Mowiol 5-88

Polyvinyl alcohol (PVA), an indispensable water-soluble polymer material, is used in a wide range of fields, including construction, textiles, papermaking, and chemicals. Among the many PVA specifications, mesh size, or particle fineness, is a key factor in determining processing efficiency and final product quality.   1. Mesh Size Basics: A Measurement of Particle Size Mesh size is a unit of measurement for powder particle fineness. It refers to the number of holes in a sieve per inch. The smaller the mesh size, the larger (coarser) the particles. Mesh size and dissolution rate: The dissolution process of a powder begins with the wetting and penetration of the particle surface by water molecules. The finer the particle size (the larger the mesh size), the greater its specific surface area. A larger specific surface area means that water molecules can contact more PVA molecular chains, significantly accelerating wetting, swelling, and disentanglement, ultimately increasing dissolution rate. Mesh size and dispersion uniformity: Fine particles are more easily dispersed in liquid or solid mixtures. When coarse particles (such as 20 mesh) are added to water, they are more likely to settle or clump due to density differences, forming "fish eyes" that are difficult to dissolve. Mesh Size and Dust Density: The finer the particle size, the lower the critical velocity at which it becomes suspended in air, resulting in higher dust levels. 20 mesh PVA produces low dust, while 200 mesh PVA requires strict dust control measures.   2. Introduction and Application of PVA Specifications of Different Mesh Sizes Mesh Size  20 mesh(Polyvinyl Alcohol 0588) 120 mesh (PVA 088-05S) 200 mesh (POVAL 22-88 S2) Photo Bulk Density Relatively high Medium Relatively low (fluffy powder) Key Features The largest particles have the lowest surface area. This dissolution process is the slowest, but dust generation during operation is minimal; it is also known as a "low-dust" or "dust-free" grade. This medium-sized particle size is the most commonly used grade in industry. It strikes a good balance between dissolution efficiency, ease of operation, and cost. The extremely fine particles and maximum surface area ensure the fastest dissolution and the best dispersibility. Applications Dry-mix mortar for construction: Coarse-grained PVA, as a binder, is less likely to form high-viscosity clumps during initial mixing, allowing for better dispersion in other components (such as cement and sand). It also produces minimal dust, improving the on-site construction environment.   Specialized slow-release adhesives: In certain specialized construction mortars or adhesives, PVA needs to dissolve slowly to provide lasting adhesion.   Preventing rapid thickening: Suitable for formulations that require prolonged mixing and where rapid thickening of the solution is undesirable. Conventional adhesives: Used in the manufacture of common water-based adhesives such as wood glue and paper glue.   Textile sizing agents: Prepare sizings at standard temperatures and times to meet the sizing requirements of most textiles.   Emulsion polymerization protective colloids: Serves as stabilizers and protective colloids in the polymerization of emulsions (such as VAE and acrylic emulsions). They provide a sufficiently rapid dissolution rate without excessively increasing system viscosity, ensuring stability and particle size distribution during emulsion polymerization. High-end water-based coatings: Suitable for high-end paints and putty powders that require extremely high dispersibility and a minimum of residual particles.   Fast Preparation/Low-Temperature Dissolution: Fine powder ensures rapid and thorough dissolution of PVA at low temperatures or under limited stirring capacity.   Water-Soluble Film: Used in the production of water-soluble packaging films requiring high transparency and good solubility, such as laundry bags and pesticide packaging.   Pharmaceutical/Cosmetic Excipients: Used in certain fine chemical applications requiring high precision.   3. How to Make the Best Choice? Choosing the right mesh size for PVA is essentially a trade-off between production efficiency, environmental safety, and product performance: For those seeking dissolution speed and product fineness (e.g., coatings and films): 200 mesh is preferred. For those seeking versatility, balanced performance, and moderate cost (e.g., conventional adhesives): 120 mesh is preferred(PVA 088-50S). For those emphasizing operational safety, low dust generation (e.g., large-volume batching), or specific sustained-release requirements: 20 mesh is preferred(Poval 217).   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

