Treesearch

This research evaluated the potential of wood fiber to chemically decompose during hot-pressing. We evaluated changes in carbohydrate composition and structure as a function of multiple press temperatures (180°, 200°, and 220°C) and an array of hot-pressing durations from 180 to 2500 s. Results show how this thermal degradation in chemical composition directly results in changes in moisture sorption characteristics, physical and mechanical properties, and aboveground durability. For most mechanical properties, it appears that very little degrade occurs until mat temperatures exceed 150°C....

To be a successful marina owner and operator, it’s important to understand all the facets of one’s facility, including the intricacies of one part of the marina that most boaters take for granted: the docks. When it comes to dock construction, marinas have a wide-range of materials to choose from, with one of the most commonly used materials being preservative-treated wood. This article examines the role the government plays and the role marinas and contractors can play when using wood for construction purposes.

Composites based on high density polyethylene (HDPE), pine flour, and organic clay were made by melt compounding and then injection molding. The influence of clay on crystallization behavior, mechanical properties, water absorption, and thermal stability of HDPE/pine composites was investigated. The HDPE/pine composites containing exfoliated clay were made by a two-step melt compounding procedure with the aid of a maleated polyethylene (MAPE). The use of 2% clay decreased the crystallization temperature (Tc), crystallization rate, and the crystallinity level of the HDPE/pine composites,...

Hybrids based on recycled high density polyethylene (RHDPE) and organic clay were made by melt compounding. The influence of blending method, compatibilizers, and clay content on clay intercalation and exfoliation, RHDPE crystallization behavior, and the mechanical properties of RHDPE/clay hybrids were investigated. Both maleated polyethylene (MAPE) and titanate could improve the compatibilization of RHDPE and clay. RHDPE/clay hybrids containing completely exfoliated clay were obtained using a two-step blending method. Without compatibilizers, the clay could not be exfoliated, and it...

The limited penetration of wood by light explains why the weathering of wood exposed outdoors is a surface phenomenon. Wood is rapidly degraded by short-wave-length UV radiation, but the penetration of light into wood is positively correlated with its wavelength. Hence, subsurface degradation is likely to be caused by longer-wavelength light that still has sufficient energy to degrade wood. In this paper we test this hypothesis and determine the wavelengths of visible light that extend photo-degradation into wood beyond the zone affected by UV radiation. Sugi (Cryptomeria japonica)...

Temperature histories for various types of roof shingles, wood roof sheathing, rafters, and nonventilated attics were monitored in outdoor attic structures using simulated North American light-framed construction. In this paper, 3-year thermal load histories for wood-based composite roof sheathing, wood rafters, and attics under western redcedar (WRC) shingles, wood-thermoplastic composite (WTPC) shingles, and black and white fiberglass shingles are reported and analyzed. The maximum hourly-average temperatures experienced were 70.7 °C and 61.8 °C for black and white fiberglass shingles,...

Founded in 1910 by the U.S. Forest Service to serve as a centralized, national wood research laboratory, the USDA Forest Products Laboratory (FPL) has a long history of providing technical services to other government agencies, including those within the Defense (DoD). A recent search of FPL’s library and correspondence files revealed that approximately 10,000 articles, reports, manuals, other technical publications, and communications have been generated and provided to the DoD since 1910. FPL has provided support on a broad array of technical questions—from designing lightweight packaging...

In this study, silane cross-linked wood–polyethylene composite profiles were manufactured by reactive extrusion. These composites were evaluated regarding their durability and mechanical properties in comparison with two non-cross-linked wood– polyethylene composites. An addition of only 2% w/w of silane solution during manufacturing was enough to achieve almost 60% degree of cross-linking after curing. The cross-linked composites showed flexural toughness superior to the non-cross-linked composites. The cross-linked composites also absorbed less moisture during a boiling test in water and...

A universal, rapid DNA assembly method for efficient multigene plasmid construction is important for biological research and for optimizing gene expression in industrial microbes. Three different approaches to achieve this goal were evaluated. These included creating long complementary extensions using a uracil-DNA glycosylase technique, overlap extension polymerase chain reaction, and a SfiI-based ligation method. SfiI ligation was the only successful approach for assembling large DNA fragments that contained repeated homologous regions. In addition, the SfiI method has been improved over...

Xylose was fermented using Pichia stipitis CBS 6054 at different initial cell concentrations. A high initial cell concentration increased the rate of xylose utilization, ethanol formation, and the ethanol yield. The highest ethanol concentration of 41.0 g/L and a yield of 0.38 g/g was obtained using an initial cell concentration of 6.5 g/L. Even though more xylitol was produced when the initial cell concentrations were high, cell density had no effect on the final ethanol yield. A two- parameter mathematical model was used to predict the cell population dynamics at the different initial...