Lignosulfonates structure

Figure 14.1 A schematic figure illustrating a possible lignosulfonate structure. The longest chain iragrrtent constitutes a lignosulfonate backbone and shorter chains are grafted to this backbone (a). According to Vainio et al. 151, the shape of a lignosulfonate molecule can be approximated by an ellipsoid (b), as shown to the right. The two representations are not to scale.

More recently, Brauns and Seiler (12), (13) extracted native lignin from spruce wood and then homogenized the wood in a colloidal mill. A suspension of approximately one gram of colloidal wood per liter of water was obtained. After the colloidal wood was changed to a solid form, it was found that its cell structure was completely destroyed. However, extraction of this wood with ethyl alcohol at room temperature did not yield further quantities of native lignin. These investigators have also reported the isolation of a lignosulfonic acid-carbohydrate compound. 

The fractions in the region 700-1230 mL in Figure 1 were combined in order to study the structure of the polymeric portion of the birch lignosulfonates. The combined solution was then refractionated by preparative RPC into five fractions (Fig. 2). 

We have doped sulfur lignin and sodium lignosulfonate in vapor-phase (iodine, bromine, and ammonia) and in liquid phase (sodium and ferrichlo-ride). The conductivity mainly depends on the nature of the dopant ion and the doping degree. Doping can be monitored by IR-spectroscopy. The intensities of the peaks decrease, and the fine structure vanishes, when the... 

When sodium lignosulfonate or sulfur lignin are compounded, for instance, with iodine or bromine, complexes supposedly form (16-17). These systems are conductors with mixed ionic and electronic nature. Presumably they are charge transfer complexes, since the electronic conductivity predominates (18-19). These compounded materials form charge transfer structures (20). Water is supposed to introduce ionic conductivity to the system. Impurities affect conductivity, too (21). In any case, the main models of conductivity are probably based on the band model and/or the hopping model. 

Some results of the modification of lignin sulfonate Ultra B002 by reaction with terephthaloyl chloride are summarized in Table VI. The total hydroxyl content of the lignosulfonates as well as their derivatives are presented in Table VII. The hydrolytic resistance of selected products is evaluated in Table VIII. The results presented in Tables VI-VIII stress several advantages of the derivatives with terephthaloyl chloride. The modified lignin sulfonates were insoluble, or only very slightly soluble, in organic solvents. They were, however, soluble in dimethyl sulfoxide. Ordered structures were identified by X-ray studies (16,17). 

Ivancic and Rydholm 14) noted changes in lignosulfonate from a Mitscherlich cook upon various types of treatments by recording ultraviolet and visible spectra. Hydrochloric acid condensation of the lignosulfonate resulted in increased absorption throughout both spectra, and absorption increased with increased reaction time. Thus, the increase in color is reflected by structural changes recorded in the ultraviolet region. 

Lignosulfonate admixtures can be used to produce concrete of a required workability and strength characteristic at lower cement contents than the comparative plain concrete with no adverse effect on the durability of the concrete or total structure. The only exception to this rule would be in conditions where high-sulfate ground waters may be involved when the minimum cement contents of relevant codes of practice should be observed. 

Yean WO, Goring DAI (1965) The molecular weight of lignosulfonates from morphologically different subdivisions of wood structure. Sven Papperstidn 68 787- 790 Yoshihara K, Kobayashi T, Fujii T, Akamatsu I (1984) A novel modification of Klason lignin quantitative method. J Jpn Tappi 38(4) 86-95... 

Second derivative ultraviolet spectroscopy is a simple yet powerful technique for highlighting the fine structure of spectral curves. It involves calculating the second derivative of a spectrum with respect to wavelength and plotting the derivative rather than the spectrum itself. Second derivative absorbance spectra of lignin model compounds, milled wood lignins and lignosulfonates have been published (Lin 1982). 

Occurrence, formation, structure and reactions. Wiley-Interscience, New York,. 597-637 Gummerus M (1985) Sulphite treatment of TMP rejects. Part 1. Properties of fibre fractions at various freeness levels and their influence on the reject pulp. Pap Puu 11 635-647 Heitner C, Hattula T (1988) Ultra-high-yield pulping. Part VI The effect of sulphonation on the development of fibre properties. J Pulp Pap Sci 14 J6-J11 James AN, Tice PA (1965) The presence of carboxyl groups in lignosulfonate preparations. Tappi 48 239-244... 

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