Starch is one of the most prolific natural polymers, and is composed of amylose and amylopectin. Amylopectin molecules are much larger than amylase. Starch ethers are chemically modified from starch. Starch ether is one of the most cost-effective raw materials for the dry mortar industry. Its main function is adjusting the performance of the mortar in the state of fresh mixing. As a rheology modifier, it can prevent sag during mechanical construction and manual plastering, at the same time, can significantly improve the construction performance of the mortar and increase the output rate. Starch ether is effectively used in high quality tile adhesive to prevent tile slippage. It is also commonly used in self-leveling mortar and grouting material to prevent sedimentation, segregation etc.
High-purity potato starch is preferred for building. Starch molecular weight and the degree of etherification determine the consistency and workability of the starch ether applied to the mortar product. The fineness of the starch determines its dissolution rate in the water.
The modification methods of starch commonly used are: carboxymethylation (CM), and hydroxyalkyl (HP) and cross-linking (CL) methods. Amylase gains rapid swelling, smooth, as well as resistance to alkali, temperature stability, high-viscosity and shear stability through different chemical modifications.
The particle size can change on the solubility of starch ether. The smaller the particle size, the faster the dissolution rate of starch ether is, so is the thickening effect. Through physical modification, starch ether can be applied more broadly.
The function of starch ether in mortar is mainly related to its special branched chain molecular structure, modification degree and particle size adjustment. Dissolving in water to form a network structure, absorb cement particles and interact with other solid particles, it forms a viscosity structure. Due to the structural characteristics and different chemical modification of starch ether coolness, the properties of freshly mixed mortar can be improved and adjusted to different degrees.
Starch ether can be used as thickener for fresh mixed mortar and improve the wetness and viscosity. As a rheological modifier, it can prevent the droop during mechanical and manual plastering, improve its construction property and increase the pumping property of spray mortar. It can also be used for the preparation of the high-quality ceramic tile adhesives, effectively prevent the slippery tile; As a stabilizer, it can be used in self-leveling mortar and grouting material with high fluidity to prevent settlement and segregation. In addition, starch can also improve the apparent state of wet mortar, increase the yield of mortar.