Phenol Adhesive Bonded Medium-Density Fiberboard From Quercus Rubra L. Bark and Sawdust

Twelve-millimeter-thick medium density fiberboards made from double-disc, steam-pressure-refined red oak sawdust fibers at 6.5 and 9.0% phenol-formaldehyde levels for both, with and without the addition of sodium pentachlorophenate, meet most of the specifications required for exterior-grade, medium density, class 1 commercial particleboard and medium density hardboard. Panels made from red oak bark fibers showed inferior properties to panels made from red oak sawdust fibers. However, at a 9% resin level, untreated bark fiberboard exhibited acceptable modulus of elasticity in bending, internal bond, and face screw-holding values. The addition of the preservative to the adhesive had the effect of decreasing all of the strength properties and the linear expansion values of all untreated panels at three resin levels.Three-layer type of panels made from red oak sawdust fiber faces and red oak bark fiber core had higher bending strength, stiffness, and face screw-holding values, but lower internal bond and tensile strength parallel to face values than a homogeneous type of panel made from a mixture of equal weight of sawdust and bark fibers. Three-layer panels also showed lower linear expansion values than the homogeneous type of panel. At a 6.5% resin level, both homogeneous and three-layer types of panels had acceptable strength properties except for the tensile strength parallel to face and linear expansion values

Carbon and Hydrogen Contents of Short-Rotation Biomass of Five Hardwood Species

Carbon, hydrogen, and ash contents were determined on three-year-old, short-rotation trees of autumn olive, black alder, black locust, eastern cottonwood, and sycamore. These plantations were established on marginal agricultural land that was not suitable for food production in Midwestern United States. Test results indicated that elemental analysis varied among species, planting site, and spacing. Black locust had the highest hydrogen content, black alder had the highest carbon content, and eastern cottonwood possessed the greatest ash content. The hydrogen content was higher at bottomland than upland, while the carbon content and ash content were both higher on upland as opposed to bottomland sites. The hydrogen content was higher at narrow spacing, while carbon content was higher at wide spacing. Conversely, hydrogen was not significantly affected by the stem portion, while both carbon and ash contents of the wood, bark, and branches mixture portion were higher than those of the wood portion

Fuel Characteristics Of Selected Four-Year-Old Trees In Nigeria

With the rising cost and decreasing availability of fuelwood, fossil fuels, and fossil-based chemical feedstock in the future, there is renewed interest in using renewable, plantation-grown, tropical wood biomass as an energy source or chemical feedstock. There is, however, a lack of information on the basic fuel characteristics and chemical constituents of short-rotation, juvenile, tropical wood biomass. Content of hot-water extractive, alcohol-benzene extractive, lignin, gross heat, sulfur, and ash were determined for the samples, as well as specific gravity and results of the proximate analysis (volatile matter, ash, and fixed carbon), and the ultimate analysis (C, H, N, S, O, and ash). These properties were determined on five short-rotation tree species, a tree nut-shell, and a commercial bituminous coal. Test specimens included stems of four-year-old gmelina, eucalyptus, cassia, teak, gliricidia, and nut-shells of tetracarpidium trees all grown in Nigerian fuelwood plantations near Ibadan. Based on chemical and fuel composition, most of the juvenile tropical species and the tree nut-shells could serve as a raw material for energy in fuelwood and charcoal industries, as well as for chemical industries

Effects of Load Level, Core Density, and Shelling Ratio on Creep Behavior of Hardboard Composites

Sustained load bending tests were conducted on large size 3/4-inch-thick, 12-by 39-inch red oak veneered-hardboard composites, hardboards, and red oak lumber. A greater initial elastic deflection generally resulted in a greater total creep and irrecoverable creep deflections. Creep deflections of all composite panels were affected by the load level, core density, and shelling ratio in this study. The red oak lumber exhibited the most creep resistance. However, the composite panel with a shelling ratio of 0.262 was nearly as resistant to creep as red oak lumber. Creep deflections of all composite panels were very well described by a power-law function, based on two separate test models of 2 to 10 min and 10 to 100 min. The extrapolation of log-log regression for the approximation of creep appeared to give reasonable values for up to three weeks. Three multivariable regression models were developed to predict the initial, total, and irrecoverable creep deflections as a function of shelling ratio, load level, and hardboard core density. Their R2 values were 0.96, 0.87, and 0.85, respectively

