Factors Affecting the Viscosity of Hydroxypropyl Methyl Cellulose
Hydroxypropyl methyl cellulose (HPMC) is a nonionic water-soluble mixed ether of cellulose. Appearance is white to light yellow powder or granules, tasteless, odorless, non-toxic, chemically stable product, soluble in water to form a smooth and transparent viscous solution.
1. The relationship between viscosity and concentration
The viscosity of hydroxypropyl methylcellulose increases with the concentration of the product in the aqueous solution. Even small changes in concentration can cause large changes in viscosity. With the increase of the nominal viscosity of hydroxypropyl methylcellulose, the influence of the concentration change on the solution viscosity becomes more and more obvious.
2. The relationship between viscosity and temperature
The viscosity of HPMC solution is greatly affected by temperature. As the temperature increases, the viscosity of the solution decreases.
3. The relationship between viscosity and shear rate
The HPMC aqueous solution has the characteristic of shear thinning. Hydroxypropyl methylcellulose with different nominal viscosity is prepared into a 2% aqueous solution. And its viscosity at different shear rates is measured respectively. At low shear rates, the HPMC solution There is no obvious change in viscosity. With the increase of shear rate, the viscosity of hydroxypropyl methylcellulose solution with higher nominal viscosity decreases more obviously. While the solution with low viscosity has no obvious decrease.
4. The relationship with the degree of polymerization
When other parameters remain unchanged, the viscosity of HPMC solution is proportional to the degree of polymerization (DP) or molecular weight or molecular chain length, and increases with the increase of degree of polymerization. This effect is more pronounced at low degrees of polymerization than at high degrees of polymerization.
If the hydroxypropyl methylcellulose aqueous solution needs to be stored for a long time. It is recommended to add a small amount of antifungal agent so that the viscosity does not change significantly. When choosing antifungal agents, preservatives or fungicides, you should choose products that are not toxic to the human body, stable in nature, and odorless.
Landcel can produce 300-70000cps HPMC products. Mainly used for construction and daily chemical addition, welcome your consultation.