Hydroxypropyl Methyl Cellulose (HPMC)

Hydroxypropyl methylcellulose (HPMC)

Hydroxypropyl methylcellulose HPMC is a cellulose variety whose output and consumption have been increasing rapidly in recent years. It is a non-ionic cellulose mixed ether made from refined cotton through a series of reactions using propylene oxide and methyl chloride as etherification agents after alkalization. The degree of substitution is generally 1.2 to 2.0. Its properties are different by the ratio of methoxy content and hydroxypropyl content.

(1) Hydroxypropyl methylcellulose HPMC is easily soluble in cold water, and it will be difficult to dissolve in hot water. But its gelation temperature in hot water is significantly higher than that of methyl cellulose. The dissolution in cold water is also greatly improved compared to methyl cellulose.

(2) The viscosity of hydroxypropyl methyl cellulose HPMC is related to its molecular weight. The higher the molecular weight, the higher the viscosity. Temperature also affects its viscosity, as the temperature increases, the viscosity decreases. But its high viscosity has a lower temperature effect than methyl cellulose. The solution is stable when stored at room temperature.

(3) The water retention of hydroxypropyl methylcellulose HPMC depends on its addition amount, viscosity, etc. The water retention rate under the same addition amount is higher than that of methyl cellulose.

(4) Hydroxypropyl methylcellulose HPMC  is stable to acids and alkalis, and its aqueous solution is very stable in the range of pH=2~12. Caustic soda and lime water do not have much influence on its performance, but alkali can accelerate its dissolution rate and increase viscosity. Hydroxypropyl methyl cellulose is stable to general salts, but when the concentration of the salt solution is high, the viscosity of the hydroxypropyl methyl cellulose solution tends to increase.

(5) Hydroxypropyl methylcellulose HPMC can be mixed with water-soluble polymer compounds to form a uniform and higher viscosity solution. Such as polyvinyl alcohol, starch ether, vegetable glue, etc.

(6) Hydroxypropyl methylcellulose HPMC  has better enzyme resistance than methylcellulose, and its enzymatic degradation possibility in solution is lower than that of methylcellulose.

(7) The adhesion of hydroxypropyl methyl cellulose HPMC to mortar construction is higher than that of methyl cellulose.