Wood samples

In order to expand the chemical sampling of this species to its entire range and to investigate xylem terpenoids in detail, Zavarin et al. (1990) collected wood samples from 191 trees from 20 areas, isolated the monoterpene fractions, and subjected them to GLC analysis. The major component was identified as a-pinene, with P-pinene, 3-carene, and limonene as lesser, but stiU important, components. Minor... 

Classify each of the following as an intensive or extensive property of the wood samples a. color b. smell c. grain pattern of the wood d. mass e. volume and f. density. Provide justification for your classification. 

See for example, from the 19th International Radiocarbon Conference held in 2006 A.G. Hogg, L.K. Fifield, J.G. Palmer, C.S.M. Turney and R. Galbrait, Robust radiocarbon dating of wood samples by high sensitivity liquid scintillation spectroscopy in the 50 70 kyr age range, Radiocarbon 49,379 391 (2007). 

Similar studies were conducted by Kudzin and Nord (64) on the hardwoods oak, birch and maple. The fungus employed to bring about the decay of these wood samples was Daedalea quercina. The results of the periodic analyses of the decayed wood and the chemical compositions of the alcohol extractable lignins are outlined in Tables 6 and 7 respectively. 

Figure 8.8 Pyrolysis-front propagation velocity vp, and flame-tip propagation velocity Vf, as functions of the incident radiant energy flux, for a preheat time p of 2 min on a wood sample [13]...

As one can see from distribution of Cd concentration values in deciduous trees, there are three separate sections in this line. The first one amalgamates most wood samples, excepting Aspen tree samples. The second and third parts of the distribution line consist mostly the Aspen tree samples taken from two different... 

If the modification imparts dimensional stability to the wood, the difference between the water-saturated and oven-dry volume of the wood sample is reduced, resulting in a lower value for S. The increase in dimensional stability can then be evaluated in terms of an anti-swelling efficiency (ASE) ... 

Nishino (1991) noted the presence of an induction period in the kinetic profile of reactions of solid wood samples with acetic anhydride vapour. The duration of this induction period decreased and the rate of reaction increased with both increasing temperature and concentration of acetic anhydride vapour in the reaction vessel (Nishino, 1991). The rate of reaction was diffusion limited, with the rate of diffusion being greatest in the longitudinal direction of the wood samples. This phenomenon is only found in solid wood samples, since no induction period was noted for the reaction of wood fibres with acetic anhydride vapour (Loras, 1968). 

The use of microwave energy combined with applied vacuum to remove residual chemicals has been smdied (Larsson Brelid and Simonson, 1999). Larsson Brelid (2002) also smdied me effect of post-reaction treatment upon me final WPG obtained by me wood samples. 

Larsson and Simonson (1994) studied the mechanical properties of acetylated Pinus sylvestris and Picea abies. The MOR and MOE decreased by about 6 % for pine, but increased by about 7 % with spruce samples after acetylation. Samples for this study were vacuum/pressure impregnated with acetic anhydride, excess anhydride was then drained off and samples were heated at 120 °C for 6 hours. The hardness of the acetylated wood samples was also found to increase, which was considered to result from the lower MC of the modified wood. Acetylated samples were also found to be less susceptible to deformation when subjected to varying RH. 

The dynamic viscoelastic properties of acetylated wood have been determined and compared with other wood treatments in a number of studies. Both the specific dynamic Young s modulus (E /j) and tan S are lower in acetylated wood compared with unmodified wood (Akitsu etal., 1991, 1992, 1993a,b Korai and Suzuki, 1995 Chang etal., 2000). Acetylation also reduces mechanosorptive creep deformation of the modified wood (Norimoto etal., 1992 Yano etal, 1993). In a study of the dynamic mechanical properties of acetylated wood under conditions of varying humidity, it was concluded that the rate of diffusion of moisture into the wood samples was not affected by acetylation (Ebrahimzadeh, 1998). 

Suttie etal. (1997, 1998) tested wood samples modified with acetic, propionic or butyric anhydride in EN113 tests, and in vermiculate overlay tests based upon BS 1982. 

Li etal. (2000a, 2001b) smdied the flammability of wood modified with acetic or propionic anhydrides, finding that this parameter, as determined by limiting oxygen index (LOI), was the same as that found for unmodified wood. Samples were also prepared which were impregnated with sodium silicate prior to anhydride modification. The latter treatment resulted in a decrease in flammability, as shown by an increase in the LOI of the wood. 

The efficacy of anhydride modification to provide envelope protection to wood was examined using an ENV839 test against G. trabeum or C. versicolor. Wood samples were... 

The first literature report of a reaction of an isocyanate with wood is that due to Clermont and Bender (1957). In this study, DMF impregnated wood samples 1/8 in thick were suspended above phenylisocyanate liquid in a vessel heated at temperatures from 100 °C to 125 °C for various time intervals. Treated samples were washed with DMF, then water, then acetone, and dried in an oven at 105 °C. ASEs in the range of 60-80 % were reported for these samples. In view of the reactivity of DMF with isocyanates, the lack of an efficient clean-up procedure and the fact that ASE values were calculated from the first water-soak cycle only, this study is of limited value. 

Martins and Banks (1991) modified pine and wood samples with phenyl or butyl isocyanate and investigated the water vapour sorption properties of the modified wood. Modification resulted in a reduction in EMC at a given RH up to about 35 % WPG with butyl isocyanate, although reaction with phenyl isocyanate above 25 % WPG resulted in an increase in sorption due to cell wall damage caused by the reaction. The butyl derivative was more effective at reducing hygroscopicity over all the WPGs studied. 

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