VAE emulsion are water-based and good for the environment. They're used a lot as binders in strong glues. As the tech gets better and the emulsion market grows, people want more VAE emulsions, mainly those with a lot of ethylene. These high-ethylene VAE emulsions are great at resisting water and alkali, so they're becoming more popular. How much ethylene is in VAE emulsions depends on things like pressure, temperature, time, how much initiator is used, the type and amount of emulsifier, and how the VAE is added. Lately, the market wants VAE emulsions that bind water really well. This paper looks at how the amount of ethylene in VAE emulsions affects them. We used different molecular weights of polyvinyl alcohols (PVA Polyvinyl Alcohol 088-20 and PVA Polyvinyl Alcohol 0588) as protective colloids, and a special PVA was used as part of the protective colloid to see how these colloids change the VAE emulsion properties.   1.Effect of Emulsifier Content on Emulsion Properties In emulsion polymerization systems, the type and concentration of the emulsifier, as well as various factors that may influence the emulsification effect of the emulsifier, directly affect the stability of the polymerization reaction and, ultimately, the properties of the emulsion. As seen in Table 3 and Figure 2, a rise in emulsifier content leads to a higher conversion rate but a lower gel fraction. If the emulsifier surpasses 4%, the conversion rate drops, suggesting the substance is not chemically stable. Therefore, the optimal emulsifier content for this experiment is 4%.   2. Effect of Initiator Content on Molecular Weight and Emulsion Viscosity The initiator is the most important component in the entire VAE emulsion formulation. It decomposes and releases free radicals, which are the basis for emulsion polymerization. Figure 3 shows that with increasing initiator content, both molecular weight and viscosity show an upward trend, with the optimal initiator dosage being 2.5%.   3. Effect of Reaction Temperature on Emulsion Reaction Table 4 shows that with increasing reaction temperature, the reaction rate accelerates, the residual monomer content decreases, and the amount of aggregates increases. Raising the reaction temperature speeds up how fast the initiator breaks down, making more free radicals and boosting the number of spots where reactions can happen. At the same time, a higher temperature makes latex particles move around more randomly, which means they bump into each other and join together more often. Because of these things, the emulsion becomes less stable and might even turn into a gel or separate. Therefore, the initial reaction temperature is determined to be 65°C, and the later reaction temperature is 70°C to 85°C.   4. Effect of Polymerization Reaction Pressure on Ethylene Content, Solids Content, and Viscosity Figure 4 shows that increasing the reaction pressure within a certain range gradually increases the ethylene content of the VAE emulsion and decreases the glass transition temperature of the product. At a reaction pressure of 7.5 MPa, the ethylene content reaches 21%, and the glass transition temperature lowers to -4°C. As shown in Figure 5, under the best reaction conditions, the solid content goes up as the polymerization pressure increases, but the change is small, staying within (56 ± 0.5)%. The emulsion viscosity first goes up and then down as the polymerization pressure increases, peaking at 3200 mP·s at a polymerization pressure of 6 MPa before going down. This indicates that a certain pressure can facilitate polymerization and increase the emulsion viscosity.   5. Effect of Modified PVA as a Protective Colloid on VAE Emulsion Properties To increase how well VAE emulsions resist water, a PVA, changed to include water-repelling groups, was used to take the place of some of the PVA1788 protective colloid. Table 5 shows how varying amounts of the modified PVA (from 10% to 50% of the total protective colloid) change the VAE emulsions' stability, thickness, and water resistance. The data in Table 5 shows that as the amount of modified PVA goes up, the emulsion stays stable without separating, suggesting the modified PVA doesn't really impact the system's stability. Based on Figure 6, the emulsion gets thicker as the modified PVA content rises, peaking at 4000 mPa·s when the modified PVA makes up 5% of the mixture.   6. VAE Emulsions with Different Ethylene Contents and Properties We made different VAE emulsions by testing how different reaction conditions change the emulsion's properties. These emulsions had different amounts of ethylene, glass transition temperatures, and leftover VAc.   We found that starting the reaction at 65°C works best. The temperature can then be adjusted to between 70°C and 85°C. A 4% emulsifier content and a 2.5% initiator dosage also produce the best results. By controlling the reaction pressure, we were able to create VAE emulsions with ethylene contents from 9% to 23%. By replacing part of the protective colloid with hydrophobic-modified PVA, the water resistance of the emulsions was significantly improved.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com