Ethyl hydroxy cellulose

O Rosen, L Picullel. Interactions between covalently crosslinked ethyl(hydroxy-ethyl)cellulose and SDS. Polym Gels Networks 5 185-200, 1997. 

LMC is used in underwater concrete for both new construction and repair. The important requirements to obtain antiwashout capability, such as segregation resistance, flowability, self-leveling characteristics and lower bleeding are provided by the addition of viscosity-enhancing polymeric admixtures at polymer-cement ratios of 0.2-2.0%. These admixtures are water-soluble polymers, and classified under two groups, viz., cellulose types such as methyl cellulose and hydroxy ethyl cellulose and polyacrylamide types such as polyacrylamide and polyacrylamide-sodium acrylate [101]. 

According to the 1981-83 National Occupational Exposure Survey, as many as 15 600 workers in the United States were potentially exposed to di(2-ethylhexyl) adipate (NOES, 1999). Occupational exposure may occur through inhalation, mainly as an aerosol, during its manufacture and its use, particularly as a plasticizer of PVC films and in other materials used in food packaging such as adhesives, cellophane and hydroxy ethyl cellulose films. Exposure may also occur during the manufacture of rubber products, nonferrous wire, cosmetics, lubricants and hydraulic fluids (Opresko, 1984). No measurements of di(2-ethylhexyl) adipate exposure in manufacturing and processing industries are available. 

Then, with a moderate stirring speed, add 4.00 g of Cellosize hydroxy-ethyl cellulose WP-300 (a protective colloid), 2.00 g of Tergitol NP-40, 2.60 g of Tergitol NP-15 (two nonionic surfactants), 2.20 g of Alcolac Siponate DS-4 (an anionic surfactant), an 0.40 g of ammonium bicarbonate. 

Figure 18. Viscosity vs. volume fraction for polystyrene latices in the presence of an adsorbed layer of ethyl hydroxy ethyl cellulose (full coverage) (-O-) particle diameter = 58 nm (-Jk ) particle diameter = 224 nm. Measurements made at pH 9 in 10 3 mol dm 3 sodium chloride solution at 25°C.

Figure 19. Shearing stress vs. rate of shear for a 1.95% solution of ethyl hydroxy ethyl cellulose in 10 3 mol dm 3 sodium chloride at pH 9 and 25°C ( A ) zero time data increasing rate of shear (-Q-) infinite time data decreasing rate of shear.

If the drug is insoluble in water, suspensions have to be administered. In such cases vehicles like sesame oil, hydroxy-methyl-cellulose or hydroxy-ethyl-cellulose can be used. The selection of the vehicle is a critical issue because of inherent toxicity of the vehicle used frequently for kinetic and metabolism studies (e.g. vehicles which form metabolically oxalic acid). Natural oils such as sesame or com oil can be used. However, it should be checked whether the use of oily vehicles alters the gastrointestinal absorption due to their laxative properties and whether oily vehicles can cause oil granulomas (reaction to oily vehicles in the reticulo-endothelial system) in case of parenteral administration. 

Book 7.9 MD 2.8 CD acrylic/ethyl hydroxy ethyl cellulose 3-5%... 

The increase in gel strength with increase in bentonite concentration above the gel point is consistent with the increase in yield value and modulus. On the other hand, the limited creep measurements carried out on the present suspension showed a high residual viscosity Oq of the order of 9000 Nm s when the bentonite concentration was 45g dm. As recently pointed out by Buscall et al (27) the settling rate in concentrated suspensions depends on 0. With a model system of polystyrene latex (of radius 1.55 vim and density 1.05 g cm ) which was thickened with ethyl hydroxy ethyl cellulose, a zero shear viscosity of lONm was considered to be sufficient to reduce settling of the suspension with = 0.05. The present pesticide system thickened with bentonite gave values that are fairly high and therefore no settling was observed. 

The specific limits for the corresponding application can be found on the BfR website [115] MC = Methyl cellulose CMC = Carboxy methyl cellulose HEC = Hydroxy ethyl cellulose HEMC = Hydroxy ethyl methyl cellulose ... 

Hydroxy ethyl cellulose requires long hydration times prior to dispersion. The formation of the gel is the critical step in... 

In conclusion, these studies show that if Colloid and xanthan gum are prepared in an orifice blender, the solutions can be filtered through filters as fine as 0.45 yM without a substantial loss of polymer. On the other hand, polyacrylamide and hydroxy ethyl cellulose solutions lose an appreciable part of their viscosity upon a similar filtration as indicated above. 

All the polymers that have been suggested as mobility control agents are pseudoplastic, i.e., they are shear-thinning. The extent of pseudo-plasticity is different for polyacrylamides, polysaccharides, and hydroxy ethyl cellulose. Viscosities of these polymers are plotted against shear rate in Figure 12. One model that describes the shear-thinning behavior observed is the Ost-wald-de Waele relationship ... 

Hydroxy ethyl cellulose shows a Newtonian-like behavior as shown in Figure 12. This is the case for all the concentrations of Natrosol investigated. The index [1-n] which indicates the deviation from Newtonian behavior is around 0.1 for Natrosol y. 

Mechanical degradation of hydroxy ethyl cellulose is illustrated in Figure 19. Again 100 psi pressure drop leads to some degradation however, 500 psi pressure drop across the orifice decreases the molecular weight by more than a factor of 2. 

For pressures under 300 psi, hydroxy ethyl cellulose seems to be the most resistant polymer (see Figure 20). Since hydroxy ethyl cellulose has the lowest intrinsic viscosity and size in solution, this result should have been anticipated. It should be noted that the Natrosol concentration used is higher than the concentration of the other polymers. The polymer concentration may have a major effect on the mechanical degradation. 

Hydroxy ethyl cellulose undergoes a severe biodegradation if ... 

In this paper the solution properties of a spectrum of mobility control polymers have been compared. Polysaccharides, polyacrylamides, and hydroxy ethyl cellulose show vastly different solution behavior. Despite this, the properties investigated can be correlated by noting one molecular characteristic of these polymers, namely molecular size. 

Pusher -700 and xanthan gum have larger molecular sizes in solution than Colloid and hydroxy ethyl cellulose. The dimensions in solution decrease with increasing salt concentration. Polyacrylamides are affected most severely by the presence of electrolytes. Polysaccharides are also affected by salt, but not to the same extent as polyacrylamides. Hydroxy ethyl cellulose is the most insensitive polymer to salt. Temprature can be inversely correlated with viscosity. Polyacrylamides have low activation energies for viscous flow. In order of decreasing temperature dependency are xanthan gum, Colloid , and hydroxy ethyl cellulose. 

Polyacrylamides are extremely vulnerable to severe shearing while xanthan gum, Colloid , and hydroxy ethyl cellulose are affected to a lesser degree. 

Polyacrylamides are extremely non-Newtonian particularly at low salt conditions, while polysaccharides and hydroxy ethyl cellulose show less pseudoplasticity. The non-Newtonian behavior of all of these solutions can be described by a power law model. Many variables such as salt concentration and polymer concentration influence the extent of pseudoplasticity. 

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