Treesearch

Several non-intrusive synchrotron techniques are being used to detect and study wood decay. The techniques use high intensity synchrotron-generated X-rays to determine the atomic structure of materials with imaging, diffraction, and absorption. Some of the techniques are X-ray absorption near edge structure (XANES), X-ray fluorescence spectroscopy (XFS), X-ray absorption fine structure (EXAFS), and X-ray computed microtomography (XCMT). Micro-fluorescence spectroscopy was used to map the accumulation and spatial distribution of elements around hyphae at the site of decay. MicroXANES...

About 160 fewer softwood sawmills are operating in the United States and Canada than were 8 years ago. Nevertheless, the combined capacity of the remaining mills has increased by 16%, to over 173 million cubic meters. Of the approximately 1,140 mills, about 470 characterize their output as dimension lumber, accounting for 67% of capacity; 136 list studs as their primary output, representing 16% of the industry's volume; and 139 are primarily board mills, making up a little over 5%. The others make a variety of specialty products. In this report, the location and relative size of sawmills...

Urban tree and woody yard residues are an important component of the municipal solid waste (MSW) stream in the United States. In 2000, approximately 14.5 million tons of urban tree and woody yard residues was generated, nearly 7% of total MSW. Some woody residues are being recovered for recycling, composting, or other uses, but a large proportion is simply discarded. In total, urban tree and woody yard residues form a resource about as large or larger than the current timber harvest from National Forests. Materials from each of these two sources have distinctly different properties and, in...

Wood-plastic lumber is promoted as a low maintenance high-durability product. When exposed to accelerated weathering, however, wood-plastic composites may experience a color change and/or loss in mechanical properties. Different methods of manufacturing wood-plastic composites lead to different surface characteristics, which can influence weathering, In this study, 50% wood-flourfilled high-density polyethylene (HDPE) composite samples were injection molded, extruded, or extruded and then planed, to remove the manufacturing surface characteristics. Fourier transform infrared spectroscopy...

Unlike their glass reinforced counterparts, microstructure and dynamic fracture behavior of natural fiber-reinforced thermoplastics have hardly been investigated. Here, we characterize the microstructure of cellulose fiber-reinforced polypropylene and determined its effect on impact toughness. Fiber lengths were reduced by one-half when compounded in a high-intensity thermokinetic mixer and then injection molded. At low fiber contents, injection molded specimens showed little fiber orientation; at high fiber contents, a layered structure arose exhibiting differing fiber orientations...

Dynamic mechanical analysis was employed to evaluate the performance of various natural fibers in high-density polyethylene composites. Kenaf, newsprint, rice hulls, and wood flour were sources of fiber. Composites were made at 25 percent and 50 percent by weight fiber contents. Maleic anhydride modified polyethylene was also added at 1:25 ratio to the fiber. Temperature scans in the range of -110° to +100°C were performed, and storage modulus, loss modulus, and mechanical loss factor (tan 6) were recorded over the selected temperature range. Different transitions were monitored, and the...

Woodfiber-thermoplastic composites (WPC) have received considerable attentions from the forest product industry for civil engineering applications due to its superior properties over wood and plastics alone. Particularly WPCs can be easily fabricated using traditional plastic processing techniques. The major limitation in the applications of WPCs is the poor understanding of their mechanical properties and especially the environmental impacts on these properties. The aim of this research is to systematically study the mechanical properties of aspen-fiber polypropylene composites (APCs),...

Some engineered wood fiber (EWF) surfaces on playgrounds are soft and uneven, which creates difficulties for those who use mobility aids, such as wheelchairs and walkers. The outdoor field testing reported in this study is part of an effort to stabilize EWF to improve accessibility. The concept is to mix a binder with the upper surface of EWF to create a stiff (firm) and scuff-resistant (stable) composite overlayer. Latex, silicone, and polyurethane binders were evaluated on small plots during a 6-month outdoor trial in Wisconsin. Tests were performed at regular intervals to provide a...

The paper reviews the processing advantages and challenges of microcellular injection molding and presents recent research results on applications of nanocomposites and woodfiber-plastic composites as well as new process develop for the microcellular injection molding process. In particular, two types of polyamide (PA-6) neat resins and their filled counterparts, such as a PA-6/ montmorillonite nanocomposite, a cellulose- fiber-reinforced PA-6 composite, and a hybrid PA- 6/cellulose/Wollastonite composite, were injection molded into ASTM test-bar samples with both conventional and microcell...

During outdoor exposure, woodfiber-plastic composites (WPC) are subject to biological, moisture, and ultraviolet (UV) degradation. The purpose of laboratory evaluations is to simulate outdoor conditions and accelerate the testing for quicker results. Traditionally, biological, moisture, and W laboratory tests are done separately, and only combined in outdoor field exposure. This research evaluates WPCs exposed to a combination of UV, moisture, and fungal degradations. Due to the slow moisture sorption of WPCs, the ASTM D 1413 standard laboratory soil block test was modified to include...