Treesearch

This study evaluated physical, mechanical and fire properties of oriented strand boards (OSB) covered with fire retardant treated veneers. The beech (Fagus orientalis Lipsky) veneers were treated with either monoammonium phosphate, diammonium phosphate, lime water or a borax/boric acid (1 : 1 by weight) mixture. Physical and mechanical properties of the specimens were performed according to EN and DIN standards. A cone calorimeter was used to determine their combustion characteristics. The physical and mechanical properties of the specimens were adversely affected by the treatments. The...

Hot melt and water-based adhesives are very different materials with similar physical properties. Their ability to act as adhesives is due to physical bonds and mechanical interlocks which form as adhesive flows into topographical features on the substrate surface. Hot-melt adhesives are based on soft, rubbery polymers while water-based adhesives are usually acrylic latex emulsions. Both of these materials are soft and weak resulting in adhesive fragmentation during repulping. We have previously successfully modeled the behavior of hot-melts. The formulation and structure of water-based...

Ultraviolet radiation, moisture, heat, and cyclic fatigue are some of the stressors that cause materials to degrade outdoors. Considerable research has addressed the effects of ultraviolet radiation and moisture on the rate of this degradation. An often overlooked stressor on materials, during outdoor testing, is the cyclic fatigue. Cyclic fatigue is caused by self-induced dimensional change of a material or by dimensional change of materials in contact with it. For example, changes in the moisture content of wood cause it to shrink and swell, which leads to surface checking; dimensional...

FT-IR microscopy was used to depth profile the photodegradation of Japanese cedar earlywood exposed to monochromatic light in the UV and visible ranges (band pass: 20nm). Parallel experiments assessed the transmission of the light through thin sections of Japanese cedar. The depth of photodegradation increased with wavelength up to and including the violet region of the visible spectrum, but decreased in the blue region. In contrast, penetration of light into Japanese cedar was positively correlated with wavelength. We concluded that violet light has sufficient energy to degrade wood and...

This section presents three basic methods for deriving and documenting Rn as an LTL value along with the coefficient of variation (COVR) for single-pole structures. These include the following: 1. An empirical analysis based primarily on tests of full-sized poles. 2. A theoretical analysis of mechanics-based models used in conjunction with Monte Carlo simulation. 3. A default assignment of material distribution parameters.

We can have the greatest direct impact on petroleum and natural gas fuel usage by burning or gasifying wood for space heat, process energy and power. One alternative source that is available and underused is surplus wood. Certainly wood that is suitable for use in more valuable products should not be diverted to energy use that provides less income; however, other wood is unused or even burned or landfilled for disposal. Such wood is well suited for energy applications.

Interest in the use of nanoparticles of iron, titanium, aluminum, and zinc oxides in transparent coatings for wood is increasing. Such nano-composite coatings have the potential of not only preserving the natural color of the wood but also stabilizing the wood surface against the combined degradative effects of sunlight and moisture. The nanoparticles can be used as additives to coating formulations or deposited directly as thin films on a substrate. Thin film deposition can be accomplished by plasma-enhanced chemical vapor or by sol-gel deposition. This paper describes sol-gel deposition...

SilviScan uses X-ray transmission measurements along with optical imaging to profile tracheid dimensions and wood density in specially prepared cores. These measurements are useful for predicting the properties of pulp and paper generated from the wood. SilviScan measurements are resolution-limited by the width of the X-ray beam, which was 50 m in the present study. Trees with growth rings smaller than 200 m have latewood regions too small to measure without sampling adjacent earlywood, producing erroneous latewood measurements. For these suppressed-growth trees, we developed an all-optical...

Eocene terrestrial strata of central Oregon contain abundant and well-preserved fossil woods that are important for understanding past floristic diversity, forest structure, and climate. In addition to the remarkably diverse and well-preserved Middle Eocene wood assemblage of the Clarno Nut Beds in the type area of the Clarno Formation in the John Day basin, there are well-preserved diverse Late Eocene wood assemblages from the vicinity of Post in the Crooked River Basin. The Post assemblages discussed herein share some genera with the Nut Beds flora (Acer, Cercidiphyllum, Quercinium,...

The macroscopic behavior of paper is governed by small-scale behavior. Intuitively, we know that a small-scale defect with a paper sheet effectively determines the global behavior of the sheet. In this work, we describe a method to evaluate the local constitutive behavior of paper by using an inverse method.