Aspen wood

Waferboard is made almost exclusively from aspen wood and the flakes are roughly square in shape, up to 2 in. (5 cm) on a side. They are used for low end stmctural sheathing appHcations. 

Espen-holzschliff, m. aspen wood pulp, -stoff, m. Paper) aspen pulp, essbar, a. edible. 

During the past decade, MALDI-TOF MS has proven to be an effective tool for the analysis of oligo- and polymeric mannoglucans (for extensive reviews see [222,223]). SEC/MALDI mass spectrometry was employed in the analysis of hemicelluloses isolated by microwave heat-fractionation from spruce and aspen wood [94]. These methods allowed the separation and characterization of the oligo- and polysaccharide fractions derived from the xylan and mannan components of both woods [224]. 

Efanov, M.V. (2001). Transformations of aspen wood and its principal components by o-acylation. Chemistry of Natural Compounds, 37(5), 482-485. 

Feist, W.C., Rowell, R.M. and Ellis, W.D. (1991a). Moisture sorption and accelerated weathering of acetylated and methacrylated aspen. Wood and Fiber Science, 23(1), 128-136. 

Rowell, R.M., Tillman, A.-M. and Simonson, R. (1986d). Vapor phase acetylation of southern pine, Douglas-fir, and aspen wood flakes. Journal of Wood Chemistry and Technology, 6(3), 449 71. 

Aspen Wood Treated with Chemical-Thermomechanical Process. Aspen wood was pulverized into "chemithermomechanical pulp (CTMP) by a chemical-thermomechanical process 24), During this process, very little hemicellulose and lignin are removed. The CTMP was used without any... 

Table II. Cellulase Production on Aspen Wood with Trichoderma reesd QMY-1...

As a result of these various pretreatments, the hydrolysis experiments were carried out on three different starting materials autohydrolysed aspen wood made either in batch or in continuous equipment and the cellulosic residue of the autohydro-lysis-caustic extraction process. 

Figure 2. Enzymatic hydrolysis of autohydrolyzed aspen wood (continuous autohydrolysis)...

Figure 4. Enzymatic hydrolysis of autohydrolyzed aspen wood (continuous auto-hydrolysis), 10.0% cellulase on wood, pH 4.8,50°C, single and multi-stage...

The data above enable us to make some rough estimates of costs associated with two processes (i) ACID, that is aspen wood-autohydrolysis-caustic extraction-acid hydrolysis-fermentation-distillation and (ii) ENZYME, that is aspen wood-autohydrolysis-caustic extraction-enzymatic hydrolysis-fermentation-distillation. For purposes of comparison, the product in both cases will be assumed to be 10 million gallons of 95% ethanol per year, a minimum economic size. 

Yields of ethanol from aspen wood are 70.7% and 83.4% of theoretical where acid hydrolysis and enzymatic hydrolysis were employed. These were, respectively, 58.4 gallons and 68.9 gallons of 95% ethanol per ton of aspen wood. In addition 426 lb lignin with heat of combustion of 11,100 BTU/lb were obtained. 

Lignin Samples. Ball-milled (BM) aspen lignin was prepared following the procedure of Lundquist et al. (21). The yield of purified milled wood lignin obtained was usually about 10% w/w that of ethanol/benzene-extracted aspen wood. 

Alkaline-extracted/acid hydrolysis (AH/NaOH) lignin samples were prepared by subjecting aspen wood flour to a one hour cook at 120°C in 0.05N sulfuric acid (22), followed by mixing the clarified supernatant with 1% w/w NaOH at 25°C with a Waring blender. The insoluble lignins were precipitated by addition of acid and water washes (32% yield). 

The organosolv (OS) lignin was prepared from the liquor obtained by treating aspen wood flour with a 70 30 MeOHrwater (v/v) extraction at 165°C for 2.5 hours in a rocking autoclave as described in ref. 23. 

Universal Calibration. The aspen wood lignin samples chosen for this study were prepared by organosolv, steam explosion, dilute acid hydrolysis, and ball-milling procedures. 

CA 38, 1637(1944)(Nitration of cellulose in mixts of HNOs O contg materials, such as ether or dichlorodiethyl ether) 139)C.Kullgren, SvenskKemTid 53, 233 41(1941) 56, 221-38 (I944)(ln Ger) CA 36., 262(1942) 40, 2630 (1946XStabilization of NC and comparison of solubilities of NC prepd from wood pulp from cotton) 140)H.A.Aaronson, PATR 1066(1941) (Nitration of high alpha cellulose wood pulp from aspen wood by the Forest Products Lab process) 141)J.M.Williams, OSRD Rpt 898... 

Table III shows the results of such a study. The variation in the nature of the lignin degradation products with initial pH follows the same general pattern as observed using aspen wood—i.e., an increased percentage of the phenylpropane over the phenylpropanol derivative in acid medium and the almost sole production of phenylethane products under alkaline conditions. The total yield of identified products, based on original Klason lignin, is significantly less than that for aspen (Table I).

Jurasek, L. Enzymic Hydrolysis of Pretreated Aspen Wood, In Devel-... 

Despite indications (from analytical data) that a monomethyl ether of a uronic acid occurs in the hydrolyzates of several polysaccharides, definite evidence for the presence of 4-O-methyl-D-glucuronic acid did not appear until 1948, when White found it in mesquite-gum hydroly-zate.14 Confirmation of its presence therein has since13 appeared, and it has also been found in the hydrolyzates from gum myrrh,6 aspen wood,14 and Eucalyptus regnans wood.16... 

D-Xylose-(2 —> 1) 4-O-methyl-D-glucosiduronic acid Aspen wood A a 67 See 70d, 70e... 

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