CELLULOSE -GREEN AGROCHEM

Sodium carboxymethyl cellulose (Na CMC) is used for its thickening and swelling properties in a wide range of complex formulated products for pharmaceutical, food, home, and personal care applications, as well as in paper, water treatment, and mineral processing industries.

To design Na CMC solutions for applications, a detailed understanding of the concentration-dependent rheology and relaxation response is needed. We address this here by investigating aqueous Na CMC solutions over a wide range of concentrations using rheology as well as static and dynamic light scattering. The concentration dependence of the solution specific viscosities η_sp could be described using a set of three power laws, as predicted from the scaling theory of polyelectrolytes.

Alternatively, a simpler approach could be used, which interpolates between two power law regimes and introduces only one characteristic crossover concentration. We interpret the observed behavior as a transition from the semidilute nonentangled to the entangled concentration regimes; this transition behavior was not observed in the solution structure, as determined using static light scattering. Dynamic light scattering revealed three relaxation modes.

The two fastest relaxations were assigned as the “fast” and “slow” relaxation modes typically observed in salt-free or not fully screened polyelectrolyte solutions within the semidilute concentration range. The third, typically weak mode, was attributed to the presence of a small amount of poorly dissolved cellulose residuals.

Since filtration altered the solution behavior, without sufficiently removing the residuals, data collection and processing were adapted to account for this, which facilitated a detailed light scattering investigation of the original solutions, relevant for industrial applications. The relaxation time characterizing the fast mode, τ_f, was concentration independent; whereas the relaxation time of the slow mode, τ_s, demonstrated similar crossover behavior as observed for the specific viscosity, further demonstrating the dynamic nature of the crossover.

Carboxymethylcellulose is a cellulose derivative that consists of the cellulose backbone made up of glucopyranose monomers and their hydroxyl groups bound to carboxymethyl groups. It is added in food products as a viscosity modifier or thickener and emulsifier. It is also one of the most common viscous polymers used in artificial tears, and has shown to be effective in the treatment of aqueous tear-deficient dry eye symptoms and ocular surface staining . The viscous and mucoadhesive properties as well as its anionic charge allow prolonged retention time in the ocular surface . Sodium carboxymethylcellulose is the most commonly used salt.

A dish of ice cream, a tube of toothpaste, some laundry detergents and artificial teardrops all rely upon the synthetic gum, sodium carboxymethyl cellulose for their creamy taste, squeezability, soil-lifting strength and lubricating effect. Sodium carboxymethyl is derived from natural cellulose treated with chloroacetic acid. The U.S. Food and Drug Administration (FDA) classifies sodium carboxymethyl cellulose as generally recognized as safe (GRAS) for use as a food additive.

Physical Properties of Sodium Carboxymethyl Cellulose

In dry form sodium carboxymethyl is a white or slightly yellowish, amber or grayish powder. It is odorless and tasteless. Sodium carboxymethyl cellulose dissolves readily in water. It is hygroscopic, meaning it takes up and holds onto moisture. Its hygroscopic properties are partially responsible for its success as a food and drug additive.

Use as a Thickener

Sodium carboxymethyl is added to some products as a thickener and as a dispersant. By controlling the amount of sodium carboxymethyl added, the manufacturer can fine-tune the feel of the food or medicine in the mouth and as it is swallowed. As a thickener, sodium carboxymethyl makes it easier for ingredients to be dispersed evenly throughout the mixture and stay evenly dispersed. It helps keep solids suspended in liquids and acts as an emulsifier, keeping lotions and creams from separating.

Effect on Pourability

Adding sodium carboxymethyl cellulose to liquids changes the viscosity of the liquid. Sodium carboxymethyl cellulose molecules normally bind to each other; water squeezes in and breaks up the bonds. The viscosity or resistance to pouring of a liquid depends on the amount of sodium carboxymethyl cellulose added. Sodium carboxymethyl cellulose can be used to make thick, slow-pouring gels or soothing, tear-like eye lubricants.

As a Food Additive

Sodium carboxymethyl cellulose is often added to foods as a stabilizer. As a generally recognized safe ingredient, the FDA does not have to approve its use in foods. Sodium carboxymethyl cellulose can keep ice cream from separating. It is also added as a bulking agent, emulsifier, firming agent, gelling agent, glazing agent, humectant and thickener. It is found in chocolate milk, cocoa, eggnog, condensed milk, powdered milk, some cheeses, daily spreads, processed fruit, breakfast cereals, sausage casings, custards, seasonings and condiments, soups and broths, sauces, dietetic foods, beer, cider and much more.

Use in Reusable Ice Packs

Sodium carboxymethyl cellulose is sometimes used to make reusable ice packs. When combined with water and other substances such as propylene glycol, sodium carboxymethyl forms a eutectic mixture–a mixture whose freezing point is lower than that of any of the mixture constituents. One product on the market has a freezing point of -23 degrees Celsius (-9.4 Fahrenheit). These reusable ice packs are usually nontoxic and environmentally friendly.

