Friday, April 19, 2024
HomeAnswerHPMC is nontoxic powder

HPMC is nontoxic powder

Methyl-hydroxy-propyl-cellulose (MHPC) is a yellowish, odorless, and nontoxic powder. It is partially etherified with methyl groups, with few substituted hydroxyl-propyl groups. The viscosity of aqueous solutions remains constant within a pH range of 3.0–11.0. MHPC has the same characteristics as pure methyl-cellulose (MC) (Wüstenberg, 2014). The molecule of MHPC has a cellulose backbone made of β-d-glucose units with a (14) linkage. The three free-hydroxyl groups are partially etherified with methyl groups. The hydroxyl-propyl and methyl groups can be attached to both the cellulose's naturally occurring hydroxyl groups and newly formed hydroxyl-propyl groups through an ether bridge. The MHPC molecule is illustrated in Figure 11.8. The gravimetric content of methyl groups is 19–30%, and the content of hydroxyl-propyl groups is 3–12% (on a dry basis). The molecular weight is between 1.3 × 104 and 2 × 105 g mol−1, correlating with a DP of 70 to 1100 glucose monomers. MHPC with a DS of 1.5 to 2.0 is very soluble in cold water (0–30 °C) and polar organic solvents. The viscosity of the aqueous solution increases in the presence of sugars. MHPC in pure water gels at 58 °C and calcium sulfate at 10% decreases the gelation temperature to 4 °C. Increasing the polymer molecular weight (Patural et al., 2011) from 2.25 × 105 g mol−1 to 9.1 × 105 g mol−1 leads to an increase in both water retention and consistency coefficient in mortars. The water retention of MHPC was studied by Bülichen and Plank (2013) in cement pastes and a gypsum plaster utilizing the filter paper test. The water-retention capacity decreased significantly in the calcium sulfate system. Thus, higher dosages of MHPC were required in the gypsum plaster to attain water-retention values comparable to cement ones. It was determined that sulfate anions hinder the formation of colloidal associates, which presents the key process to achieving water retention. This observation explains the higher dosages required in CaSO4 systems. If you are looking for high quality, high purity, and cost-effective Hydroxypropyl methylcellulose, or if you require the latest price of Hydroxypropyl methylcellulose, please feel free to email contact mis-asia.

- Advertisment -

Most Popular

Recent Comments