Views:1 Author:Site Editor Publish Time: 2020-05-24 Origin:Site
Cellulose Ethers in Ready Mixed Mortar
Cellulose Ethers | MC | HPMC | HEMC| Ready Mixed Mortar
In the ready-mixed mortar, the amount of cellulose ether added is very low, but it can significantly improve the performance of the wet mortar, which is the main additive that affects the construction performance of the mortar. Reasonable selection of different varieties, different viscosities, different particle sizes, different degrees of viscosity and the amount of cellulose ether added will have a positive impact on the performance improvement of dry powder mortar. At present, many masonry and plastering mortars have poor water retention properties, and water slurry separation will occur after a few minutes of standing.
Water retention is an important performance of methyl cellulose ether, and it is also the performance that many dry powder mortar manufacturers in China, especially those with high temperature in the south, pay attention to. The factors that affect the water retention effect of dry powder mortar include the amount of MC added, the viscosity of MC, the fineness of the particles and the temperature of the use environment.
Cellulose ether is a synthetic polymer made from natural cellulose as a raw material and chemically modified. Cellulose ether is a derivative of natural cellulose. The production of cellulose ether is different from synthetic polymers. Its most basic material is cellulose, a natural polymer compound. Due to the particularity of the natural cellulose structure, cellulose itself has no ability to react with etherifying agents. However, after the treatment with the swelling agent, the strong hydrogen bonds between the molecular chains and within the chain are broken, and the activity of the hydroxyl group is released into alkali cellulose with reactive ability. After the etherification agent reaction, the OH group is converted to the -OR group. Cellulose ether is obtained.
The nature of cellulose ether depends on the type, number and distribution of substituents. The classification of cellulose ethers is also based on the types of substituents, the degree of etherification, the solubility properties and the related application types. According to the type of substituents on the molecular chain, it can be divided into monoether and mixed ether. The MC we usually used is monoether, and HPMC is mixed ether. Methyl cellulose ether MC is the product of the substitution of hydroxyl groups on the natural cellulose glucose unit with methoxy groups. The structural formula is [CO H7O2 (OH) 3-h (OCH3) h] x, hydroxypropyl methyl cellulose ether HPMC It is a product obtained by replacing a part of the hydroxyl group on the unit with a methoxy group and another part with a hydroxypropyl group, the structural formula is [C6H7O2 (OH) 3-mn (OCH3) m [OCH2CH (OH) CH3] n] x Hydroxyethyl methyl cellulose ether HEMC, these are the main varieties widely used and sold on the market.