Effects of Hydroxypropyl Methyl Cellulose(HPMC) in Dry Mortar in Construction
Molecular Formula of Hydroxypropyl Methyl Cellulose(HPMC): [C6H7O2(OH)3-m-n(OCH3)m,OCH2CH(OH)CH3]n]x
1. Hydroxypropyl Methyl Cellulose is easily soluble in cold water but difficult to be soluble in hot water. However, its gelling temperature in hot water is significantly higher than that of methyl cellulose (MC). And compared with MC, the dissolution in cold water has also been greatly improved.
2. The viscosity of Hydroxypropyl Methyl Cellulose is related to the size of the molecular weight, and the larger the molecular weight is , the higher the viscosity is. The temperature will also affect its viscosity. As the temperature increases, the viscosity decreases. However, the viscosity of Hydroxypropyl Methyl Cellulose is less affected by the temperature than Methyl Cellulose, and its solution is stable in storage at room temperature.
3. The water-retaining property of Hydroxypropyl Methyl Cellulose depends on its addition amount and viscosity. With the same addition amount, the water-retention rate of Hydroxypropyl Methyl Cellulose is higher than that of methyl cellulose (MC).
4. Hydroxypropyl Methyl Cellulose has stability to acids and bases and its aqueous solution is very stable at pH 2-12. Caustic soda and lime water have little impact on its performance. but bases can accelerate its dissolution rate and slightly increase the viscosity. Hydroxypropyl Methyl Cellulose has the stability to general salts, but the HPMC solution viscosity will tend to increase when the concentration of the salt solution is high.
5. Hydroxypropyl Methyl Cellulose can mix with water-soluble polymers and then form a uniform solution of higher viscosity, such as polyvinyl alcohol, starch ethers, and vegetable gums.
6. Hydroxypropyl Methyl Cellulose has better enzyme resistance than MC, and the possibility of enzymatic degradation of HPMC is less than that of methyl cellulose (MC).
7. Hydroxypropyl Methyl Cellulose has higher adhesion on mortar construction than methyl cellulose (MC).
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