High-Performance HPMC for Industrial Applications and Its Benefits in Construction and Coatings
1. The different water retention performance makes the mortar open for a longer time, with large area construction, long service life in the bucket, batch mixing and batch use.
2. The good water retention property makes the cement in the mortar fully hydrated and effectively improves the bonding performance of the mortar.
3. The mortar has different water retention performance, which makes it difficult to produce segregation and bleeding, and improves the workability and workability of the mortar.
The working mechanism of methyl hydroxyethyl cellulose, MHEC (Mw = 2.5 · 105 g/mol, DSmethyl = 1.81, MShydroxyethyl = 0.15) as water retention agent in cement was investigated. First, the hydrocolloid was characterized and its performance as non-ionic water retention agent was determined employing the filter paper test. Also, water sorption and swelling of individual MHEC fibers under conditions of different humidities were monitored by ESEM imaging. Second, its working mechanism was established. It was found that at low dosages, MHEC achieves water retention by intramolecular sorption of water and concomitant swelling while at higher dosages, MHEC molecules agglomerate into large hydrocolloidal microgel particles (d > 1 μm) which effectively plug the pores in the mortar matrix. MHEC association was evidenced by an exponential increase in solution viscosity as concentration rises, a strong increase in the hydrodynamic diameter of solved MHEC molecules, and a noticeable reduction of surface tension.