Treesearch

Advances in wood protection based on nanotechnology are being developed to improve resistance of wood products to biodeterioration, reduce environmental impacts from chemical leaching and resist UV degradation of in-service wood. A number of different approaches have been explored. First, the nanometals zinc oxide and copper oxide were evaluated as preservative treatments for wood. Both nanoZnO and nanoCuO were leach resistant. NanoZnO also inhibited decay fungi, acted as a termite toxicant, and provided photostability of wood against UV degradation. Second, self-assembling nanopolymer...

From 2005–10, the USDA Forest Service’s Woody Biomass Utilization Grant program provided grants for equipment acquisition and technical assistance to rural businesses and other entities. These grants were intended to encourage enterprise development, address market barriers to biomass utilization (ranging from small-diameter sawtimber to chips and logging residues), and decrease forest restoration costs by adding value to biomass products. At the request of the USDA Forest Service – State and Private Forestry’s Forest Products Technology Marketing Unit at the Forest Products Laboratory, we...

The reinforcement potential of cellulose nanocrystal (CNC) additions on an idealized 2-dirmensional (2-D) fiber network structure consisting of micron sized fiber elements was investigated. The reinforcement mechanism considered in this study was through the stiffening of the micron sized fiber elements via a CNC-epoxy coating. A hierarchical analytical modeling approach was used to estimate the elastic properties spanning three different structural features; i) micromechanics for CNC-epoxy properties, ii) laminate theory for fiber elements coated with CNC-epoxy, and iii) a 2-D network...

The structure of lignin after dilute phosphoric acid plus steam explosion pretreatment process of sugarcane bagasse in a pilot scale and the effect of the lignin extracted by ethanol on subsequent cellulose hydrolysis were investigated. The lignin structural changes caused by pretreatment were identified using advanced nondestructive techniques such as gel permeation chromatography (GPC), quantitative 13C, and 2-D nuclear magnetic resonance (NMR). The structural analysis revealed that ethanol extractable lignin preserved basic lignin structure, but had relatively lower amount of β-O-4...

Rapid quantitative laboratory test methods are needed to screen potential antifungal agents. Existing laboratory test methods are relatively time consuming, may require specialized test equipment and rely on subjective visual ratings. A quantitative, colorimetric micro-assay has been developed that uses XTT tetrazolium salt to metabolically assess mold spore germination. Using isothiazolinone as a model mold inhibitor, the minimum inhibitory concentration (MIC) for the XTT assay was compared with the 4 week ASTM plate method (D4445) to test fungicides for controlling mold and the 8 week...

Protein adhesives allowed the development of bonded wood products such as plywood and glulam in the early 20th century. Petrochemical-based adhesives replaced proteins in most wood bonding applications because of lower cost, improved production efficiencies, and enhanced durability. However, several technological and environmental factors have led to a resurgence of proteins, especially soy flour, as an important adhesive for interior nonstructural wood products. This paper discusses important aspects of protein structure and recent successful advances in higher performance soy flour...

The prime objective of this investigation was to compare mass loss from termite attack on NHA treated and untreated pine blocks simultaneously in a two-block choice test using Reticulitermes flavipes (Kollar). Southern pine blocks were vacuum treated with aqueous solutions of NHA ranging from 250-10,000 ppm and exposed to one gram of R. flavipes workers in the dual block choice test which included one treated and one untreated block per the modified AWPA laboratory test (E1-09). At the end of four weeks, all test blocks were removed, weighed and the mass losses statistically modeled using...

Covered bridges can be vulnerable to damage from fungal decay and insect attack. This paper describes procedures for selecting and applying in-place treatments to prevent or arrest biodegradation, and summarizes recent research evaluating some of these treatments. Wood moisture is the key to decay and termite attack, and the first line of defense against biodeterioration is to minimize moisture intrusion through prompt maintenance and repair. Biodeterioration will tend to be more prevalent wherever members contact abutments, are near the ends of bridges subject to wetting from splashing,...

Ordinal rating systems are commonly employed to evaluate biodeterioration of wood exposed outdoors over long periods of time. The purpose of these ratings is to compare the durability of test systems to nondurable wood products or known durable wood products. There are many reasons why these systems have evolved as the chosen method of evaluation, including having an overall evaluation that incorporates several characteristics thought to correlate with some “failure,” balancing bias and variability because of multiple raters and simplifying calculation and interpretation. Appropriate...

Estimates of service life are increasingly used to compare life cycle costs of building materials. Because of a lack of published data for treated wood, some users assume a relatively low service life for wood in comparison to alternative materials. Such bias against durable wood products may cause alternative materials to appear more economical. This paper discusses options for making additional treated wood service life information available to engineers and others who are comparing construction materials. In the short term, existing data and reports could be summarized and published in...