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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Rheological study of cellulose dissolved in aqueous ZnCl2 : Regenerated cellulosic fibres for textile applications / Reologisk undersökning av cellulosa upplöst i vattenhaltig ZnCl2 : Regenererad cellulosa för textilapplikationer

Ulfstad, Louise January 2013 (has links)
The most known regenerated cellulosic fiber is viscose, produced in a wet spinning process, but due to cost and environmental issues other processes have been developed. Lyocell fibers, produced in air-gap spinning, have superior dry and wet strenght and a lower environmental impact compared to viscose. Research in different cellulose solvent has increased significantly tha last decadess, due to an increased cotton price and a decreased paper production, providing more wood pulp to production of regenerated cellulosic fibers.   Inorganic molten salt hydrates have the ability of dissolving cellulose for production of textile fibers. Aqueous zinc chloride was investigated at Swerea IVF from dissolution of cellulose to fiber spinning.   Aqueous zinc chloride has a dissolving capacity of up to at least 13.5 % cellulose, possibly much higher. Dissolving concentration ZnCl2/water range from 65-76 % amd lowest possible ZnCl2 concentration increases as the cellulose concentration increases. Above around 68 % ZnCl2 results in a significantly increased viscosity due to a polymeric structure formed by zinc chloride, creating a network of cellulose-zinc complexes and causing a gel behaviour of the dope difficult to use in spinning processes. The dissolving capacity of 68 % ZnCl2 is only about 8 % cellulose, which is very low compared to other solvents used today e.g. Lyocell and ILs.   Additions of 0.3 % CaCl2 or 0.05-0.1 % NaOH is used to decrease degradation of cellulose. The addition causes ans increased viscosity, which is either a result of less degradation of the interaction of the added molecules to zinc-cellulose complexes. Addition of NaOH results in a temperature dependent geleation at increased temperatures (75˚C and 80˚C), which also might be an effect of the interaction.   Highest tensile strenght was reached for wet spun fibers coagulated in ethanol of 9.5 % cellulose with 0.1 % NaOH addition, with a tenacity of 13-15 cN/tex, elongation of 10-12 % and wet strenght 30 % of dry strenght. Beacuse of many disadvantages of zinc chloride as a solvent, e.g. degradation of cellulose, corrosivity and the viscosity and gel behaviour at cellulose concentrations of 9.5 % and 13.5 % cellulose, a future possibility of a conventional production of textile fibers appears to be quite limited.
92

The permeability of compressed fiber mats and the effects of surface area reduction and fiber geometry

Chen, Fung-Jou 01 January 1975 (has links)
No description available.
93

A study of the relationship between the dielectric constant and accessibility of cellulose

Kane, Daniel E. 01 January 1953 (has links)
No description available.
94

The action of ultraviolet light on cellulose.

Stillings, Robert Almon 01 January 1941 (has links)
No description available.
95

The substituent group distribution in a Michael reaction: carbamoethyl cellulose.

Touzinsky, Gerald F. (Gerald Francis) 01 January 1964 (has links)
No description available.
96

Effects of physical structure on the alkaline degradation of hydrocellulose

Gentile, Victor M. 01 January 1986 (has links)
No description available.
97

A study of the relationship between the di-electric constant and crystallinity of cellulose.

Verseput, Herman Ward 01 January 1951 (has links)
No description available.
98

The limited oxidation of cellulose with nitrogen dioxide in carbon tetrachloride

Parkinson, John Raymond 01 January 1957 (has links)
No description available.
99

The synthesis and characterization of a polymer-supported cellulose model

Bovee, Matthew J. 01 January 1987 (has links)
No description available.
100

An investigation of the haze in cellulose acetates made from wood pulps

Bradway, Keith Emerson 01 January 1953 (has links)
No description available.

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