The role of hydroxypropyl starch ether in mortar

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Introduction to Starch Ether

The more common and commonly used starches are potato starch, tapioca starch, corn starch, wheat starch, and cereal starch with higher fat and protein content. Root crop starches such as potato and tapioca starch are more pure.

Starch is a polysaccharide macromolecular compound composed of glucose. There are two types of molecules, linear and branched, called amylose (content 20%) and amylopectin (content about 80%). In order to improve the use properties of starch in building materials, it can be modified by physical and chemical methods to make its properties more suitable for the needs of building materials for different purposes. Hydroxypropyl starch ether

The role of starch ether in mortar

For the current trend of increasing tile area, adding starch ether can improve the slip resistance of tile adhesive.

extended opening hours

For tile adhesives, it can meet the requirements of special tile adhesives (Class E, 20min extended to 30min to reach 0.5MPa) that extend the opening time.

Improved surface properties

Starch ether can make the surface of gypsum base and cement mortar smooth, easy to apply, and has good decorative effect. It is very meaningful for plastering mortar and thin layer decorative mortar such as putty.

Mechanism of action of starch ether

When starch ether dissolves in water, it will be evenly dispersed in the cement mortar system. Since the starch ether molecule has a network structure and is negatively charged, it will absorb positively charged cement particles and serve as a transition bridge to connect the cement, thus giving The larger yield value of the slurry can improve the anti-sag or anti-slip effect.

The difference between starch ether and cellulose ether

(1) Starch ether can effectively improve the anti-sag and anti-slip performance of mortar, while cellulose ether usually can only improve the viscosity and water retention of the system but cannot improve the anti-sag and anti-slip performance.

(2) thickening and viscosity

Generally, the viscosity of cellulose ether is about tens of thousands, while the viscosity of starch ether is several hundred to several thousand, but this does not mean that the thickening property of starch ether to mortar is not as good as that of cellulose ether, and the thickening mechanism of the two is different.

(3) Compared with cellulose, starch ether can significantly increase the initial yield value of tile adhesive, thereby improving the anti-slip performance.

(4) Air entrainment

Cellulose ether has a strong air-entraining property, while starch ether has no air-entraining property.

(5) Cellulose ether molecular structure

Although both starch and cellulose are composed of glucose molecules, their composition methods are different. All the glucose molecules in starch are arranged in the same direction, while cellulose is just the opposite. Every adjacent The orientation of glucose molecules is opposite, and this structural difference also determines the difference in the properties of cellulose and starch.

Conclusion: When cellulose ether and starch ether are used in combination, a good synergistic effect can occur. Experiments have proved that using starch ether to replace 20%-30% of cellulose ether in mortar can not reduce the water retention capacity of the mortar system, and can effectively improve the anti-sag and anti-slip ability.