Water Retention Role and Principle of Hydroxypropyl Methyl Cellulose HPMC.

In cement mortars and gypsum-based slurries, cellulose ether HPMC mainly acts as a water retainer and thickener, which can effectively improve the bonding and sagging resistance of the slurry.

Factors such as air temperature, temperature and wind pressure speed affect the evaporation rate of water in cement mortars and gypsum-based products. Therefore, there are some differences in the water retention effect of adding the same amount of HPMC in different seasons. The water retention effect of the slurry can be adjusted by increasing or decreasing the amount of HPMC added in the specific construction. The water retention of methyl cellulose ether under high temperature conditions is an important indicator to distinguish the quality of methyl cellulose ether. A good HPMC series can effectively solve the problem of water retention at high temperatures. In the high temperature season, especially in hot and dry areas and thin layers on sunny surfaces, 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 form hydrogen bonds with water, turning free water into bound water, thus effectively controlling the evaporation of water caused by hot weather and achieving high water retention.

High quality cellulose HPMC is evenly and effectively dispersed in cement mortar and gypsum based products and wraps all solid particles and forms a wetting film. The water in the base is gradually released over a considerable period of time and hydrates with the inorganic cementitious material, thus ensuring the bonding strength and compressive strength of the material. Therefore, in the high temperature summer construction, in order to achieve the effect of water retention, it is necessary to add a sufficient amount of high-quality HPMC products in accordance with the formula, otherwise, there will be too fast drying and caused by insufficient hydration, strength reduction, cracking, drums and peeling and other quality problems, but also increase the difficulty of workers construction. And 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 the hydroxypropyl methyl cellulose HPMC product itself is influenced by temperature and the following factors.

1. Cellulose ether HPMC homogeneity

Homogeneous reaction of HPMC, methoxy and hydroxypropoxy evenly distributed, high water retention rate.

2. Cellulose ether HPMC thermal gelation temperature

High thermal gel temperature, high water retention rate; conversely, low water retention rate.

3. Cellulose ether HPMC viscosity 

When the viscosity of HPMC rises, the water retention rate also rises; when the viscosity reaches a certain level, the increase in water retention rate tends to level off.

  4. Cellulose ether HPMC addition amount