redispersible latex powder RDP for tile adhesivesDecember 7th 2023
Water Retention Function And Principle Of HPMC
Cellulose ether HPMC plays a main role in water retention and thickening in cement mortar and gypsum based slurry, which can effectively improve the adhesion and sag resistance of the slurry. Air temperature, temperature and wind pressure speed will affect the evaporation rate of water in cement mortar and gypsum based products.
Therefore, in different seasons, there are some differences in the water retention effect of products with the same amount of HPMC. In the specific construction, the water retention effect of slurry can be adjusted by increasing or decreasing the amount of HPMC. The water holding capacity of methyl cellulose ether at high temperature is an important index to distinguish the quality of methyl cellulose ether.
Excellent HPMC series products can effectively solve the problem of water retention under high temperature. In high temperature season, especially in hot and dry areas and thin layer construction on sunny surface, high quality HPMC is needed to improve the water retention property of slurry. High quality HPMC has very good uniformity. Its methoxy and hydroxypropoxy groups are evenly distributed along the cellulose molecular chain. It can improve the ability of oxygen atoms on hydroxyl and ether bonds to associate with water to form hydrogen bonds, so as to change free water into bound water, so as to effectively control water evaporation caused by high temperature weather and achieve high water retention.
High quality cellulose HPMC can be evenly and effectively dispersed in cement mortar and gypsum based products, and wrap all solid particles, and form a layer of wetting film. The moisture in the base will gradually release for a long time, and hydration reaction will occur with inorganic cementitious materials, so as to ensure the bonding strength and compressive strength of the materials. Therefore, in high temperature summer construction, in order to achieve water retention effect, it is necessary to add enough high-quality HPMC products according to the formula, otherwise, quality problems such as insufficient hydration, strength reduction, cracking, hollowing and falling off caused by too fast drying will occur, and at the same time, the construction difficulty of workers will be increased. With the decrease of air temperature, the amount of HPMC can be reduced gradually, and the same water retention effect can be achieved. The water retention of HPMC products is often affected by the following factors: