Viscosity cellulose ether table

Extent of solvation and intrinsic viscosity are interconnected. Highly disentangled and expanded chains result in high values of conformational exponent, a, of the Mark-Houwink equation. Few literature data are available for water-soluble cellulose ethers (Table 5). 

TABLE 8 Specification Limits for Viscosity of Cellulose Ether... 

Cellulose ethers swell or are colloidally soluble. They all raise viscosity and have specific rheology profiles (seeO Fig. 18). Many cellulose ethers are surface-active, and they reduce the surface activity of water by about 20 to 25% depending on type. Cellulose ethers are generally compatible with other hydrocolloids and many other substances. The field has recently been reviewed by Majewicz et al. [95]. The primary manufacturers of industrial cellulose ethers are listed in O Table 14. 

Surface tensions of 2% aqueous solutions of commercially used water-soluble cellulose ethers were determined for comparative purposes in the author s laboratory (Table 10). Five derivatives were selected, each with two different molecular weights (nominal viscosity grades). 

TABLE 10.2 Viscosity of Typical Cellulose Ethers, 2% Solution in Water (Manufacturers Data) ... 

This PE is described in the USP as the sodium salt of polycarboxymethyl ether of cellulose. Its typical molecular weight is 90.000-700.000. The rheological properties of CMC depend on the polymer concentration and on the degree of substitution (conversion of -OH into -0-CH2-COO ) which varies from 0.5 to 1.2 [35, 36]. Thus, various grades of CMC with different aqueous viscosities are available, currently regarded as low-, medium-, and high-viscosity (CMC-Na (LV), CMC-Na (MV) and CMC-Na (HV), respectively). At 1 % w/v aqueous concentration they yield the viscosities described in Table 2 [10]. 

Cellulose esters and ethers of various types and viscosities are characterized by their degree of substitution (DS), i.e. the average number of substituted hydroxyl groups (the maximum value is 3, see also Table 3). Furthermore, ethers or ether esters with hydroxyalkyl groups attached are characterized by the degree of reaction (DR), also frequently named molar substitution (MS), i.e. the average number of molecules of reagent (alkylene oxide) reacted with each... 

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