The water retention of hydroxypropyl methylcellulose HPMC products is often affected by the following factors:
1. Cellulose ether HPMC uniformity
The homogeneously reacted HPMC has a uniform distribution of methoxy and hydroxypropoxy groups and a high water retention rate.
2. Cellulose ether HPMC thermogel temperature
The thermal gel has a high temperature and a high water retention rate; on the contrary, the water retention rate is low.
3. Cellulose ether HPMC viscosity
When the viscosity of HPMC rises, the water retention rate also increases; when the viscosity reaches a certain level, the increase of the water retention rate tends to be gentle.
4. Cellulose ether HPMC addition
The larger the amount of cellulose ether 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 rapidly with the increase of the addition amount; when the addition amount further increases, the increase rate of the water retention rate becomes slower.
Water retention function and principle of hydroxypropyl methylcellulose HPMC:
In the cement mortar and gypsum-based slurry, cellulose ether HPMC mainly plays the role of water retention and thickening, which can effectively improve the adhesion and sag resistance of the slurry.
Factors such as air temperature, temperature and wind pressure rate affect the volatilization rate of moisture 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 added. In the 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 methyl cellulose ether under high temperature conditions is an important indicator for distinguishing the quality of methyl cellulose ether. The excellent HPMC series products can effectively solve the problem of water retention at high temperatures. In the hot season, especially in the hot and dry areas and the thin layer of the sunny side, high quality HPMC is required to improve the water retention of the slurry.
High-quality cellulose HPMC can be uniformly and effectively dispersed in cement mortar and gypsum-based products, and wrap all solid particles, and form a wet film, the moisture in the base is gradually released for a long time, and inorganic glue The condensate material undergoes a hydration reaction to ensure the bond strength and compressive strength of the material. Therefore, in the high temperature summer construction, in order to achieve the water retention effect, it is necessary to add high quality HPMC products according to the formula. Otherwise, there will be insufficient hydration, strength reduction, cracking, hollowing and falling off due to excessive drying. The problem also increases the difficulty of construction of workers. As the temperature decreases, the amount of HPMC added can be gradually reduced, and the same water retention effect can be achieved.