What factors will affect the viscosity of hydroxypropyl methylcellulose?

For the application of wet mortar, hydroxypropyl methylcellulose has good thickening properties, can significantly increase the bonding ability between wet mortar and the base layer, and can also improve the anti-sag performance of mortar, so it is widely used in plastering Mortar, external wall insulation system and brick bonding mortar.

For the thickening effect of cellulose ether, it can also increase the homogeneity and anti-dispersion ability of freshly mixed cement-based materials, and can also prevent the problems of delamination, segregation and bleeding in mortar and concrete. It can be applied to Fiber-reinforced concrete, underwater concrete and self-compacting concrete.

Hydroxypropyl methylcellulose can increase the viscous performance of cement-based materials. This performance mainly comes from the viscosity of cellulose ether solution. Generally, the numerical index of viscosity is used to judge the viscosity of cellulose ether solution, while cellulose The viscosity of ether usually mainly refers to a certain concentration of cellulose ether solution, usually 2%, at a specified temperature, such as 20 degrees and a rotation rate, using a specified measuring instrument, such as a rotational viscometer. Viscosity value.

Viscosity is one of the important parameters to evaluate the performance of cellulose ether. The higher the viscosity of hydroxypropyl methylcellulose solution, the better the viscosity of cement-based materials, and the better the adhesion performance to the substrate. At the same time, it has The anti-sagging ability and anti-dispersion ability are stronger, but if its viscosity is too high, it will affect the flow performance and operability of cement-based materials.

What factors will affect the viscosity of hydroxypropyl methylcellulose? Mainly depends on the following reasons.

1. The higher the degree of polymerization of cellulose ether of hydroxypropyl methylcellulose, the larger its molecular weight, resulting in higher viscosity of its aqueous solution.

2. If the amount or concentration of cellulose ether is higher, the viscosity of its aqueous solution will be higher. However, care should be taken to select an appropriate amount of cellulose ether when using it, mainly to avoid excessively high amount of cellulose ether. It will affect the performance of mortar and concrete.

3. Like most liquids, the viscosity of cellulose ether solution will decrease with the increase of temperature, and the higher the concentration of cellulose ether, the lower the temperature. The greater the impact.

4. Cellulose ether solution is usually a pseudoplastic, which has the characteristics of shear thinning. The greater the shear rate during the test, the smaller the viscosity.

The cohesiveness of mortar will be reduced due to the action of external force, which is also conducive to the scraping construction of mortar, resulting in good cohesiveness and workability of mortar at the same time. However, if the cellulose ether solution has a higher concentration When the viscosity is low and the viscosity is small, it will show the characteristics of Newtonian fluid. When the concentration increases, the solution will gradually show the characteristics of pseudoplastic fluid, and if the concentration is higher, the pseudoplasticity will be more obvious.