Density oven-dry

In studies of plantation forest species it is eommon praetiee to earry out surveys of wood density (and other properties) by means of 5 mm diameter inerement core samples at breast height. Often the unextraeted wood density (oven-dry wood substances plus the extraetives) is quoted in the literature. 

Specific gravity is direcdy related to the bulk density of waste fuels prepared ia a variety of ways. Solid oven-dry (OD) wood, for example, has a typical bulk density of 48.1 kg/m (301b/ft ). In coarse hogged form, eg, <1.9-cm minor dimension, this bulk density declines to about24kg/m (151b/ft ). In pulverized form, at a particle size <0.16 cm, this bulk density declines to 16—19 kg/m (10—12 Ib/ft ). Similar relationships hold for municipal waste, agricultural wastes, and related fuels. 

Wet weight was recorded on site for LUV, HUV, and LI fractions. Dry weight was determined in the lab (registered after drying in an oven at 80°C until constant weight). The equation introduced by Cairns and coworkers [31], for tropical forest and lower latitudes than 25°, was used. The AGB fraction, also called as "biomass density" when expressed as tons of oven-dried... 

Calculation. Ash-free fulvic acid y mg 100 ml is read from the chart. This solution resulted from 10 g air-dry soil in 250 ml solution. Therefore 250 ml solution contains yx 250/100 mg fulvic acid from 10 g air-dry soil, which converts to 25y mg fulvic acid 100 g or 0.025y% air-dry soil. This must be multiplied by any dilution factor before reading the optical density, also converted to percent oven-dry soil (see Method 5.2, Calculation (2)). 

Density, Air-Dry, grams gallic add equiv./ gram/cmz 100 grams Oven-Dry)... 

Composite formulations were prepared as follows The straw samples as received from INEEL were ground to 0.69 mm in a hammer mill and oven dried to 1.1% moisture. The dried straw samples were then blended with various amounts of high-density polyethylene (HDPE), lubricants, and maleated polyethylene blends (MAPE) (see Table 2). The mixed formulations were then extruded with a 35-mm Cincinnati Milacron Model CMT 35 counterrotating conical twin screw extruder (Cincinnati Milacron, Batavia, OH), which produced a 9.525 x 38.1 mm2 solid cross-section. Flexural strength, density, and water sorption were measured for the extruded samples according to ASTM Standard Methods (13,14). 

After the boards were removed from the hot press they were conditioned at room temperature for several days before testing. Three 2 x 10-inch strips were cut from each board for determining breaking load. A 0.24-inch-per-minute loading rate and a 9-inch span were used. Thickness of each strip was measured at the point where the load was to be applied, and after the strip had been "broken each half was cut into two 2 x 2-inch samples. These samples were used to obtain data necessary for determination of oven-dry density, water absorption and thickness swelling, internal bond, and a 2-hour boiling-in-water thickness swelling test. 

After the extraction is completed, typically the specimen is removed and measured to calculate its volume, weighed and oven dried at 105 °C for density and moisture content determinations. 

Soil bulk density (g cm ) Mass of oven dry soil/volume of soil core... 

Experimental load deflection curves (Fig. 3.) illustrate the large difference in crack propagation observed in each case. A difference in stiffness between both bonded specimens is observed and results from either a difference in the bond line quality or from interfacial conditions. For both specimens, adherends were made from the same sample of wood. Both wood substrates contained no apparent defects and had the same longitudinal Young s modulus (14500 MPa). Both also had the same growth characteristics (oven dry specific density, annual growth rings), and as a consequence very close values of transverse and shear modulus adjacent to the bond line. Thus, any difference in stiffness is likely to be due to... 

Specific Gravity and Density. The decrease that occurs in specific gravity with an increase in moisture content was discussed in connection with wood swelling. The specific gravity decreases with increasing moisture content up to fiber saturation but above this there is no change because the volume remains constant and the weight is based on the oven-dry condition. 

Species /V oven-dried wood) Density (glen/) IB (psi) Thickness Swelling Water Absorption (%) (%) ... 

Conditions Activator, 1.5% HNO3 (72%) (oven-dry basis) cross-linldng agent, 7% (oven-dry basis), composed of 60% ammonium lignosulfonate, 25% furfuryl alcohol, and 15% maleic anhydride target density, 0.65 g/cm bonding, 7 min at 177 °C with 9-11% moisture content of the material. 

Three separate measurements are needed to define unambiguously the density of wood the mass and volume of the wood at x % moisture content and the oven-dry mass (drying to constant weight at 103°C). The latter value is needed to specify the moisture content at which the density was determined. Three specific definitions follow ... 

Thus, if the green density of a piece of wood at 50% moisture content is 600 kg m its nominal density will be 400 kg m . The wood will contain 400 kg m of oven-dry material per cubic metre of green wood. 

The term basic emphasizes that both the parameters measured, the oven-dry mass and the swollen volume, have constant and reproducible values. Basic density is the most useful descriptor of wood density. 

The density of oven-dry cell tissue of all woody plants is roughly 1500 kg m. It can be accurately determined with a pycnometer, a small vessel (c. 10 ml) with a ground glass stopper having a concentric capillary bore to allow excess liquid to escape when filling the vessel. The pycnometer can be filled with a highly reproducible... 

The difference between the oven-dry cell wall density determined using silicone and after solvent exchange using an inert liquid like hexane must be due to the presence of residual sub-microscopic pores within the oven-dry cell wall, that are only penetrated when the cell wall is swollen. Accordingly, the inaccessible void volume per kg of cell wall material can be determined from the difference between the apparent volume of the cell wall material in silicone and the true volume as measured in the solvent-exchanged hexane. This is 0.0303 x 10 m per kg, or about 4% on a volume basis, i.e. (0.0303/0.6825) x 100% (Table 3.2). 

Wood contains air and water as well as wood substances. Wood, when oven-dry, contains only air and woody tissue. The oven-dry density of any species is a direct reflection of the amount of space occupied by wood tissue. Wood densities can vary from 50 kg m with balsa (Ochroma lagopus) to 1400 kg m with lignum vitae (Guaiacum officinale), although most commercial species have densities between 350 and 800 kg m. The proportion of air space to total wood volume can be estimated from the oven-dry density of the timber. Consider a timber having an oven-dry density of 500 kg m . A cubic metre of such a timber would contain 500 kg of woody material whose density is roughly 1500 kg m . This means that the wood substances occupy some 0.33 m leaving 0.67 m " as air space, i.e. two-thirds of the volume is air space. This calculation emphasizes the porosity of most dry wood. 

The maximum moisture content for a wood can be estimated easily. In a timber having a basic density of 300 kg m the oven-dry cell tissue (density 1500 kg m )... 

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