Regarding dispersible polymer powder

In order to improve the brittleness and high elastic modulus of traditional cement mortar, redispersible emulsion powder is usually added as an additive. It can give cement mortar better flexibility and tensile bond strength to resist and delay the occurrence of cement mortar cracks. 

Due to the formation of an interpenetrating network structure between the polymer and the mortar, a continuous polymer film is formed in the pores, which strengthens the bond between the aggregates and blocks part of the pores in the mortar. Therefore, the performance of the modified mortar after hardening is greatly improved compared with that of cement mortar.

The emulsion powder is polymerized under high temperature, high pressure, and spray drying with various active reinforcing powders, which can significantly improve the bonding ability and tensile strength of mortar. It has good anti-sagging, water retention, thickening, and construction performance, as well as outstanding water resistance, freeze-thaw resistance, and heat aging resistance. It is easy to mix and convenient to use. The emulsion powder has excellent compatibility with cement and can completely dissolve in cement-based dry-mixed mortar paste. After curing, it does not reduce the strength of cement while maintaining bonding, film-forming, and flexibility.

It also has good weather resistance, stability, bonding performance, and crack resistance. After drying, it can effectively prevent the erosion of acidic air on the wall and is not prone to pulverization and deliquescence when wet. Adding redispersible emulsion powder to putty powder and mortar can increase their strength and greatly help improve hardness. It has excellent waterproof performance, good bonding strength, and can increase the elasticity of mortar with a long open time. It also gives mortar excellent alkali resistance and can improve the adhesion/bonding, flexural strength, wear resistance, and workability of mortar. In flexible anti-crack mortar, it has stronger flexibility.

In theory, emulsion powders with a glass transition temperature below 5°C are relatively flexible and are mainly used in exterior wall insulation mortar. Emulsion powders with a glass transition temperature above 10°C are mainly used in adhesives and self-leveling mortar.

Under high emulsion powder content, the polymer phase in the cured mortar gradually exceeds the phase of inorganic hydration products, and the mortar undergoes a qualitative change, becoming an elastomer. Meanwhile, the hydration products of cement become a kind of "filler". The membrane formed by the redispersible emulsion powder distributed on the interface plays another crucial role, which is to enhance the adhesion to the contacted materials. 

This is especially important for some difficult-to-bond surfaces, such as extremely low water-absorbing or non-water-absorbing surfaces (such as smooth concrete and cement material surfaces, steel plates, homogeneous bricks, vitrified tiles, etc.) and organic material surfaces (such as EPS boards, plastics, etc.). Because inorganic adhesives bond materials through the principle of mechanical embedding, that is, the hydraulic slurry penetrates into the gaps of other materials and gradually solidifies. 

For the above difficult-to-bond surfaces, since it cannot effectively penetrate into the material interior to form a good mechanical embedding, the mortar with only inorganic adhesives cannot effectively bond with it. Electron microscope observations also well prove this point. However, the bonding mechanism of polymers is different. Polymers bond to other material surfaces through intermolecular forces rather than relying on surface porosity (although a rough surface and increased contact area will improve adhesion). This is more evident in the case of organic substrates, and electron microscope observations also prove the superiority of its adhesion.

The emulsion powder changes the consistency and smoothness of the system in a wet mixing state. Adding emulsion powder improves cohesion, providing bonding force for a smooth and dense surface after drying. It improves the interface interaction between sand, stone, and pores. When the amount of addition is ensured, it forms a film rich in the interface, making tile adhesive flexible, reducing the elastic modulus, and greatly absorbing thermal deformation stress. It also has waterproofness when exposed to water later, buffering temperature and material deformation inconsistencies. The flexibility and rigidity of the emulsion powder can generally be judged according to the glass transition temperature. Those with a glass transition temperature below 0°C tend to be flexible. The type of emulsion powder needed in mortar is generally determined according to the performance characteristics of the product. Selecting the right type of emulsion powder can provide qualitative help to the product, which is the charm of redispersible emulsion powder.

Name:Charles Deng  

E-mail:charles.deng@jtdf-rdp.com

Whatsapp:(86)150-6919-9138