Good and Poor Water-Holding Capacity of Hydroxypropyl Methyl Cellulose
A Distinction Between Good and Poor Water-Holding Capacity of Hydroxypropyl Methyl Cellulose
The water-holding capacity of methyl cellulose ethers under high temperature conditions is an important indicator to distinguish the quality of methyl cellulose ethers.
The factors such as the air temperature, the temperature and wind pressure speed will affect the evaporation rate of water in cement mortar and plaster-based products. Therefore, in different seasons, products with the same addition amount of Hydroxypropyl Methyl Cellulose may have some differences in water retention effects. In the specific construction, the water retention effects of slurry can be adjusted by increasing or decreasing the addition amount of Hydroxypropyl Methyl Cellulose.
Excellent Hydroxypropyl Methyl Cellulose series products can effectively solve the problem of water retention at high temperatures. In the hot season, especially the thin layer construction in hot and dry regions and the sunny side requires high quality Hydroxypropyl Methyl Cellulose to improve the water-holding capacity of slurry.
High quality Hydroxypropyl Methyl Cellulose has very good uniformity. Its methoxy groups and hydroxy propoxy groups are uniformly distributed along the chain of the cellulose molecules. It can improve the the ability to form the hydrogen key by the association of oxygen atoms on the hydroxyl group and ether bond with water and make free water into bound water, so as to effectively control the the evaporation of water caused by high temperatures and then to achieve high water-holding capacity.
High quality methyl cellulose can be uniformly and efficiently dispersed in the cement mortar and gypsum-based products, and wrap all the solid particles and form a wet film. The moisture in it will be gradually released in a considerable length of time, and then generate a hydration reaction with inorganic cementitious materials, so as to ensure the bonding strength and compressive strength of materials.
Therefore, under the hot summer construction, in order to achieve water retention effect, a sufficient amount of the high quality Hydroxypropyl Methyl Cellulose product should be added in accordance with the formula. Otherwise, there will be excessive drying, leading to insufficient hydration, strength reduction, cracking, hollowing, shedding and other quality problems. Meanwhile, it also increases the difficulty of construction for workers. However, as the temperature decreases, the addition amount of Hydroxypropyl Methyl Cellulose can be gradually reduced, but the same water retention effects can be achieved.
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