The main performance characteristics of Hydroxypropyl MethylCellulose (HPMC)

Hydroxypropyl MethylCellulose is a rapidly growing variety of cellulose in terms of production and usage.

It is produced by treating refined cotton with alkali and using epichlorohydrin and methyl chloride as etherifying agents to produce a series of reactions, resulting in a non-ionic mixed ether of cellulose. The degree of substitution is generally 1.2~2.0.

Its properties vary with the proportion of methoxy and hydroxypropyl groups.

Hydroxypropyl MethylCellulose is soluble in cold water, but dissolution in hot water may encounter difficulties. However, its gelation temperature in hot water is significantly higher than that of Methyl Cellulose. Its dissolution in cold water is greatly improved compared to Methyl Cellulose.

The viscosity of Hydroxypropyl MethylCellulose is related to its molecular weight; higher molecular weight results in higher viscosity. Temperature also affects its viscosity, with viscosity decreasing as temperature rises. However, the influence of high temperature on viscosity is lower than that of Methyl Cellulose. Its solution is stable when stored at room temperature.

The water retention of Hydroxypropyl MethylCellulose depends on its dosage and viscosity. Under the same dosage, its water retention rate is higher than that of Methyl Cellulose.

Hydroxypropyl MethylCellulose is stable to acids and bases, and its aqueous solution is highly stable within the pH range of 2 to 12. Sodium hydroxide and lime water do not significantly affect its performance, but bases can accelerate its dissolution and slightly increase its viscosity.

Hydroxypropyl MethylCellulose is stable to general salts, but in high-concentration salt solutions, there is a tendency for the viscosity of its solution to increase.

Hydroxypropyl MethylCellulose can be mixed with water-soluble polymers to form a uniform, higher viscosity solution. Examples include polyvinyl alcohol, starch ethers, and plant gums.

Hydroxypropyl MethylCellulose exhibits better enzyme resistance than Methyl Cellulose, with a lower likelihood of enzymatic degradation in its solution.

Hydroxypropyl methylcellulose, as the primary additive in construction dry-mix mortar products, plays a crucial role in both the performance and cost of dry-mix mortar. Cellulose ethers are widely used in construction materials, with their crucial property being their ability to retain water in construction materials. Without the addition of cellulose ethers, thin-layer fresh mortar would quickly dry out, preventing cement from hydrating normally, resulting in insufficient hardening and poor bonding of the mortar. Additionally, the inclusion of cellulose ethers imparts good plasticity and flexibility to the mortar, thereby enhancing its bonding strength.