Hydroxypropyl MethylCellulose has thermal gelation properties, so after heating the aqueous solution will precipitate and form gels, and dissolve again after cooling. So the gelation is reversible products of different specifications have different gelling temperatures.
As the methoxyl content decreases, the gel point of HydroxyPropyl MethylCellulose rises; the water solubility decreases, and the surface activity will accordingly reduce.
When HPMC is used in building materials, usually we prefer HPMC with a high gel temperature point, this is because in practical applications, mortar is often used under high-temperature conditions (above 35°C), and the temperature of the substrate is also very high. Due to the dual effects of weather and substrate, the water holding rate of the mortar is reduced, resulting in rapid water loss and affecting the hydration of cement. The strength of mortar decreases, which affects construction performance and crack resistance. In this case, cellulose ethers with good water retention properties should be selected at high temperatures.