 Sodium CarboxymethylCellulose (Sodium CMC) product is a kind of important Cellulose ether , a polyanion product with good water solubility obtained from plant fiber by means of chemical modification. It is easily soluble in cold water and has dispersibility. Moreover, it has some very unusual physical and chemical properties such as being difficult to get bad and being physiologically harmless.

Sodium CMC  (Sodium CarboxymethylCellulose) has very unusual and valuable physical and chemical properties such as emulsifying dispersion and solid dispersion properties, as well as being difficult to get bad and being physiologically harmless. It is a natural polymer derivative with wide application. sodium cmc has many excellent properties such as thickening, dispersing, suspending, adhesive, colloid protecting and water-retaining properties, widely used in food, medicine and toothpaste industries. sodium cmc is a kind of macromolecular chemical substance and can absorb water and swell. When it swells in water, it can form transparent thick solution. It is neutral in pH value.

Sodium CMC  is white or slightly yellowish fibrous powder, or white powder in appearance. It is odorless, tasteless, non-toxic, easily soluble in cold or hot water to form colloid and the solution is neutral or slightly alkaline. However, it is insoluble in organic solvents such as ethanol, diethyl ether, isopropanol and acetone but soluble in ethanol or acetone solutions containing 60% water. Besides, it has hygroscopicity and stability to light and heat. The viscosity decreases with the rise of temperature. In the pH value 2-10, the solution is stable; when the pH value is lower than 2, it will separate out solids; if the pH value is higher than 10, the viscosity will decrease. The thermo-chromic temperature is 227℃ and the carbonization temperature is 252℃. The surface tension of 2% aqueous solution is 71mn/n.

The main physical and chemical indicators of sodium carboxymethyl cellulose products are the viscosity, DS (degree of substitute), pH value, purity and heavy metals.

Solubility of sodium cmc

Sodium CMC  is a natural hydrophilic substance and when sodium carboxymethyl cellulose particles disperse in water, it will immediately swell and then dissolve.

1. Under the condition of stirring, adding sodium cmc slowly helps to accelerate dissolution.

2. Under the condition of heating, adding sodium cmc dispersedly can increase the dissolution rate, but the heating temperature cannot be too high and is appropriate within 50-60°C.

3. If it is used by blending with other materials, first mix the solids together and then dissolve, and in this way, the dissolution speed can also be enhanced.

4. Add a kind of organic solvents which are insoluble with sodium cmc but soluble with water such as ethanol and glycerin and then dissolve, so in this way, the solution speed can be very fast.

Aspects of Determining the Time Needed for Complete Dissolution of sodium cmc

1. sodium cmc can totally conglutinate with water and there doesn’t exist solid-liquid separation phenomenon between the two.

2. The mixed thick colloid is in a uniform state and the surface is flat and smooth.

3. The mixed thick colloid is nearly colorless transparent in color and have no particles in it.

From the moment sodium cmc is put into the pill tank and mix with water to the time sodium cmc is completely dissolved, it may take 10-20 hours.

PAC(Polyanaionic Cellulose), which is a water-soluble cellulose ether derivative prepared by chemical modification of natural cellulose. It is an important water-soluble cellulose ether. It is usually used in its sodium salt and is widely used in petroleum Drilling, especially salt water wells and offshore oil drilling.
Polyanionic cellulose is widely used and can be used in all industries available for carboxymethylcellulose (CMC) to provide more stable application performance.
E.g:
1. Can be used as a textile yarn in the textile industry instead of starch gauze sizing agent;
2. Paper pulp by adding pulp, can improve the paper’s longitudinal strength and smoothness, improve the paper’s oil resistance and ink absorption;
3. Daily chemical industry for the preparation of soap and synthetic detergent;
4. Rubber industry as latex stabilizer;
5. In addition, in the fine chemical processing such as paint, food, cosmetics, ceramic powder, leather, etc., as a thickening agent, emulsion stabilizer, crystal forming preventing agent, thickener, binder, suspending agent, water retaining agent, Dispersant and so on.
Chemical properties

1. High degree of substitution: Substitution value 0.85-1.4.

2. Heat stability: the stability of the aqueous solution below 80 ℃, when the temperature is as high as close to 150 ℃ can still show a certain viscosity and can be maintained for about 48h.

3. Acid and alkali resistance: PH value in the 3-11 range of stable performance, can be applied to all kinds of polar harsh environment.

4. Good compatibility: with other cellulose ethers, water-soluble adhesives, softeners, resins, etc. can be compatible; when the degree of substitution of PAC more than 1.2, gradually show oil-soluble.

5. Good solubility: with a simple mixing device can be quickly dissolved in cold water and hot water; hot water dissolution faster; instant PAC within a few minutes can be fully dissolved, greatly improving the use of convenience And production efficiency.

6. Good stability: PAC aqueous solution with light stability, longer shelf life; anti-bacterial mildew performance, no fermentation.

