Wood and Fiber Science (E-Journal)
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Heating Performance of Frozen Lodgepole Pine Lumber
Get PDFThis study was undertaken to determine the heating process of frozen lodgepole pine (Pinus contorta) lumber because many regions in Canada have to heat-treat or dry frozen lumber in the winter. Because phytosanitary regulations require that lumber products be heat-treated before delivery to customers (core wood temperature of 56°C for 30 min), it is important to determine the time required to reach this criterion. In this study, 10 heating runs were made with different initial moisture contents (MCs) and temperatures using a laboratory kiln humidified with low-pressure steam or cold water spray. To simulate the performance of frozen lumber, the existing heating model for unfrozen lumber was modified by adding a phase-change analysis and was verified using the data from laboratory experiments. The experimental results combined with the model predictions indicated that the thawing time was increased for frozen lumber with higher initialMC. The modified model satisfactorily estimates heating times for frozen lodgepole pine lumber
Determining the Mechanical Properties of Microcrystalline Cellulose (MCC)-Filled PET-PTT Blend Composites
Get PDFPolymer composite materials consisting of poly(ethylene terephthalate) (PET)-poly(trimethylene terephthalate) (PTT) blends and microcrystalline cellulose (MCC) were prepared by injection molding. The composites were analyzed for tensile, flexural, and impact strength as well as density determinations. There was no statistical difference in terms of mechanical properties between the control PET-PTT blend and 2.5 wt% MCC-filled composites. Because of better compatibility as well as better stress-transfer properties, the tensile strength of the composites was larger (reaching values from 24.8-36.3 MPa with the addition of 20 wt% MCC). Elongation at break of the composites was greater (reaching values from 2.3-3.3% with the addition of 20 wt% MCC). The tensile modulus of MCC-filled composites systemically increased with increasing MCC loading (reaching values from 1.11-1.68 GPa with the addition of 30 wt% MCC). The flexural modulus of composites was higher than the control PET-PTT blend. The modulus also increased with increasing MCC loading (reaching values from 2.10-3.37 GPa with the addition of 30 wt% MCC). The Izod impact strength of the composites decreased as the MCC loading increased and this observation was in good agreement with commonly observed filled polymer systems
Technical Note: Responses of Vertical Sections of Wood Samples to Cyclical Relative Humidity Changes
Get PDFThis study investigated moisture responses of the surface, middle, and central portion in the thickness direction of wood samples to cyclic RH changes. Phase lag and amplitude for these sections were determined quantitatively by Fourier analysis. These data were used to suggest a mechanism for the unexpected phenomenon that moisture changes are slower than dimensional changes found in previous work
Life Cycle Inventory of Softwood Lumber from the Inland Northwest US
Get PDFAs part of CORRIM Phase II life-cycle inventory (LCI) studies on forestry and wood products, this study completed a gate-to-gate life LCI for the production of softwood lumber produced in the Inland Northwest region of the US. Data were collected by surveying representative softwood lumber producers. Raw material use, heat energy, fuels, electrical consumption, and associated wood production emissions represented input data into the LCI. The combined annual production of the representative softwood manufacturers was 16% of the total annual regional production of 755,852 m3. Thermal energy requirements made a significant contribution to the total energy consumption for wood production. In this study, approximately 72% of the total energy was used for drying green lumber to 15% MC. Thermal energy was generated both from wood fuel and natural gas, representing 54 and 46% of the total, respectively
Technical Note: Effect of Soil on the pH of Treated Wood in Ground Contact
Get PDFThe pH of treated wood in ground contact will influence the type and activity of decay and nondecay microorganisms present as well as the solubility and leaching of metallic biocides. To determine the soil effect on the pH of treated wood in ground contact, southern pine sapwood samples commercially treated with five copper-based preservatives along with untreated pine were placed in pots filled with five different soils. The pH of the wood samples after a 12-wk exposure to basic soils increased, as anticipated. However, the pH of wood in acidic soils was more complex than expected with the treated wood pH always greater than soil pH. Two possible chemical mechanisms to explain the nonintuitive results for treated wood in acidic soils are given
Effect of Tie-Layer on the Bond Strength Between Thermoplastic and Borate-Treated Wood Substrate
Get PDFA challenge in using wood or wood composites for exterior applications is durability. Borate-treated wood substrates are durable if leaching of the chemical over time can be reduced to acceptable levels. The goal of this project was to encapsulate borate-treated structural wood and wood-based composites with thermoplastic to extend their durability. In this study, the efficacy of two tie-layers (maleic anhydride modified high-density polyethylene and styrene-butadiene polymer) in bonding high-density polyethylene (HDPE) to treated wood substrate was examined together with determining the ideal hot-press parameters necessary to achieve a good bond. Boric oxide treated Douglas-fir and southern pine Parallam® and untreated Douglas-fir solid wood were the substrates investigated. The optimum processing parameters were 180°C platen temperature, 1035 kPa press pressure, and 300 s press time. Bond strength was determined by conducting a 90° peel test and a block-shear test. Durability of the thermoplastic barrier layer was evaluated by subjecting specimens to an accelerated aging test and reevaluating the bond strength. Maleic anhydride-modified HDPE tie-layer yielded improved bond strength that was durable, especially when bonded to a treated southern pine substrate
