Views:0 Author:Site Editor Publish Time: 2020-05-25 Origin:Site
Water Retention of Cellulose Ethers HPMC, HEMC, HEC
Water retention of cellulose ether (HPMC, HEMC, HEC): In the production of building materials, especially dry powder mortar, cellulose ether plays an irreplaceable role, especially in the production of special mortar (modified mortar), it is an indispensable important part .
The important role of water-soluble cellulose ethers (HPMC, HEMC, HEC) in mortar mainly has three aspects, one is excellent water retention capacity, the other is the influence on the consistency and thixotropy of mortar, and the third is the interaction with cement.
The water retention function of cellulose ethers (HPMC, HEMC, HEC) depends on the water absorption of the base layer, the composition of the mortar, the thickness of the mortar layer, the water demand of the mortar, and the setting time of the setting material. The water retention of cellulose ethers (HPMC, HEMC, HEC) itself comes from the solubility and dehydration of cellulose ethers (HPMC, HEMC, HEC) itself.
As we all know, although the cellulose molecular chain contains a lot of OH groups with strong hydration, it is not soluble in water itself, because the cellulose structure has a high degree of crystallinity. The hydration capacity of the hydroxyl group alone is not enough to pay for the strong hydrogen bonding and van der Waals force between the molecules. Therefore, it only swells and does not dissolve in water. When the substituent is introduced into the molecular chain, not only the substituent breaks the hydrogen chain, but also the hydrogen bond between the chains is broken due to the wedge of the substituent between adjacent chains. The greater the distance. The greater the effect of breaking the hydrogen bond, after the cellulose lattice expands, the solution enters, and the cellulose ether becomes water-soluble, forming a high-viscosity solution. When the temperature increases, the polymer hydration weakens, and the water between the chains is expelled. When the dehydration effect is sufficient, the molecules begin to aggregate and form a three-dimensional network structure gel to fold out.