Views:0 Author:Site Editor Publish Time: 2021-01-21 Origin:Site
The hydration capacity of the hydroxyl group alone is not enough to cover the strong hydrogen bonds and van der Waals forces between molecules. Therefore, it only swells and does not dissolve in water. When a substituent is introduced into the molecular chain, not only the substituent destroys the hydrogen chain, but also the hydrogen bond between the chains is broken due to the wedging of the substituents 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 rises, the hydration of the polymer weakens, and the water between the chains is expelled. When the water removal effect is sufficient, the molecules begin to aggregate, forming a three-dimensional network structure gel and fold out.
Factors affecting the water retention of mortar include cellulose ether viscosity, addition amount, particle fineness and use temperature.
The greater the viscosity of the cellulose ether, the better the water retention performance. Viscosity is an important parameter of MC performance. At present, different MC manufacturers use different methods and instruments to determine the viscosity of MC. The main methods are Haake Rotovisko, Hoppler, Ubbelohde and Brookfield. For the same product, the viscosity results measured by different methods are very different, and some are even doubled. Therefore, when comparing the viscosity, it must be carried out between the same test methods, including temperature, rotor, etc.
To be continued..
Hydroxypropyl methyl cellulose is divided into two kinds of ordinary hot soluble cold water instantly soluble. Hydroxypropyl methyl cellulose uses are 1, Gypsum series In the gypsum series of products, cellulose ethers are mainly used to retain water and increase smoothness. Together they play a cer