Treesearch

Southern pine solid wood (SPS) and fiber (SPF) were chemically modified to various weight percent gains (WPG) using either acetic anhydride (AA, 4%-19% WPG), butylene oxide (BO, 4%-23% WPG), or propylene oxide (PO, 6%-30% WPG). After modification, part ofthe specimens were extracted with a toluene:ethanol (2:1) solution for 2 hours or water leached for 2 weeks. The equilibrium moisture content (EMC) at 30%, 65% and 90% relative humidity (RH) and 27 °C was determined on all specimens. Laboratory soil block decay testing using the brown-rot fungus Gloeophyllum trabeum was performed and...

Moisture content has an effect on the biological decay of wood. The literature states that serious decay occurs when the moisture content of wood is above the fiber saturation point (FSP), which is the measurement of the moisture content of wood when the cell walls are saturated and the cell cavities free from water (average 30%). We can chemically modify wood hydroxyls by various treatments (i.e., acetylation, isocyanates, and epoxides) which result in the lowering of the FSP. If we modify the availability of water in the cell wall, we can reduce or eliminate biological degradation. So is...

In a series of papers Verrill, Green, and Herian have developed theory and a computer program to aid in the design and analysis of predictor sort experiments. In this paper we provide the mathematical justification for the power calculations that the predictor sort program implements.

The use of soluble salts of polyoxometalates (d0-early-transition metal oxygen-anion clusters or POMs) as selective oxidation or electron-transfer catalysts, as probes in physical-organic and biological chemistry, and in the study of electron-and energy-transfer phenomena constitutes a substantial and rapidly growing literature. While rarely addressed, however, POM solutions contain equilibrium distributions of free anions and ion-paired structures of variable stoichiometry. Thus, although studies of crystalline POM salts used in heterogeneous catalysis clearly indicate that cation-anionint...

Recently found experimental evidence has provided strong support for an alternative photoyellowing mechanism that suggests that pulp- photoyellowing occurs due to direct photooxidation of hydroquinones (present in mechanical pulps) top-quinones. Because hydroquinones were found to be present in pulps, it may be possible to quantify them. Quantification of mechanical-pulp hydroquinones is important because it would provide information on a pulp's potential for photoyellowing. One of the ways to accomplish this is to use the method that successfully detected hydroquinones, namely the method...

Environmental pressures to replace chromium and arsenic in fixed waterborne preservatives have been increasing. Potential inhibitors of brown-, white- and soft-rot fungi need to be evaluated as alternative preservatives by screening and testing in, in vitro model systems. This paper reports the inhibition of cellulose depolymerization and weight loss of selected decay fungi by 11 chemical compounds. The ability to depolymerize carbohydrate polymers is analogous to strength loss of wood which can occur independently of utilization (weight loss). Cotton cellulose was pretreated with 1%...

The calcium precipitating agent NHA has been shown to protect southern yellow pine (SYP) from wood decay and termite damage comparable to CCA in field tests (Gulfport, MS) for two years (Crawford and Green, 1999). In a collaborative study, SYP wood blocks were vacuum treated with three concentrations of aqueous NHA and exposed in a no-choice test to Eastern subterranean termites (FPL, USA) and Formosan subterranean termites (WRI, Japan) to determine protection against termite damage. Individual blocks (leached and unleached) were exposed to R. flavipes (AWPA) or C. formosanus (JWPA) for...

The technology currently exists to manufacture natural fiber-thermoplastic composites from recycled materials. Development of commodity building products from these composites would open huge markets for waste-based materials in the United States. To date, the construction industry has only accepted wood-thermoplastic composite lumber and only for limited applications. In a little more than a decade, the use of composite decking has grown to about 4% of the exterior decking market. Even larger markets within the building industry could be developed, such as the roofing market. However, a...

A large sample of timber was collected from a 548,000-ft.2 (50,900-m2) World War II era industrial military building containing approximately 1, 875,000 board feet (4,400 m3) of lumber and timber. Sixty 12-foot- (3.6-m-) long, nominal 8- by 8-inches (190-by 190-mm) Douglas-fir columns were tested at the USDA Forest Service, Forest Products Laboratory, and the results were compared with the National Design Specification allowable design capacity. The effects of seasoning checks and splits on residual column strength are presented. Results indicate that about one-third of the columns were...

The Midwest Roadside Safety Facility, in cooperation with the Forest Products Laboratory, which is part of the U.S. Department of Agricultureas Forest Service, and FHWA, designed two bridge railing and approach guardrail transition systems for use on bridges with transverse glue-laminated timber decks. The bridge raging and transition systems were developed and crash tested for use on higher-service-level roadways and evaluated according to the Test Level 4 safety performance criteria presented in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway...