Sökning: "etherification"

Visar resultat 6 - 9 av 9 avhandlingar innehållade ordet etherification.

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

    Författare :Heléne Almlöf Ambjörnsson; Ulf Germgård; Thomas Nilsson; Storker Moe; Karlstads universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; 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

  3. 7. Extended Mercerization Prior to Carboxymethyl Cellulose Preparation

    Författare :Heléne Almlöf; Ulf Germgård; Björn Kreutz; Monica Ek; Karlstads universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; 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

  4. 8. Synthesis, characterization and applications of hierarchical porous inorganic materials: a multi-dimensional approach

    Författare :Junzhong Lin; Junliang Sun; Xinwen Guo; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Zeolites; Porous material; Hierarchical; Synthesis; Catalysis; MFI zeolite; MWW zeolite; ZSM-5; TS-1; Inorganic Chemistry; oorganisk kemi;

    Sammanfattning : Zeolites are a type of microporous crystalline materials that have been widely used in industrial applications including separation, adsorption, and catalysis. However, great limitations on diffusion through these materials can arise due to the small pores present in mircoporous frameworks, and this can impact catalytic reactions in particular. LÄS MER

  5. 9. Biopolymers and materials from rapeseed straw biorefining

    Författare :Antonia Svärd; Ulrica Edlund; Elisabet Brännvall; Stefan Willför; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Rapeseed canola straw; biorefinery; hemicelluloses; lignin; cellulose; cellulose nanoparticles; films; grafting; thermoplastic; biocomposites; rapshalm; bioraffinaderi; hemicellulosa; lignin; cellulosa; cellulosa nano partiklar; hemicellulosafilm; ympning; termoplastisk; biokompositer; Fiber- och polymervetenskap; Fibre and Polymer Science;

    Sammanfattning : Rapeseed straw was fractionated through a hydrothermal process into its hemicellulose, lignin and cellulose components. In the first step, hemicellulose-rich fractions were extracted. Xylan-rich fractions with high molecular weight, 30,000 – 50,000 g/mol, were obtained at 110 °C and 1.5 M NaOH. LÄS MER