Cottonwood black

Table IV. Mn of Black Cottonwood Alkali Lignin Fractions in Different Solvents and at Several Temperatures...

Table VI. LALLS Results on Acidic Organosolv Lignin Fractions from Black Cottonwood...

Alkali Lignin. Black cottonwood platelets were cooked in a flow-through reactor with 1.0N NaOH at 160°C flowing at a steady rate of about 17.5 ml.min-1 (3). The effluent was collected as several successive fractions from which lignin was precipitated and purified (3). The same procedure was applied, at 170°C, to spruce matchsticks. 

Organosolv lignin was isolated from black cottonwood (P. trichocarpa) which had been pulped using a methanol/water (70/30) solvent system with NaHSC>4 as a catalyst (28). The chloroform-soluble fraction of this lignin was utilized in this study. lH-nmr broad peaks were observed at 3.7 and 6.7 ppm C-nmr 55.9 (-OCH3), and other typical lignin peaks were observed from 103 ppm to 152 ppm. 

Cole, B.J.W. Black Cottonwood (Populus trichocarpa) Organosolv Pulping and Chemical Composition, M.S. Thesis, University of Washington, Seattle, WA, 1983. 

Table 8.2.2. Weight-average molecular weights of acidic organosolv lignin fractions from black cottonwood determined with a LALLS photometer. (Pla et al. 1986)...

Tables 8.2.2 and 8.2.3 give typical results for two series of polydisperse lignin fractions obtained from acidic organosolv delignification of black cottonwood (Pla et al. 1986) and from alkaline delignification of western hemlock (Dolk et al. 1986). In both cases, LALLS allows accurate determination of low molecular weight values. The nearly identical dn/dc values for a given series of lignin fractions indicate the good reproducibility and accuracy of the technique. However, the second virtal coefficients, A2, vary considerably depending upon the fraction measured.

Pla F, Dolk M, Yan JF, McCarthy JL (1986) Lignin 23 Macromolecular characteristics of alkali lignin and organosolv lignin from black cottonwood Macromolecules 19 1471-1477 Pla F, Froment P, Capitim R, Tistchenko AM, Robert A (1977) Etude d une ligninc d extraction par diffusion de la lumiere avec source laser Cellul Chem Technol 11 711-718... 

Table 8.3.3. Number-average molecular weights of black cottonwood alkali lignins measured at various temperatures (solvent. 2-methoxyethanol) (Pla et al 1986)...

Tuskan GA, Difazio S, Jansson S, Bohlmann J, Grigoriev I, Hellsten U, Putnam N, Ralph S, Rombauts S, Salamov A. et al. The genome of black cottonwood, Populus trichocarpa (Torr. Gray). Science 2006 313 1596-1604. 

The genus Populus includes hardwood trees commonly referred to as poplars, cottonwoods, and aspen, which are found throughout North America, Europe, and northern Asia. They are particularly dominant in the boreal forest and in the parkland zones of Canada and the American midwest. Widespread North American species include P. balsamifera (balsam poplar), with a range from Western Alaska to northern Quebec and Newfoundland, and P. tremuloides (trembling or quaking aspen), which is found from Alaska to Mexico. Both are prominent species of the boreal forest of Canada. P. trichocarpa (black cottonwood) is found along the Pacific coast from California to Alaska. The range of P. tremula (European aspen)... 

Djerbi S., Lindskog M., Arvestad L., Sterky F., and Teeri T.T. 2005. The genome sequence of black cottonwood (Populus trichocarpa) reveals 18 conserved cellulose synthase (CesA) genes. Planta 221 739-746. 

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