Sulphite lignin properties

Semichemieal pulps produced by the sodium bisulphite and neutral sulphite-anthraquinone pulping processes at 75% yields have properties that are rather similar to a lower yield chemical pulp shown in Table 13.4. The pulp eharaeteristies from this proeess are of considerable interest, since it has been shown that ehemical pulps made by the so-ealled ASAM process, in which the wood is delignified with a liquor containing sodium sulphite, sodium carbonate or sodium hydroxide and methanol (c. 40% of the liquor by volume) with a trace of anthraquinone ean be delignified more rapidly and to a lower kappa number (this surrogate measure of the lignin content of pulp is explained in the appendix) than pulps made in the absenee... 

A similar change of dynamic mechanical properties of wood was observed by mild chemical treatments with chemicals such as sodium sulphite. These chemical treatments enhance the molecular motion of lignin by replacing hydroxyl and ether... 

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

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