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- Improvement on Cellulose Dissolution of Prehydrolyzed-kraft Pulps, their Characterization and Potential for the Lyocell ProcessPublication . Damaceno, Thalita Pedroso; Vaz, Álvaro Frederico Campos; Simões, Rogério Manuel dos SantosThe textile industry introduced the lyocell process following the increasing demand for regenerated cellulose fibers and as an environmentally friendly alternative to the consolidated viscose process. Some pulp properties are required to ensure pulp dissolution and regenerated fiber mechanical strength preservation, such as high ??- cellulose content, a moderate degree of polymerization (DP), and high purity (low metal ion and ash content). This work involved the understanding of the influence of prehydrolysis conditions on the properties of dissolving wood pulp (DWP) from Eucalyptus globulus, and the improvement of cellulose dissolution from the recycled paper pulp (RPP) by optimizations in the kraft cooking process. The E. globulus wood chips submitted to a flow-through (FTR) acid-hydrolysis showed, between other properties, lower hemicellulose content (3.8%) and intrinsic viscosity (549 cm3/g) when compared to a DWP which the auto-hydrolysis occurred in a batch reactor, with 4.9% of hemicelluloses and 874 cm3/g of intrinsic viscosity. These results evidenced the efficiency of acidhydrolysis on hemicellulose removal and its effect on cellulose-chain degradation, seen as a positive outcome, with a greater Fock’s test reactivity (71% for DWP-FTR vs. 57% for DWP-Batch). For the RPP, the optimum performance was obtained with a kraft cooking at 170ºC, H-factor around 2,000, where the treated pulp showed a cellulose and hemicellulose content of 89% and 5%, respectively. This processing resulted in a remarkable increase of 84% in pulp reactivity, and a reduction of 82% in the insoluble matter compared to the untreated pulp (RPP Original). The dissolution extension and time to all studied pulps in solvent systems LiCl/DMAc, and NMMO/H2O were discussed regarding their physicochemical properties. The dissolving pulps produced under this work showed great potential as raw materials for textile applications, with a particular highlight on recycled paper pulp and the innovative process developed to improve its solubility. However, some adjustments are still necessary to increase its purity.