HEC hydroxyethyl cellulose

Hydroxyethyl cellulose (HEC), a nonionic thickening agent, is prepared from alkali cellulose and ethylene oxide in the presence of isopropyl alcohol (46). HEC is used in drilling muds, but more commonly in completion fluids where its acid-degradable nature is advantageous. Magnesium oxide stabilizes the viscosity-building action of HEC in salt brines up to 135°C (47). HEC concentrations are ca 0.6—6 kg/m (0.2—21b/bbl). 

Fluid loss additives such as solid particles and water-thickening polymers may be added to the drilling mud to reduce fluid loss from the well bore to the formation. Insoluble and partially soluble fluid loss additives include bentonite and other clays, starch from various sources, crushed walnut hulls, lignite treated with caustic or amines, resins of various types, gilsonite, benzoic acid flakes, and carefully sized particles of calcium borate, sodium borate, and mica. Soluble fluid loss additives include carboxymethyl cellulose (CMC), low molecular weight hydroxyethyl cellulose (HEC), carboxy-methYlhydroxyethyl cellulose (CMHEC), and sodium acrylate. A large number of water-soluble vinyl copolymers and terpolymers have been described as fluid loss additives for drilling and completion fluids in the patent literature. However, relatively few appear to be used in field operations. 

The enzymatic polymerization of lactones could be initiated at the hydroxy group of the polymer, which expanded to enzymatic synthesis of graft copolymers. The polymerization of c-CL using thermophilic lipase as catalyst in the presence of hydroxyethyl cellulose (HEC) film produced HEC-gra/f-poly( -CL) with degree of substitution from 0.10 to 0.32 [102]. 

The presence of anionic or cationic groups at a 0.4 M.S. level inhibited adsorption and interlayer entrapment of 2.0 M.S. hydroxyethyl cellulose(HEC) from fresh water solutions. The lack of adsorption of the cationic HEC is surprising it is related to hydration of the quaternary amine group. Increasing adsorption and interlayer entrapment is observed with both the cationic and anionic HECs with increasing sodium chloride concentration. 

The classic studies of Saunders( 17) demonstrated that in the presence of excess surfactant methyl cellulose (MC) would desorb from monodispersed polystyrene latices. MC is one of the most surface active water-soluble polymers (W-SPs) and it will readily dominate the surface pressure 7T (7T = cre - cr t where cr is the surface tension of water and is the surface tension of the aqueous polymer solution) of the aqueous solution. For example, hydroxyethyl cellulose (HEC) lowers the surface tension of water much less than MC or HPMC, and when the combination of HEC and MC or HPMC in water is studied, there is no notable influence of HEC on the surface pressure (Figure 2). 

Commonly used cellulose derivatives include hydroxypropyl cellulose (HPC), car-boxymethylcellulose, and hydroxyethyl cellulose (HEC). The choice amongst these cellulose derivatives is primarily based on the type of formulation (aqueous or... 

The phase transfer catalyzed alkylation reaction of dodecyl phenyl glycidyl ether (DPGE) with hydroxyethyl cellulose (HEC) was studied as a mechanistic model for the general PTC reaction with cellulose ethers. In this way, the most effective phase transfer catalysts and optimum reaction concentrations could be identified. As a model cellulose ether, CELLOSIZE HEC11 was chosen, and the phase transfer catalysts chosen for evaluation were aqueous solutions of choline hydroxide, tetramethyl-, tetrabutyl-, tetrahexyl-, and benzyltrimethylammonium hydroxides. The molar A/HEC ratio (molar ratio of alkali to HEC) used was 0.50, the diluent to HEC (D/HEC) weight ratio was 7.4, and the reaction diluent was aqueous /-butyl alcohol. Because some of the quaternary ammonium hydroxide charges would be accompanied by large additions of water, the initial water content of the diluent was adjusted so that the final diluent composition would be about 14.4% water in /-butyl alcohol. The results of these experiments are summarized in Table 2. 

CELLOSIZE is Union Carbide s trademark for its hydroxyethyl cellulose (HEC) polymer. 

A third water-soluble substrate for endocellulase is hydroxyethyl-cellulose (HEC). As early as 1931, Ziese (5) used HEC and Sandegren et al. (6) defined the activity as being proportional to the change of the inverse of the specific viscosity per time unit. Child et al. (7) have also used HEC and based their calculation -on a linearization of the viscosity measurements according to Eriksson et al. (8). They defined an enzymic activity unit as the amount of enzyme causing a viscosity change of 0.001 rjre 126 min"1. The exponential factor was used in order to linearize the data. This unit is useful for comparison of cellulases of different origin, but it is based on an empirical relationship. The authors made an evaluation of their method in comparison with CMC hydrolysis. 

