The type, quantity and distribution of the substituent groups on the cellulose main chain determine the types and properties of ethers. The hydroxyl group on the cellulose ether molecular chain produces intermolecular oxygen bonds, which can improve the uniformity and completeness of cement hydration; increase the consistency of mortar, change the rheology and compressibility of mortar; improve the crack resistance of mortar; Entraining air, improving the ease of mortar. Cellulose ether has excellent properties such as thickening, emulsification, suspension, film formation, protective colloid, moisture retention, and adhesion, and is an important admixture in dry-mixed mortar.
|Chemical name||Methyl Hydroxyethyl Cellulose|
|Synonym||Cellulose ether, 2-hydroxyethyl methyl cellulose, Cellulose, 2-hydroxyethyl methyl ether, hydroxyethyl Methyl cellulose, MHEC, HEMC|
|Product Grade||MHEC MH40M|
|Solubility||Water Soluble Cellulose ether|
|Physical form||White to off-white cellulose powder|
|Viscosity Brookfield 2% solution||16000-24000mPa.s|
|Viscosity NDJ 2% solution||32000-48000mPa.S|
|Mesh size||99% pass 100mesh|
Kima Chemical MHEC MH40M methyl hydroxyethyl cellulose is used in dry-mixed mortar.
① Good water retention. MHEC can ensure that the mortar will not cause problems such as sanding, powdering and strength reduction of the product due to lack of water and incomplete cement hydration. improve uniformity, Usability and product hardening, etc. When the amount of MHEC added is greater than 0.08%, with the increase of HPMC amount, the yield stress and frown viscosity of mortar also increase.
② As an air-entraining agent. When the amount of MHEC is 0.5%, the air content is the largest, about 55%; when the amount is more than 0.5%, the air content of the mortar decreases gradually with the increase of the addition amount, and reduces the flexural strength and compressive strength.
③ Improve workability. The addition of MHEC facilitates carding of thin-layer mortar and paving of plastering mortar. MHEC can delay the hydration of mortar particles, DS is the most important factor affecting hydration, and the effect of methoxyl content on delayed hydration is greater than that of hydroxyethyl content.
It should be noted that cellulose ether has a double effect on the performance of mortar, and it can play a good role if used properly, but it will have a negative effect if used improperly. The performance of dry-mixed mortar is firstly related to the adaptability of cellulose ether, and the applicable cellulose ether is also related to factors such as the amount and order of addition. In practical applications, a single type of cellulose ether can be selected, or different types of cellulose ether can be used in combination.