hydroxypropyl methylcellulose HPMC in Plastering MortarFebruary 2nd 2023
Water-retaining and Principle of HPMC
Hydroxypropyl methylcellulose HPMC mainly plays a role of water retention and thickening in cement mortar and gypsum-based slurry, which can effectively improve the adhesive force and sag resistance of the slurry.
Factors such as air temperature, temperature, and wind pressure speed can affect the volatilization rate of water in cement mortar and gypsum-based products. Therefore, in different seasons, there are some differences in the water retention effect of the same amount of HPMC products.
In specific construction, the water retention effect of the slurry can be adjusted by increasing or decreasing
the amount of HPMC added. The water retention of hydroxypropyl methylcellulose under high temperature conditions is an important indicator to distinguish the quality of hydroxypropyl methyl cellulose.
Excellent HPMC series products can effectively solve the problem of water retention under high temperature.
In high temperature seasons, especially in hot and dry areas and thin layers on the sunny side, high-quality HPMC is required to improve the water retention of the slurry. High-quality HPMC with very good homogeneity. Its methoxy and hydroxypropoxy groups are evenly distributed along the cellulose molecular chain, which can improve the ability of oxygen atoms on the hydroxyl and ether bonds to associate with water to form hydrogen bonds. , Make the free water into combined water, so as to effectively control the evaporation of water caused by high temperature weather, to achieve high water retention.
High-quality hydroxypropyl methylcellulose HPMC can be evenly and effectively dispersed in cement mortar and gypsum-based products, and encapsulates all solid particles, and forms a layer of wetting film.
The moisture in the base gradually changes over a long period of time. Release and hydration reaction with the inorganic gelling material, so as to ensure the bonding strength and compressive strength of the material. Therefore, in high-temperature summer construction, in order to achieve water retention effect, high-quality HPMC products need to be added in sufficient quantities according to the formula, otherwise, the quality of insufficient hydration, reduced strength, cracking, hollowing, and shedding caused by excessive drying will occur. Problems, while also increasing the difficulty of workers’ construction. As the temperature decreases, the amount of HPMC added can be gradually reduced, and the same water retention effect can be achieved.
The water retention of hydroxypropyl methyl cellulose HPMC products is affected by temperature and the following factors:
1.Homogeneity of hydroxypropyl methylcellulose HPMC
HPMC, which is uniformly reacted, has even distribution of methoxy and hydroxypropoxy groups and high water retention.
2. HPMC Thermogel Temperature
The temperature of the thermogel is high, and the water retention rate is high; otherwise, the water retention rate is low.
3. HPMC viscosity of hydroxypropyl methylcellulose
When the viscosity of HPMC rises, the water retention rate also increases; when the viscosity reaches a certain level, the increase in water retention rate tends to be gentle.
4. Addition of hydroxypropyl methylcellulose HPMC
The greater the amount of hydroxypropyl methyl cellulose HPMC added, the higher the water retention rate and the better the water retention effect. In the range of 0.25-0.6%, the water retention rate increases quickly with the increase of the amount added; when the amount is further increased, the increase of the water retention rate becomes slower.