Grades and Types
To serve its diverse markets, Aqualon produces CMC in several grades and in a wide variety of types, based on the degree of substitution, viscosity, particle size, and other parameters.
Grades
Aqualon CMC is available in the three grades outlined below.
Grade Designation Intended Use
Food
F
P*
Food, cosmetic, pharmaceutical
Pharmaceutical PH** Cosmetic, pharmaceutical
Standard None Industrial
*P (1.2 D.S. types and CMC 7L2P)
**PH (0.7 and 0.9 D.S. types)

Degree of Substitution
Aqualon CMC is produced with the following degrees of substitution:
Type Substitution Range (a) Sodium Content, %
7 0.65-0.90(b) 7.0-8.9
9 0.80-0.95 8.1-9.2
12 1.15-1.45 10.5-12.0
(a)Ranges shown in this table are not necessarily current specifications.
(b)ln 7S types, the upper limit of substitution is 0.95.

Higher degrees of substitution give improved compatibility with other soluble components such as salts and nonsolvents. Generally, the number given in the product designation is approximately 10 times the DS.

Table II — Some Types of Aqualon CMC
Viscosity Range at 25°C, (c) cps (mPas) Designations for Indicated Substitution Types
7 9 12
High—at 1% Concentration
2,500-6,000
1,000-2,800
1,500-3,000

7H4
7H3S, 7HOF
7H


9H4
 
Medium—at 2% Concentration
800-3,100
1,500-3,100
400-800
200-800
100-200



7M
7M8S
7M2


9M31
9M8

12M31

12M8
Low (d) —at 2% Concentration
25-50
7L    
—at 4% Concentration
50-200

7L2
   
(c)Ranges shown in this table are not necessarily current specifications.
(d)Some even lower viscosity types are available. Contact your technical representative for additional information.

Viscosity
CMC is manufactured in a wide range of viscosities. High-viscosity types are prepared from high viscosity cotton linters. Medium-viscosity types are prepared from wood pulp of specified viscosity. Low-viscosity types are prepared by aging the shredded alkali cellulose and by using chemical oxidants. The foregoing methods of regulating the viscosity are based on controlling the DP. It is also possible to attain high viscosity by decreasing the solubility so that the product is highly swollen but not completely dispersed. This can be accomplished by decreasing the uniformity of the reaction and lowering the DS. For example, products at DS 1.2 do not have solution viscosities as high as products of DS 0.7 prepared in substantially the same way. However, the solutions of the higher-substituted products are much smoother.

The viscosity ranges of some types are listed in Table II. Others are available to meet specific needs. Regular viscosity types with a DS of 0.7 meet most needs and are designated by the number 7, followed by the letter H (high), M (medium), or L (low). All other types are designated by an additional number following the letter which, when multiplied by a factor, gives the approximate upper viscosity limit. The factor and applicable concentration appear below.

Viscosity Type Factor Concentration, %
High
Medium
Low
1,000
100
10
1
2
2

Solutions of all CMC types display pseudoplastic behavior. Some types, particularly those of higher molecular weight and lower substitution, also show thixotropic behavior in solution. These thixotropic solutions will possess varying amounts of gel strength and are used where suspension of solids is required. The “S,” 9, and 12 types produce solutions with little or no thixotropy, and are utilized where smooth solutions without structure are required.

Specific properties are available in certain other types. For example, the “O” type, 7HOF, provides the best solubility and storage stability in acid media.

Particle Size
Aqualon CMC is available in several different particle sizes to facilitate handling and use in processing operations such as solution preparation and dry-blending. Screen analysis is given here for three of the types. Other types are available.

Designation Description Particle Size (e)
None Regular On U.S. 30, %, max 1
On U.S. 40, %, max 5
C Coarse On U.S. 20, %, max 1
Through U.S. 40, %, max 55
Through U.S. 80, %, max 5
X Fine On U.S. 60, %, max 0.5
Through U.S. 200, %, min 80
(e)AII screens are U.S. Bureau of Standards sieve series.

Product Coding
An example of the coding used for ordering Aqualon CMC follows:

For cellulose gum Type 7H3SCF:

7
H
3
S
C
F
means that the typical degree of substitution is approximately 0.7.
means high viscosity.
means that the viscosity of a 1% solution is in the range of 3,000 cps.
means smooth solution characteristics.
means coarse particle size.
means food grade.

Aqualon can tailor the chemical and physical properties of CMC to meet special requirements. Users are encouraged to discuss their needs with their technical representative, or to call the 800 number shown on the back cover for product information.

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