Sökning: "cellulose ethers"

Visar resultat 6 - 10 av 16 avhandlingar innehållade orden cellulose ethers.

1. 6. Bulk and interfacial properties of cellulose ethers

   Författare :Rasmus Bodvik; Per M. Claesson; Orlando J. Rojas; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : This work summarizes several studies that all concern cellulose ethers of the types methylcellulose (MC) hydroxypropylmethylcellulose (HPMC) and ethyl(hydroxyethyl)cellulose (EHEC). They share the feature of negative temperature response, as they are soluble in water at room temperature but phase separate and sometimes form gels at high temperatures. LÄS MER

3. 7. 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. 8. Association Phenomena in Aqueous Solutions of Surfactants and Hydrophobically Modified Polymers

   Författare :Susanne Nilsson; Fysikalisk kemi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; self-diffusion; rheology; cellulose ethers; associating polymers; polymer-surfactant interactions; polymer network; Fysikalisk kemi; Physical chemistry;

   Sammanfattning : Interactions between ionic surfactants (sodium dodecyl sulfate and dodecyltrimethylammonium chloride) and nonionic polymers ((hydroxyethyl)cellulose, ethyl(hydroxyethyl)cellulose and their hydrophobically modified analogous) have been studied by means of rheology, pulsed field gradient nuclear magnetic resonance (PFG NMR), time-resolved fluorescence quenching (TRFQ), dynamic light scattering (DLS) and cryo-transmission electron microscopy (cryo-TEM). In all experiments surfactants have been added in various amounts to polymer solutions at fixed concentrations. LÄS MER

5. 9. Surfactant Responsive Cross-Linked Polymer Hydrogels

   Författare :Jesper Sjöström; Research Policy Institute (RPI); []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physical chemistry; Fysikalisk kemi; Two-step binding isotherms; Resolubilization; Nonmonotonic transient volume changes; Swelling isotherms; Divinyl sulfone DVS ; Polyquaternium; Cellulose ethers; Amphiphilic cross-linked polymers; Responsive gels; Polymer-surfactant interactions;

   Sammanfattning : The focus of the thesis is on chemically cross-linked hydrogels which drastically change their volume when immersed in solutions of different ionic surfactants (with or without added salt). The two main questions addressed are: (1) How useful are simple gel swelling experiments to the study of polymer-surfactant interactions?, and (2) How does the volume of a cross-linked polymer gel change when it is immersed in a surfactant solution, both with respect to the equilibrium swelling and with respect to transient volume changes? Most of the gels studied were prepared by cross-linking linear polymers, which were well studied derivatives of hydroxyethyl cellulose (HEC). LÄS MER

7. 10. Enzyme Hydrolysis of Cellulose Derivatives. Active Site Studies and Polymer Characterisation

   Författare :Herje Schagerlöf; Biokemi och Strukturbiologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Kemi; Chemistry; Humicola insolens; Trichoderma reesei; Bacillus agaradhaerens; Mass spectrometry; Substituent distribution; Characterisation; Endoglucanases; Cellulose derivatives;

   Sammanfattning : Soluble derivatives of cellulose have become increasingly important in industrial products e.g. in pharmaceutical applications and in technical dispersions. The polymer characteristics of modified celluloses are to a high degree determined by the substituent distribution along the polymeric backbone. LÄS MER