Solubility of HPMC in Organic Solvents
October 29th 2024
Hydroxypropyl Methylcellulose (HPMC) is a hydrophilic (water soluble), biodegradable, and biocompatible polymer with higher organic solubility and thermoplasticity than its other methylcellulose counterparts. HPMC has a wide range of applications in drug delivery, dyes and paints, cosmetics, adhesives, coatings, agriculture, textiles, and construction. In construction materials, hydroxypropyl methylcellulose is used as a dispersant, thickener and binder. Hydroxypropyl methylcellulose has unique advantages in the application of construction materials, from mixing to dispersing to construction, as described below.
Water holding capacity
HPMC enhances the plastic viscosity and cohesion of mortar, reducing the ability of water migration and loss, thus improving the water retention of mortar. The addition of only a small amount of hydroxypropyl methylcellulose can significantly increase the water retention of a mortar.
At an addition level of 0.002%, the water retention rate increases from 83% to 88%; 0.02% for the former and up to 97% for the latter. At the same time, low levels of Hydroxypropyl Methylcellulose additions also significantly reduced the delamination and water retention of the mortar. This indicates that Hydroxypropyl Methylcellulose not only enhances the water retention of the mortar, but also significantly improves the bonding of the mortar, which is very beneficial for the homogeneity of the mortar construction quality.
This is one of the most important Hydroxypropyl Methylcellulose effects. Hydroxypropyl Methylcellulose for construction prevents water penetration into walls. The right amount of water left in the mortar helps to give the cement a longer hydration time. Water retention is proportional to the viscosity of the cellulose ether solution in the mortar; the higher the viscosity, the better the water retention; once the water molecules increase, the water holding capacity decreases. This is because for the same amount of hydroxypropyl methylcellulose solution for construction, an increase in water means a decrease in viscosity. The increase in water holding capacity leads to longer maintenance times for the mortar during construction.
Hydroxypropylmethylcellulose is used in cement mortars to increase their adhesion, reduce flocculation, increase viscosity, shrinkage and water retention, reduce water loss from the concrete surface, increase strength, prevent the occurrence of cracks and the weathering effect of water-soluble salts.
Ease of handling
Dry mix formulations containing hydroxypropyl methylcellulose can be easily mixed with water to obtain the required consistency quickly and the cellulose ether dissolves quickly without agglomeration, so the application of hydroxypropyl methylcellulose can improve the compatibility of mortar.
Lubricating ability
All air-entraining agents act as wetting agents, as they reduce surface tension and then help disperse the fines in the mortar when mixed with water, allowing the solid particles to be effectively suspended and making the mixture smoother and more homogeneous.
Anti-sagging properties
A good anti-sag mortar means that there is no risk of sagging or downward flow during the construction of thick layers. Construction-specific hydroxypropyl methylcellulose offers improved sagging resistance, especially with the newly developed construction-specific hydroxypropyl methylcellulose, which provides better sagging resistance, helps prevent vertical flow of mortar, grout and tiles, prolongs cooling time and improves efficiency.
Anti-cracking properties
The high bubble content leads to better mortar yield and compatibility and reduces the formation of cracks. At the same time, the strength value is reduced and “liquefaction” occurs. The air bubble content is usually dependent on the mixing time and by increasing the air content in the mortar, the crack shrinkage and crack strength of the mortar and board sealer is improved, greatly reducing the likelihood of cracking. Hydroxypropyl methylcellulose products are widely used to improve the performance of water-hardened building materials such as cement, tiles and gypsum.
Environmentally friendly
Hydroxypropylmethylcellulose also meets environmental requirements. In dry-mix mortars, it helps to avoid unstable performance due to mix formation, pollution of the surrounding environment, poor construction conditions and low labour efficiency. Tile adhesives and interior and exterior wall putties were previously usually used as binders. Therefore, from an environmental point of view, the application of cellulose ethers, such as hydroxypropyl methylcellulose, may be preferable.
With the development of the construction market, in particular the increased mechanisation of construction and the increased quality requirements of construction, the consumption of HPMC in the construction sector will continue to increase.
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