Hydroxypropyl Methyl Cellulose in Construction Grade Cellulose

Hydroxypropyl methylcellulose is a cellulose variety whose output and dosage have increased rapidly in recent years. It is a non-ionic cellulose mixed ether made by a series of reactions after alkalizing refined cotton, using propylene oxide and methyl chloride as etherifying agents. The degree of substitution is generally 1.2~2.0. Its properties vary depending on the ratio of methoxyl content to hydroxypropyl content.

1. The water retention of hydroxypropyl methylcellulose depends on its addition amount, viscosity, etc. Its water retention rate is higher than that of methylcellulose at the same addition amount.

  2. Hydroxypropyl methylcellulose is easily soluble in cold water, but will have difficulty dissolving in hot water. But its gelling temperature in hot water is significantly higher than that of methylcellulose. The dissolution in cold water is also greatly improved compared to methylcellulose.

3. Hydroxypropyl methylcellulose has better enzyme resistance than methylcellulose. The possibility of solution enzyme degradation is lower than that of methylcellulose. Hydroxypropylmethylcellulose has poorer adhesion to mortar construction. Higher than methylcellulose.

4． The viscosity of hydroxypropyl methylcellulose is related to its molecular weight. The larger the molecular weight, the higher the viscosity. Temperature will also affect its viscosity. As the temperature increases, the viscosity decreases. However, the effect of high temperature on its viscosity is lower than that of methylcellulose. Its solution is stable when stored at room temperature.

5. Hydroxypropyl methylcellulose is stable to acids and alkalis, and its aqueous solution is very stable within the pH range of 2 to 12. Caustic soda and limewater do not have much impact on its performance, but alkali can speed up its dissolution and increase its viscosity. Hydroxypropyl methylcellulose is stable to general salts, but when the concentration of the salt solution is high, the viscosity of the hydroxypropyl methylcellulose solution tends to increase.

6． Hydroxypropyl methylcellulose can be mixed with water-soluble polymer compounds to form a uniform, higher viscosity solution. Such as polyvinyl alcohol, starch ether, vegetable gum, etc.