7. Very low usage: Due to the high degree of substitution and high stability of the PAC itself, it is only 30% to 60% of the amount of carboxymethylcellulose (CMC) in the same environment, at a certain extent Lower the cost of the use of the enterprise. Has a high cost advantage; while saving the consumption of raw materials, with high economic and social benefits.

8. Polyanionic cellulose (PAC) is the main raw material of refined cotton, its own pharmacological effects, in the physical harmless, green production technology.

9. Polyanionic cellulose can be used for downhole operations in deep wells.
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The base cellulose is first prepared and then reacted with an etherifying agent
And the remaining base, the product is isolated and purified, dried and pulverized to obtain the product.
    In general, when the HPC is prepared by the slurry technique, the alkali cellulose is generally powdered or pulverized
Cotton as raw material, dispersed in organic thinner, and NaOH aqueous solution at room temperature and obtained. Commonly used
The organic diluent is alcohol (such as isopropyl alcohol, tert-butanol), acetone, also useful etherification agent propylene oxide. The composition of alkali cellulose is essential for the preparation of products with good water solubility and uniformity.
The composition ratio of the ratio of cellulose to NaOH is 1: (0.2 to 0.4); the mass ratio of the aqueous paste to the cellulose raw material
Ratio of 1: (0.15 to 0.30), the water content should be as low as possible to reduce side effects. Diluent and cellulose quality
Ratio, depending on the reaction equipment in the 3 to 15: 1 between the changes.
    The organic diluent used in the etherification reaction may be the IPA, TBA, etc. used for the alkalization, and the organic diluent
With non-polar such as hexane, toluene or the like. It is generally believed that the reaction rate below 50 ℃ is very slow
80 ℃ above the side reaction is very fast, so the reaction temperature to 55 ~ 85 ℃ is appropriate, the reaction time of 5 ~ lOh.
    HPC purification is much simpler than the HEC, only to neutralize the separation of the crude into more than 85 ℃
Hot water repeatedly rinse, you can water-soluble salts, propylene glycol and other debris removed to achieve the purpose of purification.
    The low-substituted HPC can be prepared by a conventional slurry process. While the high degree of substitution HPC production with two
Step to avoid excessive expansion during alkalization, help to improve the solubility, propylene oxide utilization and products
purity. The inert solvent in the alkalization process may be an alcohol of 3 to 5 carbon atoms (e.g., isopropanol, pentanol, tert
Butanol), dioxane, acetone and propylene oxide, and the etherification process of non-solvent can be used aliphatic and aromatic
Perfume, and alkyl ethers.
    The resulting HPC can be washed with hot water (because it is insoluble above 45 ° C), well-dispensed HPC
The best part of the product can also be treated with glyoxal and then dried and packaged. Many patents have been reported about the deal
The method of the improvement comprises the drying of the alkali cellulose in the intermediate step, the infiltration of the alkali cellulose to reduce
NaOH concentration, in the process of hydroxypropylation with amine catalyst.
    Here are two HPC production processes.
    (1) 100 parts of wood pulp (100 mesh), 50 to 100 parts of IPA and 280 parts of PO were added to a kneader
, In the Nz atmosphere stirring 20min. The temperature was then raised to 60 ° C and reacted at this temperature for 5 h, raising the temperature
Reaction to 70 ° C th. The reaction mixture was separated and the crude product was allowed to neutralize, washed with hot water at about 90 ° C,
The purified product was centrifuged and centrifuged to give HPC. The MS was 3.6, the etherification efficiency was 46. 0%
Dissolved in water and ethanol, 2% solution of the light transmittance of 95% or more. If the raw material pulp fineness is not reached
100 or more, or increase the amount of 1PA and PO, will reduce the MS and etherification efficiency.
    (2) 1 part of powdered pulp was added to a mixture consisting of 13 parts of TBA, 1.4 parts of water and 0.1 part of NaOH
And the mixture was stirred at 25-40 ° C to prepare an alkali fiber pulp. Centrifuge the filter to remove most of the
TBA after the press ratio of 1.52, containing fiber turbidity 61.3%, NaOH 6.3%, water 15. 4% and
TBA17. O% of the alkali cellulose. 6.5 parts of this alkali cellulose was added to the etherification reactor and replaced with nitrogen
After the addition of 28 parts of hexane and 6.4 parts of PO, stirring, heating, in vain 80 ℃ reaction 3h. At this point has been generated
HPC has a MS of 2.3. The reaction mixture was cooled to 50 ° C, 2 parts of water and 3.6 parts of PO were added and the temperature was warmed
Degrees up to 80 ℃ reaction 2h or so. Neutralize, remove the crude product and wash with hot water, dry, crushed to produce
Product HPC. The MS is 3.5, the etherification efficiency is 50% in water, methanol, ethanol and IPA, TBA
Dissolved, 2% solution of light transmittance of 93% or more.
    Theoretical analysis and practical experience have shown that the full pulverization of cellulose raw materials is necessary. Can be crushed
To reduce the crystallinity of the cellulose, to improve the accessibility of the reaction, but also easy to make it more evenly dispersed in the inert media