Fig. E6.14b Dimensionless plot of squeezing flow data by Leider (50) representing 181 runs for four fluids silicone oil, 1% solution of hydroxyethyl cellulose (HEC), 0.5% solution of Separan (polyacrylamide) in glycerin, and polyisobuthylene solution. [Reprinted by permission from R J. Leider, Squeezing Flow between Parallel Disks, II, Experimental Results, Ind. Eng. Chem. Fundam., 13, 342-346 (1974).]...

Substrates of hydroxyethyl cellulose (HEC) samples of different molar substitution (MS) of oxirane give similar results in grafting with AN as EC (Table IV). At MS-values of 0.40 and 0.60, the water solubility influences the results, especially the grafting efficiency. HEC-samples of low MS (0.25) give the best results in grafting. 

Grafting of dissolving pulp (MDC) and grease-proof pulp (GP) (both are bleached sulfite pulps from spruce) and low-substituted ethyl cellulose (EC) and hydroxyethyl cellulose (HEC), all samples in never-dried state, with acrylonitrile (AN) using Mn +ions, complexed with pyrophosphate ip n inin amr >s... 

Hydroxyethyl cellulose (HEC) was initially used as the sieving medium [23]. The differences in migration of PSS in HEC and PEG were studied [25]. The separation potential of PEG was inferior to that of HEC, and the PSS adsorption at the PEG coating increased with increasing PEG concentration in the buffer. 

Hydroxyethyl cellulose (HEC) Water and GI fluids Similar to MC with clear solutions... 

Cellulose derivatives Chitosans Gelatin Sodium carboxymethylcellulose (NaCMC) Methylcellulose (MC) Hydroxypropyl methylcellulose (HPMC) Hydroxypropyl cellulose (HPC) Hydroxyethyl cellulose (HEC)... 

The viscosity of a dispersion may be increased by adding a water-soluble viscosi-tier. There are several types, for example, hydroxyethyl cellulose (HEC) or acrylic viscosiflers, which are added in the form of an aqueous stock solution. To utilize their viscosifying effects fully, the pH of the formulation must be increased to a certain optimum value, typical for a given viscosifler. 

Typical suspension stabilizers for the production of EPS are water-soluble, surface-active macromolecules, such as poly (vinyl alcohol) (PVA), hydroxyethyl-cellulose (HEC) and polyvinylpyrrolidone (PVP), or natural products, such as gelatin [36-40], and insoluble inorganic powders, such as tricalcium phosphate (TCP), also called picketing stabilizer , mostly in combination with surfactants called extenders [33-35,44], or a combination of these [129]. The differences and specialties of these stabilizing mechanism are described briefly below ... 

Hydroxyethyl cellulose (HEC) Ethoxylated cellulose C 0 CH2CH2OH c 0 C Substituted pyranose chain sequences... 

Fig. 1 Capillary zone electrophoresis of tryptic digests of (3-casein in 100 mm i.d. x 37-cm capillary. (A) BGE 80 mM phosphate buffer, pH 2.0 injection 0.5 p.s.i. for 3 sec applied field strength 110 V/cm. The three major peaks are 1) p7 6.1, fragment P-CN (114-169) 2) p7 6.93, fragment P-CN (49-97) and 3) p7 3.95, fragment P-CN (33-48). Note that the total running time is 70 min. (B) BGE 50 mM isoelectric aspartic acid (pH = p7 = 2.77) added with 0.5% hydroxyethyl cellulose (HEC) (Mn 27,000 Da) and 5% trifluoroethanol applied field strength 600 V/cm. (From Ref. [13].)...

When the hydrogen atom of the hydroxyl group on C6 of cellulose is partially substituted with a hydroxyethyl (-CH CH OH) group in a reaction with ethylene oxide under alkaline condition, hydroxyethyl cellulose (HEC) is produced. So far there are no known testing methods for HEC detection. However, if one wants to distinguish CMC from HEC, an ion tolerance test can be conducted. CMC is anionic and can be precipitated from an aqueous solution with a cationic surfactant. Since HEC is non-ionic, its aqueous solution is compatible with cationic surfactants. Based on the same ionic tolerance principle, a high salt concentration can precipitate CMC, not HEC. 

The use of strongly anchored dispersants and emulsifiers is cmcial for reducing the interaction between the particles and droplets. The interaction can also be significantly reduced by the addition of rheology modifiers such hydroxyethyl cellulose (HEC) or xanthan gum. 

Cellulose ethers, more particularly methyl cellulose (MQ, methylhydroxypro-pyl cellulose (MHPC) and hydroxypropyl cellulose (HPC) are used as protective colloids also called primary suspending agents in suspension polymerization for the manufacturing of S-PVC. Their role is maintaining the particle size of the resin. Hydroxyethyl cellulose (HEC) is preferred for manufacturing of vinyl acetate emulsion polymers and as a thickening agent in dispersimi paints. 

Hydroxyethyl cellulose (HEC) is a water-soluble nonionic polymer having the general structure shown in Figure 5.14 [27], The water solubility of HEC depends upon DS and the molar substitution (MS also termed moles of substitution). 

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