Introduction to RDP-Redispersible Polymer Powder

Redispersible polymer powder (RDP) is a polymer based powder used in various applications in the construction industry. RDP was obtained by spray drying of polymer emulsions. It is widely used in cement systems to improve the properties of mortars such as adhesion, water resistance and flexural strength.

RDP is composed of a variety of polymers, including vinyl acetate-ethylene (VAE), styrene-butadiene (SB), ethylene-vinyl chloride (EVC), and polyvinyl alcohol (PVA). These polymers are designed to be compatible with different types of binders such as cement, lime and gypsum. They are used in different types of applications including tile adhesives, self-leveling compounds, waterproofing membranes and exterior insulation and finishing systems (EIFS).

The manufacturing process of RDP consists of three main stages: polymerization, emulsification and spray drying. In the polymerization stage, monomers are polymerized under specific conditions, such as temperature, pressure and reaction time. The resulting polymer dispersion is stabilized with surfactants to prevent particle agglomeration. In the emulsification stage, the polymer dispersion is further processed to form an emulsion, which is then spray dried to obtain RDP. During spray drying, water evaporates from the emulsion droplets, forming polymer particles. The resulting powder is then collected and packaged for shipping.

The properties of RDP depend on several factors such as the type of polymer, particle size and chemical composition. The most commonly used polymer for RDP is VAE, which has excellent adhesion and water resistance. The particle size of RDP can vary from a few microns to a few millimeters, depending on the application. The chemical composition of RDP can also vary depending on the desired properties. For example, RDPs can contain additional additives such as plasticizers, dispersants and thickeners to enhance their properties.

RDP has many advantages over other types of polymers used in construction. One of the main advantages is its ability to redisperse in water. This means that RDP can be mixed with water to form a stable emulsion, which can then be used in a variety of applications. The redispersibility of RDP depends on its chemical composition and particle size. RDP particles are designed to be water compatible and disperse quickly when mixed with water.

Another advantage of RDP is its ability to improve the performance of cement systems. RDP can improve the adhesion between mortar and substrate, reduce shrinkage and increase the strength of mortar. It also improves the water resistance of the mortar, preventing water penetration and reducing the risk of weathering.