Hydroxypropyl methylcellulose (HPMC) is a non-ionic cellulose ether widely used in building materials, medicine, food, cosmetics and other industrial fields. It has many excellent physical properties, which make it perform well in various applications.
1. Appearance and solubility
HPMC is usually a white or off-white powder, odorless, tasteless and non-toxic. It can be dissolved in cold water and certain organic solvents (such as mixed solvents such as ethanol/water and acetone/water), but is insoluble in pure ethanol, ether and chloroform. Due to its non-ionic nature, it will not undergo electrolytic reaction in aqueous solution and will not be significantly affected by pH value.
2. Viscosity and rheology
HPMC aqueous solution has good thickening and thixotropy. Different types of AnxinCel®HPMC have different viscosities, and the common range is 5 to 100000 mPa·s (2% aqueous solution, 20°C). Its solution exhibits pseudoplasticity, that is, shear thinning phenomenon, and is suitable for application scenarios such as coatings, slurries, adhesives, etc. that require good rheology.
3. Thermal gelation
When HPMC is heated in water, the transparency of the solution decreases and gel is formed at a certain temperature. After cooling, the gel state will return to the solution state. Different types of HPMC have different gel temperatures, generally between 50 and 75°C. This property is particularly important in applications such as building mortar and pharmaceutical capsules.
4. Surface activity
Because HPMC molecules contain hydrophilic and hydrophobic groups, they show certain surface activity and can play an emulsifying, dispersing and stabilizing role. For example, in coatings and emulsions, HPMC can improve the stability of the emulsion and prevent the sedimentation of pigment particles.
5. Hygroscopicity
HPMC has a certain hygroscopicity and can absorb moisture in a humid environment. Therefore, in some applications, attention should be paid to packaging sealing to prevent moisture absorption and agglomeration.
6. Film-forming property
HPMC can form a tough and transparent film, which is widely used in food, medicine (such as coating agents) and coatings. For example, in the pharmaceutical industry, HPMC film can be used as a tablet coating to improve drug stability and control release.
7. Biocompatibility and safety
HPMC is non-toxic and harmless, and can be safely metabolized by the human body, so it is widely used in the fields of medicine and food. As a pharmaceutical excipient, it is usually used to produce sustained-release tablets, capsule shells, etc.
8. pH stability of solution
HPMC is stable in the pH range of 3 to 11, and is not easily degraded or precipitated by acid and alkali, so it can be used in a variety of chemical systems, such as building materials, daily chemical products and pharmaceutical formulations.
9. Salt resistance
HPMC solution is relatively stable to inorganic salts and is not easily precipitated or ineffective due to changes in ion concentration, which enables it to maintain good performance in some salt-containing systems (such as cement mortar).
10. Thermal stability
AnxinCel®HPMC has good stability in high temperature environments, but it may degrade or discolor when exposed to high temperatures for a long time. It can still maintain good performance within a certain temperature range (usually below 200°C), so it is suitable for high-temperature processing applications.
11. Chemical stability
HPMC is relatively stable to light, oxidants and common chemicals, and is not easily affected by external chemical factors. Therefore, it can be used in products that require long-term storage, such as building materials and medicines.
Hydroxypropyl methylcellulose is widely used in many industries due to its excellent solubility, thickening, thermal gelation, film-forming properties and chemical stability. In the construction industry, it can be used as a cement mortar thickener; in the pharmaceutical industry, it can be used as a pharmaceutical excipient; in the food industry, it is a common food additive. It is these unique physical properties that make HPMC an important functional polymer material.
Post time: Feb-10-2025