Cellulose dissolution in aqueous NaOH–ZnO: effect of pulp pretreatment at macro and molecular levels

Abstract This paper discusses the effect of hydrolytic pretreatments on pulp dissolution in aqueous NaOH–ZnO solvent system. Eight samples were studied. They consisted a never-dried softwood kraft that was hydrolyzed under seven different conditions as well without hydrolysis reference. The pulps evaluated both at macro level molecular based their reactivity with 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxo-piperidium (4-AcNH-TEMPO + ). fiber properties (i.e. extent fibrillation, amount fines and width, coarseness, length) chemical composition (hemicellulose cellulose contents) viscosity investigated. results show medium consistency (10%) successful increasing solubility cellulose. Hydrolysis high (50%), other hand, increased only to some extent. With extended treatment time fibers formed aggregates became poor. phenomenon could be overcome by mechanically refining after hydrolysis. Moreover, comparison over degree oxidation revealed needed decrease below ca. 400 ml/g order for outer layers dissolve. Finally, when similar viscosities where compared against each other, ones higher glucomannan contents gels time. true also lowest highest studied samples.