The Effect of Pressure on Retention and Bending Properties of Copper Naphthenate and CCA Type C Treated Hardwoods

The objective of this study was to investigate the effect of the pressure level on retention and bending strength of some northern hardwood species after preservative treatment. Samples of red maple, sugar maple, beech, and red oak were pressure-treated with waterborne chromated copper arsenic (CCA) type C or with oilborne copper naphthenate (Cu-N) at four pressure levels: 0.69, 1.03, 1.38, 2.07, and 2.76 MPa. At a pressure level of 0.69 MPa (200 psi) for 2 h, retentions of 4.5 kg/m3 elemental copper from copper naphthenate and 10 ± 2 kg/m3 total oxides from chromated copper arsenate (CCA) were achieved for maples. The pressure level did not affect the retention of Cu-N in red maple, sugar maple, and red oak; the same observation was made for CCA in maples. A pressure level of 2.76 MPa was needed to obtain a 7.5 kg/m3 CCA retention and 1.08 kg/m3 copper metal in Cu-N-treated beech. Copper naphthenate treatment did not affect the bending strength, while CCA-treated samples exhibited a reduced bending strength between 0 and 33% depending on the species, pressure level, and preservative type

Chemical Compositions of Five 3-Year-Old Hardwood Trees

Contents of lignin, pentosan, holocellulose, and alpha-cellulose were determined on 3-year-old trees of autumn olive, black alder, black locust, eastern cottonwood, and sycamore. These plantations were established on marginal agricultural land in the Midwestern United States that was not suitable for food production. Test results indicated that chemical properties did vary among species, planting sites, spacing, and tree portion. Trees grown on upland sites gave significantly higher values for lignin, pentosan, and holocellulose content. The narrowly spaced trees gave higher values for pentosan content. The widely spaced trees gave higher values for lignin, holocellulose, and alpha-cellulose content. The mixture tree portion contained higher amounts of lignin. The wood portion contained more pentosan, holocellulose, and alpha-cellulose. Autumn olive had the highest lignin content. Sycamore had more pentosan and holocellulose. Black locust had the highest alpha-cellulose content. The results indicated that the five 3-year-old deciduous species examined could serve as a raw material for the rayon and polymer industries, as well as for liquid fuel

The Internal Bond and Shear Strength of Hardwood Veneered Particleboard Composites

The effects of several accelerated aging tests and weather exposures on hardwood reconstituted structural composite panels were evaluated. The results indicated that the internal bond and shear by tension loading strength reductions of the panels were affected by the exposure test method. The ranking of the effects of various exposure tests on strength values in an increasing order of severity was (1) 24-hour soak, (2) 1-hour boil, (3) 2-hour boil, (4) ASTM-6 cycles, and (5) WCAA-6 cycles. Both ASTM and WCAA tests had similar influences on IB and shear strength properties. Also, 4 cycles of either of these tests resulted in about the same degree of strength reduction as 6 cycles. In addition to test methods, a few construction variables were evaluated. The type of glueline, dry phenolic resin film and wet melamine-urea formaldehyde resin used to laminate the veneer over the core material yielded similar strength values. Other construction variables evaluated indicated that panels with an exterior particleboard core made from smaller particles as compared to wafers had higher IB values than waferboard core panels

Some Chemical Constituents of Ten-Year-Old American Sycamore and Black Locust Grown In Illinois

Research was initiated to determine the effects of site (upland, bottomland) and tree origin (seedling, coppice) on the chemical composition of wood of two, ten-year-old hardwood species grown in Illinois. Ten-year-old black locust (Robinia pseudoacacia L.) and American sycamore (Platanus occidentalis L.) were evaluated for alcohol-benzene extractives, hot-water extractives, one-percent NaOH extractives. Klason lignin, holocellulose, and alpha-cellulose. Black locust had statistically higher alcohol-benzene extractives, hot-water extractives, and alpha-cellulose content than sycamore. A relationship between wood density and alpha-cellulose exists. Black locust yielded a higher mean Klason lignin value, and sycamore yielded a higher mean one-percent sodium hydroxide value hut the difference was not significant at the α = 0.05 level. The effects of site and origin were inconsistent for the different chemical properties. Black locust appears to be a favorable species for a variety of chemical constituents and can be successfully grown under different silvicultural methods