Sökning: "bleached pulps"

Visar resultat 1 - 5 av 23 avhandlingar innehållade orden bleached pulps.

1. 1. On the importance of oxidizable structures in bleached kraft pulps

   Författare :Olena Sevastyanova; Göran Gellerstedt; Colodette Jorge; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; bleached pulps; betula; eucalyptus; 5-formyl-2furancarboxylic acid; 2-furancarboxylic acid; hexenuronic acid; kappa number; kraft pulps; oxidation equivalents; Cellulose and paper engineering; Cellulosa- och pappersteknik;

   Sammanfattning : After cooking, kraft pulps always contain not only residual lignin but also significant amounts of hexenuronic acid and other non-lignin structures oxidizable by permanganate under the standard kappa number determination conditions. These here referred to as false lignin. LÄS MER

3. 2. Light-Induced Yellowing of High-Yield Pulps. The Effect of Acetylation

   Författare :Magnus Paulsson; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; yellowing; mechanical properties; hydroxyl groups; phenolic groups; paper; high-yield pulps; chromophores; model compounds; acetylation; inhibition;

   Sammanfattning : This thesis is a contribution to the understanding of the mechanism of photoyellowing of high-yield pulps. It also gives some general information about the reactivity of different functional groups in lignin towards acetic anhydride. LÄS MER

4. 3. Surface modification of cellulose materials : from wood pulps to artificial blood vessels

   Författare :Lage Ahrenstedt; Harry Brumer; Lars Wågberg; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biochemistry; Biokemi;

   Sammanfattning : This thesis describes the improvement of two radically different cellulose materials, paper and artificial blood vessels, constructed from two diverse cellulose sources, wood pulp and Acetobacter xylinum. The improvement of both materials was possible due to the natural affinity of the hemicellulose xyloglucan for cellulose. LÄS MER

5. 4. Storage of Hydrogen Peroxide Bleached Mechanical Pulp : Reduction in Reflectance over the Visible Spectrum

   Författare :Sofia Enberg; Per Engstrand; Magnus Paulsson; Mats Rundlöf; Patrik Axelsson; Øyvind Eriksen; Yonghao Ni; Mittuniversitetet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : The objective of this thesis is to determine possible causes of the darkening of hydrogen peroxide bleached mechanical pulp over the visible spectrum and their relative contributions. It focuses on both process conditions and the composition of the pulp and the dilution water, including additions or losses of material along the process line from the bleach tower to the paper machine. LÄS MER

7. 5. Preparation and Characterization of Chemical Pulps from Wood and Reed Canary Grass

   Författare :Helena Håkansson; Karlstads universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; pulping; wood; reed canary grass; acid hydrolysis; microcrystalline cellulose; Chemical Engineering; Kemiteknik;

   Sammanfattning : This thesis presents laboratory results from ethanol pulping of reed canary grass for the production of paper pulp. The focus was on the influence of cooking pa-rameters on the delignification. The strength of the grass pulps was found to be low and the use of such pulps will therefore be limited to a few products. LÄS MER