Sökning: "xylan"

Visar resultat 21 - 25 av 90 avhandlingar innehållade ordet xylan.

1. 21. Fast pyrolysis of biomass : primary products and reaction pathways

   Författare :David Usino; Tobias Richards; Weihong Yang; Högskolan i Borås; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fast pyrolysis; Py-GC-MS FID; Primary reactions; Cellulose; Xylan; Lignin; Birch wood; Co-pyrolysis; Mahogany; Iroko; Palm kernel shell; Biomass blend; Biomass interaction; Pretreatment; Resource Recovery; Resursåtervinning;

   Sammanfattning : Pyrolysis of biomass to produce liquid fuel and chemicals has been considered as an alternativeto fossil fuel because biomass has a lower environmental impact; moreover, it is renewable andcould be sustainable. However, the process of bio-oil production involves a series of complexchemical reactions which are dependent on the biomass feedstock and composition,temperature, heating rate as well as residence time. LÄS MER

3. 22. 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 :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; 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

4. 23. On the Course of Kraft Cooking - The impact of ionic strength

   Författare :Binh Dang; Chalmers tekniska högskola; []
   Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; molecular weight distribution.; hexenuronic acids; carbohydrate removal; delignification; sodium ion concentration; lignin; ionic strength; xylan; flow-through kraft cooking; kinetics;

   Sammanfattning : Kraft pulping is the dominant process currently used to produce chemical pulps, and has been applied for more than 130 years. A large number of studies have been conducted to gain a better understanding of the delignification kinetics as well as the reactions of the wood components being dissolved during the cooking process. LÄS MER

5. 24. Foaming of cellulose derivatives and hemicellulose-containing materials

   Författare :Kristina Karlsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; β-glucan; arabinoxylan; scale-up production; hydroxypropyl methylcellulose HPMC ; ethyl hydroxyethyl cellulose EHEC ; hot-mould foaming; extensional viscosity; extrusion; hemicellulose; rheological characterisation; Foaming; xylan; cellulose derivatives;

   Sammanfattning : Fossil-based polymeric foams are important materials due to their good mechanical properties relative their low density, the low price and the possibility for large-scale production. They are widely used in cushioning, absorbing and insulation applications. There are however a few disadvantages with these foamed products. LÄS MER

7. 25. Ultrastructural Aspects of Pulp Fibers as Studied by Dynamic FT-IR Spectroscopy

   Författare :Margaretha Åkerholm; KTH; []
   Nyckelord :cellulose; cooperation; crystallinity; dynamic test; glucomannan; hardwood; holocellulose; humidity; infrared spectroscopy; kraft pulp; lignin; mechanical pulp; orientation; polarised light; softwood; strain; sulphite pulp; viscoelasticity; xylan;

   Sammanfattning : Dynamic (or 2D) FT-IR spectroscopy in combination withpolarized IR irradiation has been used in this work to studywood polymer orientation and interactions on theultrastructural level in wood fibers in the native state aswell as the effects of different pulping processes. The woodpolymer interactions were studied under both dry and humidconditions. LÄS MER