood sound barriers were reviewed and measurements conducted in the field to estimate acoustic insertion losses. A complete matrix of design options for wood barriers was developed into a set of 35-mm slides along with several concrete designs, and presented in a controlled test to a group of human subjects for evaluation. Results of this testing showed that the wood...

Evaluation of existing timber structures requires procedures to evaluate in situ structural members and components. This report evaluates the transverse vibration response of laboratory-built floor systems with new and salvaged joists. The objectives were to 1) compare floor system response to individual member response; 2) examine response sensitivity to location of the forcing function; and 3) compare the response of a floor constructed with new joists to that of a floor constructed with a combination of new and salvaged joists. Several floor systems were constructed from new and...

Water-repellency of preservative formulations used in the millwork industry has long been evaluated by measurement of the dimensional changes in wood treated and then submerged in water according to guidelines published by the millwork industry. Perceptions that this swellometer test was highly variable led to a round-robin test of one solvent-borne and one waterborne commercial formulation by five independent laboratories in order to assess the variation in results among labs. These data were then used to address the sample size needed to achieve a 90 percent confidence level in the mean...

This research develops a model using finite element to study the response of a panel made of a typical commercial corrugated fireboard due to an induced moisture function at one side of the fiberboard. The model predicts how the moisture diffusion will permeate through the fiberboard's layers (medium and liners) providing information on moisture content at any given point throughout the structure. The short column is loaded by edgewise compression, all panel edges are simply supported. This is one type of boundary conditions; other boundary conditions can be investigated. The model...

High temperature steam treatment of wood fiber in a closed press during fiberboard pressing and then cooling the fiberboard while still under pressure to below the glass transition temperature of lignin, greatly increased the dimensional stability and decreased the hemicellulose content of the fiberboards produced. For example, after pressing aspen fiber four minutes at 200 C under steam pressure, the resulting fiberboards show less than 10 percent thickness swelling after two-hour water soak as compared to over 40 percent for non-steamed fiberboards. The addition of ferric chloride to the...