Effects of Composite Processing Methods on Wood Particle Development and Length Distribution: Consequences on Mechanical Properties of Wood-Thermoplastic Composites
Get PDFThe relationship between structure and properties of high-density polyethylene (HDPE) filled with wood particles and processing techniques—injection molding, compression molding, and extrusion—was investigated. Wood particles were hammer-milled, sieved, and compounded into pellets at 35% by weight with HDPE using a twin-screw extruder. Coupling agent (ethylene-maleic anhydride copolymer) was added at 2% by wood filler weight. The pellets were used to produce test samples using the three processing techniques. The sensitivity of jack pine and several other wood particles (eastern white cedar, black spruce, and jack pine bark) to composite processing was analyzed. Bark particles showed higher propensity to generate fines than wood particles, possibly because of a higher thermal sensitivity. The major reduction in mean particle length was found to occur in the compounding process. Extrusion and injection molding contributed to particle length reduction to a lesser extent. Conversely, compression molding did not cause significant damage to wood particles. Stiffness and strength increased linearly with weight-averaged length
Life-Cycle impacts of Inland Northwest and Northeast/North central forest resources
Get PDFDetermining the life-cycle inventory (LCI) and impact of forest harvest, regeneration, and growth is necessary in conducting a life-cycle assessment of wood products. This publication provides quantitative assessments of the economic and environmental impacts of forest management activities covering portions of the Inland Northwest (INW), including Montana, Idaho, and eastern Washington, and of the Northeastern and North Central (NE/NC) forests from Minnesota to Maine and south as far as Missouri, West Virginia, and Pennsylvania. The management scenarios provide the inputs needed to develop an LCI on all the inputs and outputs for wood products as impacted by forest treatments and the harvesting of logs in the region. Productive timberlands were grouped according to forest type, productivity, management intensity, and ownership into three broad forest types in the west: cold, dry, and moist; and four in the east: spruce/fir, northern hardwoods, oak/hickory, and aspen/birch. Spruce/fir represented the feedstock to softwood lumber and a composite of northern hardwoods and oak/hickory the feedstock to hardwood lumber. Simulations used the US Forest Service Forest Vegetation Simulator to estimate standing and harvested biomass and log volumes passed on as resources to the manufacturing segments for lumber, plywood, or oriented strandboard. The combinations of ownership, management intensity, and forest type were stratified and averaged to produce a single estimate of yield and the corresponding harvesting impacts. Both historic harvest rates and increased management intensity scenarios were simulated for each region. In the INW, the shift to the higher intensity scenario increased the average production of merchantable volume at harvest to 249 - 399 m3/ha when averaged across the forested land in each ownership class. For the NE/NC region, the production of merchantable volume averaged 263 m3/ha for softwood and 328 m3/ha for hardwood forests with an insignificant volume response from shifting land into more intensive management. Average growth varied widely for INW forest categories from a low on federal land for the base case of 0.7 - 6.7 m3/haha·yr for moist state and private land under the intensive management alternative. Current condition estimates of softwood log and bark carbon exported for mill processing in the INW and NE/NC regions were 751 and 988 kg/ha·yr, respectively
Integrating Products, Emission Offsets, and Wildfire into Carbon Assessments of Inland Northwest Forests
Get PDFForest inventory and harvest data from life-cycle inventory and life-cycle assessment for the forest resources of the Inland Northwest region covering Idaho, Montana, and eastern Washington were used to estimate the impacts of management action on the full suite of carbon accounts that can accrue from forest management. The carbon accounts include the forest, wood products, the benefit gained from using wood products as substitutes for alternative products that are fossil fuel-intensive to produce, and the displacement value of using woody biomass to replace fossil fuel. A landscape-level assessment of projected carbon storage by owner group shows that in 100 yr, management on State and Private Forests can sequester or avoid emissions equal to 294 t/ha of carbon, which equals over 1.9 Gt of carbon across 6.5 Mha. Seventy-nine percent of the carbon accumulates beyond current forest carbon inventories. On National Forests, carbon sequestration and avoided emissions are 152 t/ha over 11 Mha of unreserved forests equaling 1.4 Gt of carbon under predictions for a doubling of the 20th century fire rate. The carbon storage in buildings and the substitution benefits override the potential gains of attempting to leave high carbon stocks stored in the forest in this region where disturbance from fire and insect outbreaks dominates the forest ability to sequester carbon