Air-entraining effect of cellulose ether

Cellulose ethers are synthetic polymers made from natural cellulose and chemically modified. Cellulose ether is a derivative of natural cellulose. Unlike synthetic polymers, cellulose ether production is based on cellulose, the most basic material, a natural polymer compound. Due to the specificity of the natural cellulose structure, cellulose itself does not have the ability to react with etherizing agents. However, after the treatment of solubilizers, the strong hydrogen bonds between and within the molecular chains are destroyed, and the hydroxyl group activity is released into alkali cellulose with the ability to react, and after the reaction of the etherizing agent an OH group is converted into an OR group to obtain cellulose ether.

Cellulose ethers have obvious air-entraining effect on freshly mixed cementitious materials. Cellulose ethers have both hydrophilic (hydroxyl, ether) and hydrophobic (methyl, glucose ring) groups and are surfactants with surface activity and thus have an air-entraining effect. The air-entraining effect of cellulose ether will produce the “ball” effect, which can improve the working performance of the fresh material, such as increasing the plasticity and smoothness of the mortar during operation, which is beneficial to the spreading of mortar; it will also improve the yield of mortar and reduce the cost of mortar production; however, it will increase the porosity of the hardened material and reduce its strength and elastic modulus, etc. Mechanical properties.

As a surfactant, cellulose ether also has a wetting or lubricating effect on cement particles, which together with its air-entraining effect increases the fluidity of cementitious materials, but its thickening effect reduces the fluidity, and the effect of cellulose ether on the fluidity of cementitious materials is a combination of plasticizing and thickening effects. Generally speaking, when the amount of cellulose ether is very low, it mainly shows the effect of plasticization or water reduction; when the amount is high, the thickening effect of cellulose ether increases rapidly, and its air-entraining effect tends to saturate, so it shows the thickening effect or increases the water requirement.