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CMC For Construction Cellulosic Varieties
Jul 06, 2017

CMC For Construction Cellulosic varieties

Hydroxypropylmethylcellulose (HPMC) Hydroxypropylmethylcellulose is a rapidly growing variety of cellulose in recent years. Is a mixture of refined cotton by alkalization treatment, with propylene oxide and methyl chloride as etherification agent, through a series of reactions made of non-ionic cellulose mixed ether. The degree of substitution is generally 1.2 to 2.0. Its nature by the methoxy content and the proportion of hydroxypropyl content is different, and there are differences. (1) hydroxypropyl methyl cellulose soluble in cold water, hot water will encounter difficulties. But its gelatinization temperature in hot water is significantly higher than that of methyl cellulose. In the cold water dissolved, compared with methyl cellulose also has a big improvement. (2) The viscosity of hydroxypropylmethylcellulose is related to the molecular weight, and the molecular weight is high. The temperature also affects its viscosity, the temperature rises, and the viscosity decreases. But its viscosity is higher than the effect of high temperature than methyl cellulose. The solution is stored at room temperature is stable. (3) Hydroxypropyl methyl cellulose water retention depends on its added amount, viscosity, etc., the same amount of water retention rate is higher than methyl cellulose. (4) hydroxypropyl methyl cellulose on the acid and alkali with stability, the aqueous solution in the pH = 2 ~ 12

The range is very stable. Caustic soda and lime water, its performance is not much impact, but the alkali can speed up its dissolution rate, and the viscosity of the pin has improved. Hydroxypropylmethylcellulose has a stability to the general salt, but when the salt solution concentration is high, the viscosity of the hydroxypropylmethylcellulose solution tends to increase. (5) Hydroxypropylmethylcellulose can be mixed with a water-soluble polymer compound to become a homogeneous, higher viscosity solution. Such as polyvinyl alcohol, starch ether, plant gum and so on. (6) Hydroxypropylmethylcellulose has better resistance to enzymatic than methylcellulose, and the possibility of degradation of its solution is lower than that of methylcellulose. The adhesion of hydroxypropylmethylcellulose to mortar construction is higher than that of methyl cellulose. Carboxymethylcellulose (CMC) is treated with natural fibers (cotton, etc.) through alkali, and then subjected to a series of reaction treatments with monochloroacetic acid as an etherifying agent to form ionic cellulose ethers. Its degree of substitution is generally 0.4 ~ 1.4, its performance by the degree of substitution greater impact. Its aqueous solution has the functions of thickening, film forming, bonding, moisture retention, colloidal protection, emulsification and suspension. It is widely used in petroleum, food, medicine, textile and paper industry. It is one of the most important cellulose ethers. (1) carboxymethyl cellulose hygroscopicity is large, the general conditions of storage will contain greater water. (2) carboxymethyl cellulose aqueous solution does not produce gel, with the temperature rise and viscosity decreased, the temperature exceeds 50 ℃, the viscosity is irreversible. (3) its stability is greatly affected by pH. Generally used in gypsum-based mortar, can not be used in cement-based mortar. In the case of overbased, it will lose its viscosity. (4) its water retention is far lower than methyl cellulose. The gypsum-based mortar has a retarding effect, and reduce its strength. But the price of carboxymethyl cellulose was significantly lower than that of methylcellulose.

 CMC as a water-soluble food additives, with thickening, stability, emulsification, shaping and other effects in the food industry has a wide range of uses. CMC is the abbreviation of English CarboxyMethylCellulose, Chinese called sodium carboxymethyl cellulose, the molecular formula C6H7 (OH) 2OCH2COONa, is the natural cellulose fiber modified by the fiber derivatives, is one of the important water-soluble polymer. CMC has a thickening, dispersion, suspension, bonding, film, protective colloid and water protection and other excellent performance, widely used in food, medicine, toothpaste and other industries. CMC is white or slightly yellow powder, granular or fibrous solid, odorless, tasteless, non-toxic. CMC is a macromolecular chemical, can be water swelling, swelling in water, you can form a transparent viscous glue, in the acidity of the performance of neutral. Solid CMC for light and room temperature are more stable, in a dry environment, can be long-term preservation. CMC has a hygroscopic character, its degree of moisture and atmospheric temperature and relative humidity, when reached equilibrium, no more moisture. CMC aqueous solution has excellent adhesion, thickening, emulsification, suspension, film, protective colloid, to maintain moisture, anti-enzymatic and metabolic inertia and other properties. CMC aqueous solution with tin, silver, aluminum, lead, iron, copper and some heavy metals meet, precipitation reaction occurs; CMC aqueous solution with calcium, magnesium, salt coexistence, does not produce precipitation, but will reduce the CMC aqueous solution viscosity.