Browsing by Author "Lindberg, Andreas"

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  • Effect of acid hydrolysis on kraft pulp
    (2012) Lindberg, Andreas
     School of Chemical Engineering | Master's thesis
    Wood is primarily pulped to be used as the fundamental raw material for the production of various paper and paperboard products. Pulps made by the prehydrolysis kraft and acid sulphite processes which are utilized for the manufacturing of viscose fibers, cellulose ester and cellulose ether products are called dissolving pulps. These specialty chemical pulps, which have very high cellulose content, are presently experiencing a rise in their global demand due to many factors including an increased demand of viscose textile fibers in China and in other Asian countries. The primary objective of this work was to study the suitability of conventional kraft pulps, which were subjected to a post-cooking hydrolysis stage, as dissolving pulps. This was examined by determining the effect of acid hydrolysis on oxygen delignified hardwood and softwood pulps. The effects of the following acid hydrolysis conditions were investigated: reaction temperature (140 °C, 150 °C and 170 °C), reaction time (30 min, 60 min and 120 min) and initial reaction pH (3.5, 2 and 1.6). Additionally the effect of an alkaline extraction stage (100 °C and 60 min) with two different NaOH dosages (4 % and 8 %) on the hydrolysed pulps was investigated. Acid hydrolysis had a definite effect on the wood carbohydrates, although hemicelluloses were removed only to a certain degree. As the hydrolysis temperature and time were increased and/or the reaction pH was set more acidic the pulps were severely chemically degraded. The alkaline extraction treatment extended the degradation of wood carbohydrates of hydrolysed pulps even o further. Acid hydrolysis and alkaline extraction treatments also decreased the lignin contents of both pulps, evidenced by reductions in pulp kappa numbers. The alkali resistance measurement of treated pulps did not fully correspond to the carbohydrate composition analysis, which complicated the further analysis of the treated pulps.
  • Puumuovikomposiitit ja niiden käyttö teollisuudessa
    (2016-12-11) Markkula, Sami
     Kemiantekniikan korkeakoulu | Bachelor's thesis
  • Selluloosajohdannaisten bioyhteensopivat sovellukset
    (2016-12-05) Halttunen, Jussi
     Kemiantekniikan korkeakoulu | Bachelor's thesis