Sökning: "Ulf Germgård"

Visar resultat 1 - 5 av 15 avhandlingar innehållade orden Ulf Germgård.

  1. 1. Mercerization and Enzymatic Pretreatment of Cellulose in Dissolving Pulps

    Författare :Heléne Almlöf Ambjörnsson; Ulf Germgård; Thomas Nilsson; Storker Moe; Karlstads universitet; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; alkali; carboxymethyl cellulose; cellulose I; cellulose II; cellulose dissolution; degree of substitution; enzymatic treatment; filterability; gel formation; mercerization; multivariate analytical methods; NIR FT Raman spectroscopy; sodium hydroxide; zink oxide; Chemical Engineering; Kemiteknik;

    Sammanfattning : This thesis deals with the preparation of chemically and/or enzymatically modified cellulose. This modification can be either irreversible or reversible. Irreversible modification is used to prepare cellulose derivatives as end products, whereas reversible modification is used to enhance solubility in the preparation of regenerated cellulose. LÄS MER

  2. 2. Extended Mercerization Prior to Carboxymethyl Cellulose Preparation

    Författare :Heléne Almlöf; Ulf Germgård; Björn Kreutz; Monica Ek; Karlstads universitet; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; Carboxymethyl cellulose; Mercerization; DS; FT Raman spectroscopy; Filtration ability; Chemical engineering; Kemiteknik; Chemical Engineering; Kemiteknik;

    Sammanfattning : Carboxymethyl cellulose (CMC) is produced commercially in a two-stage process consisting of a mercerization stage, where the pulp is treated with alkali in a water alcohol solution, followed by an etherification stage in which monochloroacetic acid is added to the pulp slurry. In this thesis an extended mercerization stage of a spruce ether pulp was investigated where the parameters studied were the ratio of cellulose I and II, concentration of alkali, temperature and retention time. LÄS MER

  3. 3. New methods for evaluation of tissue creping and the importance of coating, paper and adhesion

    Författare :Jonna Boudreau; Christophe Barbier; Ulf Germgård; Sverker Albertsson; Robert Pelton; Karlstads universitet; []
    Nyckelord :tissue; creping; paper adhesion; Tissue paper; creping; paper adhesion; coating layer; adhesives; Yankee cylinder; crepe structure; wavelength measurements; Chemical Engineering; Kemiteknik;

    Sammanfattning : The creping process and the conditions on the Yankee cylinder dryer are key factors in a tissue paper mill, and they therefore need to be kept under good control in order to maintain a high and uniform quality. To this end it would be valuable to be able to make on-line measurements of Yankee coating thickness as well as the crepe structure of the tissue paper. LÄS MER

  4. 4. The initial phase of sodium sulfite pulping of softwood : A comparison of different pulping options

    Författare :Raghu Deshpande; Ulf Germgård; Pedro Fardim; Karlstads universitet; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; Activation energy; acid sulfite pulping; bisulfite pulping; cellulose; delignification; dissolving pulp; extractives; glucomannan; hemicelluloses; lignin; lignin condensation; lignin carbohydrate complexes; pine; spruce; thiosulfate; total SO2; xylan; Chemical Engineering; Kemiteknik;

    Sammanfattning : Single stage and two-stage sodium sulfite cooking were carried out on either spruce, pine or pure pine heartwood chips to investigate the influence of several process parameters on the initial phase of such a cook down to about 60 % pulp yield. The cooking experiments were carried out in the laboratory with either a lab-prepared or a mill-prepared cooking acid and the temperature and time were varied. LÄS MER

  5. 5. The initial phase of the sodium bisulfite pulping of softwood dissolving pulp

    Författare :Raghu Deshpande; Ulf Germgård; Martin Ragnar; Karlstads universitet; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Activation energy; bisulfite pulping; cellulose; delignification; extractives; glucomannan; hemicelluloses; lignin; pine; spruce; thiosulfate; total SO2; xylan; Chemical Engineering; Kemiteknik;

    Sammanfattning : The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. LÄS MER