Treesearch

Wood has several levels of hierarchical structure, spanning from the configuration of growth-rings down to the configuration of the base polymers (cellulose, hemicellulose, and lignin). The bulk properties of wood result from the culmination of interactions over all length scales. Gaps presently exist in the fundamental knowledge relating the contribution of wood properties at each structural level to the resulting bulk properties. The advent of nanoindentation has facilitated mechanical property measurement at the cell wall layer; however, there is limited understanding of how and to what...

The role of reactive oxygen species (ROS) in electrochemical biofouling inhibition was investigated using a series of abiotic tests and settlement experiments with larvae of the barnacle Amphibalanus amphitrite, a cosmopolitan fouler. Larval settlement, a measure of biofouling potential, was reduced from 43% ± 14% to 5% ± 6% upon the application of pulsed electric signals. The application of ROS scavengers such as glutathione and catalase counteracted the inhibitory effects of the electric signals, allowing settlement, and thus indicating that ROS are antifouling agents. Based on the...

Several different studies are compared to assess the effectiveness of commercial water repellent preservatives (WRP’s) in the late 1990’s on vertical and horizontal siding. Besides WRP, variables included wood species, exposure location (Wisconsin or Mississippi), and solid color stain vs. primer + paint. Data on substrate checking and paint flaking are presented. Painting end grain of vertical siding was universally helpful. Appropriate WRP’s on end grain universally improved performance, even when end grain was primed and painted. WRP applied to entire boards had mixed results. Any...

Predicting the service life of building joint sealants exposed to service environments in less than real time has been a need of the sealant community for many decades. Despite extensive research efforts to design laboratory accelerated tests to duplicate the failure modes occurring in field exposures, little success has been achieved using conventional durability methodologies. In response to this urgent need, we have designed a laboratory-based test methodology that used a systematic approach to study, both independently and in combination, the major environmental factors that cause...

A computer-controlled test apparatus (CCTA) and other instrumentation for subjecting sealant specimens to cyclic fatigue during outdoor exposure was developed. The CCTA enables us to use weather-induced conditions to cyclic fatigue specimens and to conduct controlled tests in-situ during the outdoor exposure. Thermally induced dimensional changes of an aluminum bar were fed to a computer that enhanced the movement, set limits on the movement, and supplied movement information to the test apparatus. As specimens moved, load/deformation and weather conditions (temperature, relative humidity,...

The influence of local microstructure on the fracture process at the crack tip in a ceramic–metal composite was assessed by comparing the measured stress at a microstructural level and analogous finite element modelling (FEM). Fluorescence microprobe spectroscopy was used to investigate the influence of near-crack-tip stress fields on the resulting crack propagation at the microstructural scale. The high spatial resolution was effective at mapping the localized crack-tip stress distributions within the complex Al–Al2O3 phase morphologies, where the localized stress distribution about the...

Soy flour is an inexpensive raw material for adhesives and is readily available in most parts of the world. However, converting soy flour into a wood adhesive that can compete in both cost and performance with existing petroleum-based adhesives is not easy given the variables of flour quality, denaturation conditions, and curing methods. Formulating adhesives that alter these variables is more readily accomplished than is testing the performance of these formulations using standard evaluation methods. To overcome this problem, we developed a rapid and reproducible small-scale bond strength...

Outdoor weathering of wood specimens treated with sol-gel formulations based on methyltrimethoxysilane (MTMOS), hexadecyltrimethoxysilane (HDTMOS), and ferric-zirconia-titania (Fe-Zr-Ti) sol was evaluated. The sol-gel process allowed deposition of a thin film of hybrid inorganic-organic networks (gel) in the wood cell wall that resulted in improved outdoor weathering properties. The sol-gel-treated specimens showed better color retention compared with non-treated control specimens after one-year exposure outdoors. However, in terms of uniformity of color retention, the general appearance...

Conductance moisture meter readings using stainless steel screws as electrodes were compared with gravimetric moisture content for 1) southern yellow pine (SYP) dimensioned lumber, 2) untreated (underlayment grade) SYP plywood, and 3) SYP plywood treated with alkaline copper quaternary. Meter readings were taken with the meter set to the manufacturer-provided species correction for SYP. In the sample of dimensioned lumber used in this investigation, direct meter readings corresponded closely with gravimetric moisture contents. The manufacturer-provided correction for SYP wood was thus...

This study evaluated the ability of pressure treatments with a borax–copper (BC) preservative to protect wood exposed above ground or in contact with the ground. Stake testing indicated that the 2.3% and 4.7% BC concentrations were fairly effective in preventing decay in Wisconsin but were not effective in protecting stakes exposed in Mississippi. The 1.4% and 2.3% BC concentrations effectively protected decking specimens exposed for 5 years at the Wisconsin test site. Assay of stakes at the Wisconsin site indicated that over 90% of boron in the below-ground portion of the stakes was lost...