Exploring MHEC Insights for Enhanced Academic Collaboration and Innovation Strategies
In the past, attempts have been made to clarify the working mechanism of methyl cellulose (MC). Early works from Schweizer et al. present the effect of cellulose ethers on water retention and rheology of cementitious mortars and gypsum-based machinery plasters [15], [16]. They demonstrate that adsorption of methyl cellulose is clearly dependent on the degree of substitution (DS). At DS values of > 1.6 which are typical for MC products used in the building industry, only a minor amount (~ 20%) of the MC powder adsorbs. In a very skillful experiment the authors show that during the drying process of a gypsum-based render, MC migrates with the water to the surface of the render and is not retained by adsorption. Thus, they conclude that MC does not adsorb on the binder or its hydrates. Similar observations have been made by Yammamuro et al. [17].
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.