Soda lignin applications

The application of C NMR techniques to the characterization of soda lignin confirmed that formaldehyde was released from the y-hydroxymethyl groups of C9 units during pulping via reverse aldol reactions with subsequent formation of vinyl ether structures in the lignin matrix [387]. Furthermore, in the same study, it was confirmed... 

Soda lignins do flow when heated and their glass transition tenperatures have been reported in the range of 158-185°C [71]. The lack of sulphur gives them some advantage over kraft lignins for applications for which thermal flow is a requirement and volatile sulphurous emissions are undesirable. 

The main applications for soda lignins include the following ... 

However, lignin may find application as a suitable wood-composite adhesive in adhesive formulations if chemically modified in some manner. In this respect, the recent developments with soda bagasse lignin-resorcinol-formaldehyde and lignin-isocyanate adhesives allow for some cautious optimism for the future. 

Lignin was obtained from an industrial soda bagasse spent liquor as before (5). The lignin was initially evaluated as a thermosetting adhesive by the beech strip test. Prior to its application as adhesive, the lignin was reacted with formaldehyde in alkali at temperatures below 60 °C to afford a hydroxymethylated lignin (fi). The hydroxymethylation reaction was done at pH 12 and 13, and samples of the reaction mixtures were evaluated on beech strips with overlaps of 25 x 25 mm, cured for 4 hours at 90 °C and 12% equilibrium moisture content. 

Lignin, Industrial production. Sulphite pulping, Kraft pulping. Soda pulping, Lignosulphonates, Properties, Applications, Steam explosion, Organosolv technology... 

Mansouri, N.-E. E., and Salvado, J. (2006]. Structural characterization of technical lignins for the production of adhesives Application to lignosulfonate, kraft, soda-anthraquinone, organosolv and ethanol process lignins. Ind. Crops Prod., 24,8-16. 

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