1. hygroscopicity
Carboxymethylcellulose sodium CMC has the same water absorption as other water-soluble glues. Its humidity balance increases with the increase of humidity and decreases with the increase of temperature. The higher the D.S, the greater the air humidity, and the product’s The stronger the water absorption. If the bag is opened and placed in air with a high humidity content for a period of time, its moisture content can reach 20%. When the water content is 15%, the powder form of the product will not change. When the water content reaches 20%, some particles will accumulate and stick to each other, reducing the fluidity of the powder. CMC will increase in weight after absorbing moisture, so some unpacked products must be placed in airtight containers or stored in a dry place.
2. Carboxymethyl Cellulose Sodium CMC Dissolved
Carboxymethylcellulose sodium CMC, like other water-soluble polymers, exhibits swelling before dissolving. When a large amount of carboxymethylcellulose sodium CMC solution needs to be prepared, if each particle is uniformly swollen, then Product dissolves quickly. If the sample is thrown into the water quickly and sticks to a block, a “fish eye” will be formed. The following describes the method of quickly dissolving CMC: slowly put CMC into water under moderate stirring; CMC is pre-dispersed with a water-soluble solvent (such as ethanol, glycerin), and then slowly add water under moderate stirring; If other powdered additives need to be added to the solution, first mix the additives and CMC powder, and then add water to dissolve; for the convenience of users, instant granule and powder instant products are launched.
3. Rheology of Sodium Carboxymethyl Cellulose CMC Solution
Sodium carboxymethyl cellulose CMC solution is a non-Newtonian fluid, which shows low viscosity at high speed, that is to say, because the viscosity value of sodium carboxymethyl cellulose CMC depends on the measurement conditions, so “apparent viscosity” is used to describe its nature.
Shown on the rheological curve diagram: The nature of non-Newtonian fluids is that the relationship between the shear rate (rotational speed on the viscometer) and the shear force (torque of the viscometer) is not a linear relationship, but a curve.
Carboxymethyl cellulose sodium CMC solution is a pseudoplastic fluid. When measuring the viscosity, the faster the rotation speed, the smaller the measured viscosity, which is the so-called shear thinning effect.
4. Carboxymethyl Cellulose Sodium CMC Viscosity
1) Viscosity and average degree of polymerization
The viscosity of sodium carboxymethylcellulose CMC solution mainly depends on the average degree of polymerization of the cellulose chains forming the framework. There is an approximately linear relationship between viscosity and average degree of polymerization.
2) Viscosity and concentration
The relationship between viscosity and concentration of some types of sodium carboxymethylcellulose CMC. Viscosity and concentration are roughly logarithmic. Sodium carboxymethyl cellulose CMC solution can produce quite high viscosity at low concentration, this characteristic makes CMC can be used as an excellent thickener in the application.
3) Viscosity and temperature
The viscosity of carboxymethylcellulose sodium CMC aqueous solution decreases with the increase of temperature, regardless of the type and concentration, the trend of the solution viscosity and temperature relationship curve is basically the same.
4) Viscosity and pH
When the pH is 7-9, the viscosity of CMC solution reaches its maximum and is very stable. The viscosity of sodium carboxymethylpyramid will not change greatly within the pH range of 5-10. CMC dissolves faster in alkaline conditions than in neutral conditions. When pH>10, it will cause CMC to degrade and reduce the viscosity. When an acid is added to the CMC solution, the stability of the solution is reduced because the H+ in the solution replaces the Na+ on the molecular chain. In strong acid solution (pH=3.0-4.0) semi-sol starts to form, which reduces the viscosity of the solution. When pH<3.0, CMC starts to be completely insoluble in water and forms CMC acid.
CMC with high degree of substitution is stronger in acid and alkali resistance than CMC with low D.S; CMC with low viscosity is stronger in acid and alkali resistance than CMC with high viscosity.
Post time: Jan-28-2023