Lattice Conversion of Cellulose in Wood

Abstract

When peracetylated wood, prepared in an acetic anhydride-pyridine medium, was saponified and recrystallized, almost no conversion of cellulose I to cellulose II took place. Neither was conversion detected, when thirteen species of wood, differing in density from 0.17 to 0.71, as well as in lignin content from 18.1 to 38.8 %, were treated with 17.5 % aqueous NaOH, followed by recrystallization. The corresponding treatments for cellulose triacetate or cellulose resulted in complete conversion to cellulose II. Partial delignification of wood preceding the alkali-induced mercerization was found to cause partial lattice conversion to cellulose II, and the ratio of lattice conversion (L.C.R.) increased with the degree of delignification. The L.C.R. value reaches slightly more than 50 %, when one third of the lignin is removed, and the removal of about two third of the lignin from wood results in an almost complete conversion. The effect of lignin removal on lattice conversion was similar among the wood species, irrespective of their density and lignin content, Introduction of acyl groups larger than caproyl into wood, followed by saponification and mercerization resulted in a high conversion of cellulose in wood from cellulose I to cellulose II.