Treesearch

Thermal condensation of glucose-diammonium phosphate in wood at 160 and 190[degrees]C will protect wood against fire and decay in one treatment using an aqueous system. For fire protection, treatments at 160 or 190[degrees]C led to low flammability as evidenced by fire-tube tests. For nonleached wood, weight losses were 1.9, 2.0, and 2.0% with chemical retentions of 56.7, 44.7, and 64.7%, respectively, for 2-, 4-, and 6-h heating; and for leached wood, weight losses of 5.1, 3.8, and 1.5% with chemical retentions of 24.5, 24.1, and 45.6%, respectively, for 2-, 4-, and 6-h heating compared...

This study investigated the potential of using acoustic tomography for detecting internal decay in high-value hardwood trees in the forest. Twelve black cherry (Prunus serotina) trees that had a wide range of physical characteristics were tested in a stand of second-growth hardwoods in Kane, PA, using a PiCUS Sonic Tomograph tool. The trees were felled after the field test and a disc from each sampling height was cut and subjected to laboratory evaluations. It was found that acoustic tomography underestimates heartwood decay when it is the major structural defect in the trees. However,...

Large numbers of black oak (Quercus velutina Lam.) and scarlet oak (Quercus coccinea Muenchh.) trees are declining and dying in the Missouri Ozark forest as a result of oak decline. Red oak borer-infested trees produce low-grade logs that become extremely difficult to merchandize as the level of insect attack increases. The objective of this study was to investigate the use of a resonance-based acoustic technique to evaluate the wood quality of infested red oak logs before processing as measured by grade, type and location of defects, and mechanical properties of the resulting boards....

Internal steam pressure produced during the hot-pressing cycle in particleboard production is critical to the newly developed bond strength that will determine the overall performance of particleboard. The difference between the accumulation of internal steam pressure for small panels made in the laboratory and that of large commercial-sized panels makes it difficult to transfer knowledge gained from the laboratory to the commercial plant. The objective of this research project is 2-fold: first, to investigate the effect of panel size on the initial development and subsequent dissipation...

The wood decay basidiomycete Phanerochaete chrysosporium was grown under standard ligninolytic or cellulolytic conditions and subjected to whole-genome expression microarray analysis and liquid chromatography-tandem mass spectrometry of extracellular proteins. A total of 545 genes were flagged on the basis of significant changes in transcript accumulation and/or peptide sequences of the secreted proteins. Under nitrogen or carbon limitation, lignin and manganese peroxidase expression increased relative to nutrient replete medium. Various extracellular oxidases were also secreted in these...

Whenever a nanoindent is placed near an edge, such as the free edge of the specimen or heterophase interface intersecting the surface, the elastic discontinuity associated with the edge produces artifacts in the load-depth data. Unless properly handled in the data analysis, the artifacts can produce spurious results that obscure any real trends in properties as functions of position. Previously, we showed that the artifacts can be understood in terms of a structural compliance, Cs, which is independent of the size of the indent. In the present work, the utility of the SYS (Stone, Yoder,...

The development of nanoindentation test systems with high data collection speeds has made possible a novel type of indentation creep test: broadband nanoindentation creep (BNC). Using the high density of data points generated and analysis techniques that can model the instantaneous projected indent area at all times during a constant-load indentation experiment, BNC can reveal materials properties across a range of strain rates spanning up to five decades (10-4--10 s-1). BNC experiments aimed at measuring activation parameters for plasticity were conducted on three systems: two Zr-based...

A series of commercially manufactured medium density fiberboard (MDF) panels were exposed to a post-manufacture heat-treatment at various temperatures and durations using a hot press and just enough pressure to ensure firm contact between the panel and the press platens. Post-manufacture heat-treatment improved surface roughness of the exterior MDF panels. Panels treated at 225[degrees]C for 30 min had the smoothest surface while the roughest surface was found for the control panels. Wettability and the adhesive bonding strength between veneer sheet and panel surface were decreased as...

Saltcedar (Tamarix ramosissima) was investigated for use as a filler in wood–plastic composites (WPCs). The mineral content, water-soluble extractive content, and thermal stability of saltcedar flour were compared with those of a commercial pine wood flour. The wood flours were compounded with plastic, and the viscosities of the composite melts containing the two species were compared. Injection-molded composites produced from the compounded material were evaluated for mechanical performance and weatherability. Saltcedar flour had more minerals and water-soluble extractives than pine...

Wood-plastic composites (WPCs) have been gaining market share in residential construction applications such as lumber for decking, roof tiles, and siding. The durability of these materials in exterior environments is just beginning to be understood. Current research suggests that controlling moisture absorption by the composite is key to improving durability. Methods to improve moisture resistance of WPCs have met with limited success. Co-extrusion involves the simultaneous extrusion of two dissimilar materials as a single profile. A previous study demonstrated that co-extrusion of a base...