The Difference Between HPMC(Hydroxypropyl Methyl Cellulose) & MHEC(Methyl Hydroxyethyl Cellulose)
1.The similar performances between HPMC and MHEC in construction chemicals:
Used as thickener, dispersant, water retention agent and air-entraining agent etc. Mainly used in cement and gypsum based dry mix mortar to increase bond strength, workability, and water retention. Reduce water loss on concrete surface, preventing cracks and increase scrape area. It is widely used in wall plaster and tile adhesive products
In paints, as a protective colloid, HPMC and MHEC can be used in the polymerization of vinyl acetate emulsion to improve the stability of the polymerization system in a wide pH range. Use pigments, fillers and other additives in finished product manufacturing to evenly disperse, stabilize and provide thickening effect.
2.The difference between HPMC and MHEC: Thermal Stability
Thermal stability of HPMC and MHEC is affected by their gel temperature.
In general, the gel temperature of HPMC is around 60℃-75℃ depending on its group content and different production technique. Due to the characteristics of MHEC group, it has a higher gel temperature, usually > 80℃. Therefore its stability under high temperature is better that HPMC. In practical construction, in the hot construction environment in summer, the water holding capacity of MHEC with the same viscosity and dosage is better than that of HPMC. Especially in the Southeast Asian countries and India, mortar will sometimes be constructed at high temperature. Cellulose ether with low gel temperature will lose its thickening and water retention at high temperature, thereby accelerating the hardening of mortar, and affects the construction.
On the other hand, because there are more hydrophilic groups in the structure of MHEC, it has better hydrophilicity. The water retention rate of MHEC in mortar is a little higher than HPMC at the same dosage of products with the same viscosity.