Hydroxypropyl methylcellulose, 28-30% methoxyl, 7-12% hydroxypropyl

The specifications “28-30% methoxyl” and “7-12% hydroxypropyl” refer to the degree of substitution in Hydroxypropyl Methylcellulose (HPMC). These values indicate the extent to which the original cellulose polymer has been chemically modified with methoxyl and hydroxypropyl groups.

1. 28-30% Methoxyl:
   • This indicates that, on average, 28-30% of the original hydroxyl groups on the cellulose molecule have been substituted with methoxyl groups. Methoxyl groups (-OCH3) are introduced to increase the hydrophobicity of the polymer.
2. 7-12% Hydroxypropyl:
   • This signifies that, on average, 7-12% of the original hydroxyl groups on the cellulose molecule have been substituted with hydroxypropyl groups. Hydroxypropyl groups (-OCH2CHOHCH3) are introduced to enhance the water solubility and modify other physical and chemical properties of the polymer.

The degree of substitution influences the properties of HPMC and its performance in various applications. For example:

• A higher methoxyl content generally increases the polymer’s hydrophobicity, affecting its water solubility and other properties.
• A higher hydroxypropyl content can enhance the water solubility and film-forming properties of HPMC.

These specifications are crucial in tailoring HPMC to meet specific requirements in different industries. For instance, in the pharmaceutical industry, the choice of HPMC grade with specific degrees of substitution can affect drug release profiles in tablet formulations. In the construction industry, it can impact the water retention and adhesion properties of cement-based products.

Manufacturers produce various grades of HPMC with different degrees of substitution to meet the diverse needs of different applications. When using HPMC in formulations, it’s important for formulators to consider the specific grade of HPMC that aligns with the desired properties and performance characteristics for the intended application.