Hydroxyethyl methyl cellulose (HEMC) is a different kind of cellulose ether from HPMC. The substitute groups of HEMC are
hydroxyethyl and methoxy, while the substitute groups of HPMC are hydroxypropyl and methoxy. Compared with HPMC, HEMC has
more hydrophilic groups, which means it has a relatively higher gel temperature, better water retention in hot environments, and
better thermal stability.
Gel temperature is an important indicator of cellulose ether. The aqueous solution of cellulose ether has thermal gel properties.
When the temperature of the solution reaches a certain value, the viscosity of the cellulose ether begins to decrease, and the solution
is no longer uniform and transparent, but forms a white gel which separates out of the aqueous solution, and cause solution loses
viscosity. In the hot summer weather, when the mortar temperature approaches or exceeds the gel temperature of the cellulose
ether, the cllulose ether loses its water retention and thickening efects, the mortar no longer has good operability, and the bonding
strength cannot be guaranteed.
When work under high temperature, HEMC is a better option as the water retention agent and thickener by ensuring better work
performance and improving the strength of the mortar. In addition, the anti-sagging ability of HEMC is relatively better. It is more
recommended to be used in tile adhesive, thick plastering mortar, light render plaster and other mortars that have requirements for
anti-stiding.
specification |
E(2910) |
F(2906) |
K(2208) |
gelling |
58-64 |
62-68 |
68-90 |
methoxy |
27-30 |
27-30 |
19-24 |
hydroxyethyl |
7-12 |
4-7.5 |
4-12 |
viscosity |
3,5,6,15,50,4000,10000,30000,50000,7000 |
The performance of HEMC in dry mortar:
A. Excellent water retention can ffectively prevent the mortar from losing water so quickly as to lose its operabiliy, and avoid rapid
surface drying and cracking, and make the mortar have a longer opening time and adjustment time;
B. The thickening effect of HPMC can control the mortar to achieve the best consistency, improve the cohesion of the mortar, achieve
anti-sagging effect, improve operability, and greatly improve construction fficiency;
C. It can improve the bonding strength of the mortar, and it can ensure sufficient moisture and time to fully hydrate the cement,
thereby ensuring that the mortar has better bonding performance and strength even in a high temperature environment.