The advanges of HPMC & MHEC in dry mix mortar products
November 22nd 2024Redispersible polymer powder, as one of the most important additives in dry-mixed mortar, has been widely used in the construction field. Its invention and appearance have greatly contributed to the promotion and application of dry-mixed mortar. SLEO shows you the great functions of RDP products.
The most widely used RD powders are vinyl vinyl acetate – ethylene – ethylene (VCAE) and vinyl acetate – ethylene tertiary carbonate (VEOVA). Improving the bond tensile strength of cementitious mortars with various substrates is the most important property of vinyl copolymers, especially their ability to withstand large changes in ambient temperature. In addition, it facilitates the development of long-term tensile bond strength of cementitious mortars. After two and a half years of storage in air, the bond tensile strength of the modified cementitious mortar was still increasing, while the tensile strength of the ordinary cementitious mortar was still increasing.
Foreign studies have shown that three RDP dry-mixed modified cement mortars, polyvinyl acetate, styrene/acrylic acid copolymer and ethylene/vinyl chloride/ethylene laurate copolymer, have stable bond strength, flexural strength and compressive strength of cementitious mortars even after a long time. The appearance of the polymer cementitious mortar does not change under dry indoor and outdoor conditions. The secondary toughening of the polymer in the mortar plays an important role especially in the pores and defects of the substrate. RDP is not dispersed twice and is not washed out from the cementitious mortar.
Cement and redispersible latex powder rdp have a synergistic effect. As an inorganic cementitious material, cement plays a major role in the compressive strength; the redispersible polymer powder, as an organic cementitious material, acts as a toughening agent to improve the internal and interfacial bond strength of cementitious mortars.
If polyvinyl acetate is often used to improve the fracture toughness, impermeability and bond strength of cement mortars with different matrix materials, then styrene/acrylic acid copolymers are more important to improve the flexibility of cement mortars. Cement can maintain the stability of mechanical properties such as compressive strength, while the redispersible polymer powder can improve the internal tensile strength and interfacial bond tensile strength of mortar. The effect of water-cement ratio is less than the effect of cement dosing. Cement can maintain the stability of mechanical properties such as compressive strength, while redispersible polymer powder can improve the internal tensile strength and interfacial bond tensile strength of mortar.
The technical difficulty in producing RDP is to convert the high viscosity copolymer liquid into redispersible and redispersible powder at room temperature by high temperature, high pressure, spray drying and surface treatment to produce RDP with the same particle size distribution as the original emulsion. However, not all copolymer emulsions can be converted into redispersible polymer powders.
RDP as a new generation powdered adhesive has been widely used in plastering mortar, interface agent, interior and exterior wall putty, tile adhesive, caulk, repair mortar, self-leveling mortar, dry powder coating, colored concrete art flooring, factory hard flooring, moisturizing system and other construction materials. If you need to buy these products, please contact us today, and we’ll answer you asap, hope we can have a good cooperation.
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