Treesearch

Wood-plastic composites (WPCs) have slower moisture sorption than solid wood, but over time moisture can impact the strength, stiffness, and decay of the composite. These changes will become increasingly important if WPCs are used in more challenging environments such as in ground-contact applications. There are several options for mitigating the moisture sorption of WPCs. A coupling agent can be added to potentially improve the wetting and dispersion of the wood flour and improve its adhesion with the plastic matrix. In previous investigations, the use of a coupling agent has been shown...

Imagine if you could measure all the genes being expressed at any one time in an organism and you knew what all the genes did in a cell. The power of this knowledge would allow you to determine how organisms regulate gene activity to survive. This is the essence of how “omics” science accelerates biological understanding. From a wood protections standpoint, understanding which genes regulate copper tolerance effectively identifies metabolic chokepoints that would have the highest likelihood of interfering with copper tolerance. Thus, the search for copper co-biocides is no longer random,...

The termite hindgut contains a bacterial community that symbiotically aids in digestion of cellulosic materials. For this paper, a species survey of bacterial hindgut symbionts in termites collected from Saucier, Mississippi was examined. Two methods were tested for optimal genetic material isolation. Genomic DNA was isolated from the hindgut luminal contents of five termites and 16S ribosomal RNA (rRNA) gene fragments were amplified with 16S rRNA amplicon primers. The fragments were cloned into E. coli cells and plasmid DNA was isolated from subsequent clones for sequencing. The results...

The state of Wisconsin’s Department of Natural Resources is responsible for operating one of the largest state park systems in the United States. Peninsula State Park, one of the state’s most visited parks, attracts more than one million visitors a year. This park contained one of the most iconic structures in the Wisconsin State Park system, a tall, wooden observation tower that was constructed in 1932. Because of concerns about the structural integrity of several of the large timbers in the tower, it was closed in the spring of 2015 and dismantled in fall 2016 at the request of the...

Recently, the dynamic vapor sorption (DVS) technique has been used to measure sorption isotherms and develop moisture-mechanics models for wood and cellulosic materials. This method typically involves measuring the time-dependent mass response of a sample following step changes in relative humidity (RH), fitting a kinetic model to the data, and extrapolating the asymptotic mass. A series of steps covering the full RH range is used to generate the sorption isotherm. The majority of prior DVS data were taken with hold times of either 60 min or until the change in moisture content was <0.002%...

Resorcinol-formaldehyde adhesives can reinforce stress fractures that appear from wood surface preparation. Researchers have found that applying the resorcinol-formaldehyde prepolymer, hydroxymethylated resorcinol is thought to plasticize lignin components and stabilize stress fractures through reactions with lignin subunits and hemicelluloses in wood. In this study, a dilute solution of hydroxymethylated resorcinol (HMR) is cured in the presence of a crude milled-wood lignin (cMWL) from Acer saccharum and subsequently dissolved in dimethylsulfoxide-d6 to delineate reactivity with lignin...

Lower termites (Isoptera: Rhinotermitidae) are considered severe pests of wood in service, crops and plantation forests. Termites mechanically remove and digest lignocellulosic material as a food source. The ability to digest lignocellulose not only depends on their digestive physiology, but also on the symbiotic relationship between termites and their intestinal microbiota. The current study was designed to test the possible effects of four heartwood extractives (Tectona grandis, Dalbergia sissoo, Cedrus deodara and Pinus roxburghii) on the mortality, feeding rate and protozoan population...

Efforts are underway in the United States to improve the conformance of commercially-treated wood with the applicable retention standards. As part of an effort to devise a practical method for on-site assessment of within-charge retention variation, we investigated whether small-volume x-ray fluorescence (XRF) sample cups could be used with treated wood. A range of cup sizes, preservative types, retention levels and other variables were considered. In general, small volume cups appear to be suitable for use with common industrial XRF machinery. This finding is being applied to a proposed...

This study was aimed to identify the best approach for incorporating cellulose nanocrystals (CNCs) into a poly(lactic acid) (PLA) matrix by examining two different CNC addition approaches. The first approach consisted of melt blending PLA and CNCs in a three-piece internal mixer whereas the second method involved the direct dry mixing of PLA and CNCs. The prepared compounded materials were then blown into films and compared in terms of fiber dispersion, optical, thermal and barrier properties. The experimental results indicated that the extent of fiber dispersion was not influenced by the...

Utilizing lignin-containing cellulose nanocrystals (HLCNCs) as reinforcing agents to poly(lactic acid) (PLA) for nanocomposites was studied for the first time. The PLA/HLCNCs nanocomposites were prepared by extrusion and injecting molding. The freeze-dried HLCNCs showed micron scale agglomerates. As indicated by the water contact angle measurements, the HLCNCs were more hydrophobic than dealkaline lignin and traditional, lignin-free CNCs derived from high cellulose content wood pulp. Thermogravimetric analysis (TGA) showed that the HLCNCs started to degrade at about 300°C. The thermal...