Beech pulp

Table VI. Influence of Drying on Acid and Enzymatic Hydrolysis of Beech Pulp...

Nonwoven mats of cellulose microfibrils were also used to prepare polyurethane composite materials via film stacking method [160], Water-redispersible nanofibrillated cellulose in powder form was recently prepared from refined bleached beech pulp by carboxymethylation and mechanical disintegration [161], However, the carboxymethylated sample displayed a loss of crystallinity and strong decrease in thermal stability limiting its use for nanocomposite processing. 

BWX= beech wood xylan, BPX= beech pulp xylan, CCX= com cob xylan. 

Solvent-extracted delignified beech wood pulp was treated with potassium tertiary butoxide, then with quinone methides at 25 °C or 45 °C (Figure 4.13). Following reaction, extensive solvent extraction was then performed, and the modified flour was pressed to form a disc, which was then exposed to C. versicolor or G. trabeum. No indication of biological attack was found (Loubinoux etal., 1992). 

Our experimental work started from the following original cellulose samples (a) acetate-grade, bleached cotton linters, DP 1800 (b) hot, refined, spruce, sulphite-dissolving pulp, machine dried, ca. 93% a-cellulose, DP — 750 (c) never-dried, normal, rayon-grade, beech sulphite pulp, ca. 90% a-cellulose, DP = 825 (d) commercial cellulose powders obtained by hydrolytic degradation and/or mechanical disintegration of cotton linters or spruce sulphite pulp. 

In agreement with this hypothesis is the remarkable low rate constant with a never-dried beech sulphite dissolving pulp compared with the dried sample at identical conditions of aqueous acid hydrolysis (Table VI). 

Beech sulphite pulp (bleached, chem. grade) 1.8 2.6... 

Fig. 8 Ozone bleaching (Z) of a beech sulfite pulp, increasing numbers reflect increasing intensity of the ozone treatment. Left differential MWD und carbonyl DS. Right ADSco plots showing the differences in carbonyl content between the bleached sample and the starting material (SM). Reprinted with permission from Biomacromolecules (2002) 3 969. Copyright (2002) American Chemical Society...

Fig. 20 Group selective labeling agents for chemical microscopy by TOF-SIMS. Analysis of a CCOA-labeled (right) and an FDAM-labeled beech sulfite pulp...

Fiserova M, Suty L (1980) Comparative studies on milled wood lignins and cellulolytic enzyme lignin of beech wood (Fagus silvatica L ) Cellul Chem Technol 14 243-252 Glasser WG, Barnett CA (1979) The structure of lignins in pulps II A comparative evaluation of isolation methods Holzforschung 33 78-86... 

In preparing compositions use is made of organic and mineral fillers. The most important organic filler is bleached wood pulp. The pulp fiber length depends on the type of wood thus, pulp produced from beech has 1 mm-long fibers, whilst that obtained from conifers -3 mm-long fibers. 

Fukagawa, N., Meshitsuka, G., and Ishizu, A. (1992) 2D NMR study of residual lignin in beech kraft pulp combined with selective cleavage with pivaloyl iodide. J. Wood Chem. Technol. 12(4), 425 45. 

The cellulose mixtures used in filtration are made from wood (pine, birch and beech) subjected to special shredding and chemical breakdown treatments to dissolve the lignin and release the fibers. The raw wood pulp is washed with water and then undergoes several additional stages of purification. The purified pulp is formed into sheets and dried. The fibers are isolated by mechanical treatment and may be broken up into powder. A range of different particle sizes and filtration efficiencies are produced by varying the intensity of the mechanical processing. 

At present, only a few polyoses from wood are chemically used. An example is the utilization of xylose (Figure 9.4.4), which can be obtained as a by-product in the pulping process of beech or birch wood and which is used in the form of the sugar alcohol xylitol as a sugar substitute (E 967) as well as arabinogalactan as a thickening agent (E 414) in the food industry. 

Figure 9.4.4 Example of mass balance of a beech sulphite pulping.

A reaction was performed with plywood sawdust in ethanol at 200°C. This reaction produced a similar yield of ethyl levulinate (23 wt%) and only a little less resin. A comparison of these results with those of Garves (P) shows that similar temperatures are required for the various cellulosic materials. Garves obtained higher wt% yields from beech sulfite pulp (30.6 wt%) and lower yields from waste paper fluff (18.5 wt%) for reactions in methanol. 

Materials. TCF-bleached beech Mg-sulphite dissolving pulp (BS), with 93.8% R18,2.9% pentosan, and 1.7 copper number, and Eucalypt prehydrolysis kraft pulp (EK), with 96.6% R18, 3.6% pentosan and 0.2 copper number, were... 

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