Treesearch

The fire resistance ratings of wood members and assemblies, as of other materials, have traditionally been obtained by testing the assembly in a furnace in accordance with ASTM International (ASTM) Standard E119, International Organization for Standardization (ISO) Standard 834, and similar standards. These ratings are published in listings, such as Underwriters Laboratories Fire Resistance Directory, Gypsum Association's Fire Resistance Design Manual, American Wood Council's Design for Code Acceptance publications, and those in building codes. The ratings listed are limited to the actual...

Chemical additions to wood often change its bulk properties, which can be determined using conventional macroscopic mechanical tests. However, the controlling interactions between chemicals and wood take place at and below the scale of individual cells and cell walls. To better understand the effects of chemical additions to wood, we have adapted and extended two experimental methods for wood science research. The first method entails two-dimensional solution-state nuclear magnetic resonance spectroscopy of wood cell wall polymers after ball milling but without the usual chemical fractionat...

Laboratory-scale experiments were conducted in which preservative metals (As, Cr, & Cu) were thermochemically extracted from CCA-treated spruce (Picea engelmannii) using oxalic acid and sodium hydroxide. The effects of extraction time, temperature, and pH were examined and laboratory scale optimization was achieved. Two series of experiments were carried out. In the first series, the extractions were done at temperatures ranging from 20 to 80[degrees]C and with the pH of 1% oxalic acid solutions adjusted between 1.4 and 3.6 with sodium hydroxide. The second series of experiments were...

This paper compares average ratings of test stakes after 3, 4, 5, and 7 years exposure to their subsequent ratings after 11 years. Average ratings from over 200 treatment groups exposed in plots in southern Mississippi were compared to average ratings of a reference preservative. The analysis revealed that even perfect ratings after three years were not a reliable indicator of good performance after 11 years. Only 53% of the treatment groups with an average rating of 10.0 after 3 years had ratings at least as great as the reference preservative after 11 years. This percentage increased to...

The most challenging part of developing acceptable adhesives for wood bonding often is to create a bond that will withstand exposure to wet conditions or wet/dry cycles. Products that pass these tests have been developed empirically, but the aspects that make it difficult for adhesives to pass these tests and systematically ways to develop more durable adhesive bonds have not been researched. The first aspect is that the swelling strain of wood can impart sufficient force to contribute to the bond fracture if interfacial strain between the adhesive and wood is not dissipated through the...

Subterranean termite infestations occur in every state in the contiguous United States and are responsible for damage to wooden structures in excess of two billion dollars (U.S.) annually. Essential oils have historically been used to repel insects. They have relatively low toxicity and some of them are exempt from regulation by the Federal Insecticide Fungicide and Rodenticide Act (FIFRA). Development of environmentally friendly wood protection systems may benefit from supplemental essential oils. Eight essential oils were evaluated for their ability to protect wood from attack by...

Depletion of the biocide(s) used to treat wood has a major influence on service life and environmental concerns. However, little is known about the extent of depletion from the specific leaching method employed. Wood treated with two types of copper-based preservatives were leached using three different methods: field stakes (American Wood Protection Association (AWPA) method E7), laboratory soil exposure (AWPA method E20), or laboratory water immersion (AWPA method E11). Average losses tended to be greater from the field stakes than the small method E20 laboratory stakes, but this trend...

A method based on FT-Raman spectroscopy is proposed for determining in situ concentrations of ethylenic residues in softwood lignin. Raman contributions at 1133 and 1654 cm-1, representing coniferaldehyde and coniferyl alcohol structures, respectively, were used in quantifying these units in spruce wood with subsequent conversion to concentrations in lignin. For coniferaldehyde units, the intensity of the 1133 cm-1 peak was measured in the difference spectrum obtained by subtracting the bleached-wood spectrum from that of the unbleached. In the case of coniferyl alcohol residues, the...

Demand for the development of environmentally benign wood preservatives has increased significantly. To reduce the evaluation time of prospective candidates, reliable accelerated decay methodologies are necessary for laboratory screening of potential preservatives. Ongoing research at Mississippi State University has focused upon utilizing custom built equipment to measure stiffness losses in wood wafers after 4 weeks of fungal exposure as opposed to mass losses in blocks after 12 weeks. Stiffness loss as a measure to quantify the extent of biodeterioration may allow detection of incipient...

Wood block specimens pre-steamed at 120-220 °C for 5-20 min were compressed in the radial direction. The recovery of set decreased with increasing pre-steaming temperature and time. The reduction of set recovery correlated with the amount of weight loss in steaming irrespective of pre-steaming temperature and time. The weight loss for the highest level of fixation of compressive deformation was about 7.5% that was obtained by pre-steaming at 210-220 °C for 10 min. Moreover, the set recovery of the pre-steamed specimen decreased as pressing temperature and time increased. The compressibility...