Cellulose hydroxyethyl , dynamic

Dynamic Behavior of Hydrophobically Modified Hydroxyethyl Celluloses at Liquid/Air and Liquid/Liquid Interfaces... 

The rheological properties of a fluid interface may be characterized by four parameters surface shear viscosity and elasticity, and surface dilational viscosity and elasticity. When polymer monolayers are present at such interfaces, viscoelastic behavior has been observed (1,2), but theoretical progress has been slow. The adsorption of amphiphilic polymers at the interface in liquid emulsions stabilizes the particles mainly through osmotic pressure developed upon close approach. This has become known as steric stabilization (3,4.5). In this paper, the dynamic behavior of amphiphilic, hydrophobically modified hydroxyethyl celluloses (HM-HEC), was studied. In previous studies HM-HEC s were found to greatly reduce liquid/liquid interfacial tensions even at very low polymer concentrations, and were extremely effective emulsifiers for organic liquids in water (6). 

Polymers such as polyfvinyl alcohol), dextrans, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and polyfethylene oxide) can be used as dynamic or permanent coatings. The latter mode is generally more effective. 

Viscosity (dynamic) hydroxyethyl cellulose is available in a wide range of viscosity types e.g. Cellosize is manufactured in 11 regular viscosity grades. Hydroxyethyl cellulose grades differ principally in their aqueous solution viscosities which range from 2-20 000 mPas for a 2% w/v aqueous solution. Two types of Cellosize are produced, a WP-type, which is a normal-dissolving material, and a QP-type, which is a rapid-dispersing material. 

Nahringbauer, I. Dynamic surface tension of aqueous polymer solutions, I Ethyl(hydroxyethyl)cellulose (BERMOCOLL cst-103), /. Colloid Interface Sci., 176, 328,1995. 

Thuresson, K., B. Nystroem, G. Wang, and B. Lindman (1995). Effect of surfactant on structural and theimo-dynamic properties of aqueous solutions of hydrophobically modified ethyl (hydroxyethyl) cellulose. Langmuir 11(10) 3730-3736. 

Kjoniksen, A.-L. Nystrom, B. Lindman, B. (1998) Dynamic Viscoelasticity of Gelling and Nongelling Aqueous Mixtures of Ethyl(hydroxyethyl)cellulose and an Ionic Surfactant, Macromolecules, Vol.31(6), 1852-1858. 

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